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Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

UNITED STATES

DEPARTMENT OF AGRICULTURE

LIBRARY

Book number

1

Ag»6Cm
no. 81
1927
350601

UNITED STATES DEPARTMENT OF AGRICULTURE

MISCELLANEOUS CIRCULAR No. SI

WASHINGTON, D. C.

ipplement

f oil*

FEBRUARY, 1927

THE RELATIONS BETWEEN CROP YIELDS

AND PRECIPITATION IN THE

GREAT PLAINS AREA

By E. C. CHILCOTT, Senior Agriculturist, in Charge of Office of Dry-Land Agriculture, Bureau of Plant Industry

CONTENTS

library, U, S, Department of Agricultw^
Washington, 0, C,

Page

Introduction 1

Tie crop year 3

Crop yields 4

Methods of presentation of results 5

Comparisons of data presented at the several stations 7

Results at Williston, N. Dak. 9

Results at Assinniboine, Mont 10

Results at Moccasin, Mont 11

Results at Huntley, MonL 18

Results at Dickinson, N. Dak. 19

Results at Mandan, N. Dak. 23

Results at Edgeley, N. Dak. 24

Results at Sheridan, Wyo 26

Results at BeDefourche, S. Dak. 30

Results at Ardmore, S. Dak. 31

Results at Scottsbluff, Nebr 35

Results at North Platte, Nebr. 38

Results at Archer, Wyo 40

Results at Akron, Colo. .".;'"..' 44

Results at Colby, Kans, 45

Results at Hays, Kans. 49

Results at Garden City, Kans. ,,,,,,,,,..,,.... 51

Page

Comparisons of data presented at the several stations — Continued.

Results at Woodward, Okla. 56

Results at Daihart, Tex. 57

Resells at Tucumcari, N. Mex 61

Results at Amarillo, Tex. 64

Results at Lawton, Okla. 66

Results at Big Spring, Tex. . 68

Results at the northern group of 16 stations . 71

Grouping of composite crop yields 71

Average yields of v/heat and oats 76

Results under irrigation at Huntley, Bellefourche, and Scottsbluff . 80

Relations between crop yields and evaporation 83

Relations between crop yields and seasonal precipitation 83

Quantity of wheat produced for each inch of rainfall 84

Summary of precipitation, crop-yield, and ratio data 86

Relations between crop yields and seasonal evaporation as compared

with annual precipitation . . . 86

Reduction of yields due to factors other than deficient annual pre-
cipitation 87

Estimating the magnitude of inhibiting factors 89

Summary and recommendations , , 93

WASHINGTON
GOVERNMENT PRINTING OFFICE

1927

*4i

L

UNITED STATES DEPARTMENT OF AGRICULTURE

MISCELLANEOUS CIRCULAR No. 81

WASHINGTON, D. C.

FEBRUARY, 1927

THE RELATIONS BETWEEN CROP YIELDS AND PRECIPITATION

E. C. CHILCOTT
Senior Agriculturist, in Charge of Office of Dry-Land Agriculture, Bureau of Plant Industry

CONTENTS

Introduction 1

The crop year 3

Crop yields 4

Methods of presentation of results _. 5

Comparisons of data presented at the several stations 7

Results at Williston, N. Dak 9

Results at Assinniboine, Mont 10

Results at Moccasin, Mont 11

Results at Huntley, Mont 18

Results at Dickinson, N. Dak 19

Results at Mandan, N. Dak 23

Results at Edgeley, N. Dak 24

Results at Sheridan, Wyo 26

Results at Bellefourche, S. Dak 30

Results at Ardmore, S. Dak 31

Results at Scottsblufl, Nebr 35

Results at North Platte, Nebr 38

Results at Archer, Wyo 40

Results at Akron, Colo 44

Results at Colby, Kans 45

Results at Hays, Kans 49

Comparisons of data presented at the. several stations — Continued.

Results at Garden City, Kans 51

Results at Woodward, Okla _ _ 56

Results at Dalhart, Tex 57

Results at Tucumcari, N. Mex 61

Results at Amarillo, Tex _ 64

Results at Lawton, Okla ___ 66

Results at Big Spring, Tex 68

Results at the northern group of 16 stations ,_ 71

Grouping of composite crop yields 71

Average yields of wheat and oats 76

Results under irrigation at Huntley, Bellefourche, and Scottsblufl 80

Relations between crop yields and evaporation 83

Relations between crop yields and seasonal precipitation 83

Quantity of wheat produced for each inch of rainfall 84

Summary of precipitation, crop-yield, and ratio data 86

Relations between crop yields and seasonal evaporation as compared with

annual precipitation 86

Reduction of yields due to factors other than deficient annual precipitation . 87

Estimating the magnitude of inhibiting factors. 89

Summary and recommendations 93

INTRODUCTION

""THE RELATIONS between crop yields and precipi-
■ tation probably have been subjects of wonder and
surmise ever since the dawn of civilization. A few
facts and many fallacies have been inherited by the
present generation. The following chronicle of facts
and events bearing upon this subject is arranged so
as to be readily understood by farmers who are inter-
ested in the agricultural possibilities and limitations of
the Great Plains.

The annual crop yields are expressed in figures
representing bushels per acre, and the annual precipita-
tion in figures representing inches of rainfall. It
therefore becomes necessary to use averages, percent-
ages, deviations from the mean, and ratios in order to
show the relations, if any, between the facts presented ;
but beyond this no mathematical formulas or coefficients
are used. Even where such mathematical expressions
are used, they are intended to convey general impres-
sions only. No attempt is made to reach mathematical
exactness in the conclusions as to the relations of these
facts.

No efforts have been made to support or to refute
any theories or preconceptions. We are now in-
terested only in actual facts and their relations. No
single fact or phenomenon has been omitted, minimized,
or exaggerated for the purpose of making some theory
appear more plausible or less so. On the contrary, an
earnest effort has been made to present the facts as
they appeared to the original observers who noted
them in the field. The large number of these observers,
their practical experience, and their intimate knowledge
of the agricultural and meteorological conditions and

11810°— 27 1

problems of the region would seem to assure the reduc-
tion of the personal equation to the minimum.

The purpose will be to give the facts that have been
established by the equivalent of 303 years of practical
experience on 23 farms located at designated points in
the Great Plains area (fig. 1), together with a detailed
report of the climatic conditions that have prevailed
on each of these farms during the entire period of these
investigations.

The detailed descriptions, comments, and explana-
tions given in connection with the reports on yields are
based upon the field notes taken by the respective
associate agronomists who were in charge of the in-
vestigations at each of the 23 stations during the
entire period. The total number of such men who have
had charge of these field investigations during the last
20 years is 66. 1

1 The members of the scientific staff of the Office of Dry-Land Agriculture who have
participated in conducting these investigations in the field and in assembling the
data in the Washington office are as follows: Present staff. — Washington, D. C:
E. C Chilcott, J. M. Stephens, E. F. Chilcott, J. S. Cole. Mandan, N. Dak.,
Robert Wilson, J. T. Sarvis, W. P. Baird, J. C. Thysell, T. K. Killand. Dickinson:
N. Dak.: L. Moomaw. Assinniboine, Mont.: G. W. Morgan. Moccasin, Mont..
A. Osenbrug. Huntley, Mont.: A. E. Seamans. Bellefourche, S. Dak.: O. R.
Mathews. Ardmore, S. Dak.: F. L. Kelso, J. D. Kelso. Sheridan, Wyo.: R. S:
Towle. Archer, Wyo.: A. L. Nelson. North Platte, Nebr.: L. L. Zook, H. E.
Weakly. Akron, Colo.: J. F. Brandon. Colby, Kans.: B. F. Barnes. Hays, Kans..
A. L. Hallsted. Garden City, Kans.: E. H. Coles. Woodward, Okla.: L. F.
Locke. Dalhart, Tex.: H. J. Clemmer. Tucumcari, N. Mex.: D. R. Burnham,
Lawton, Okla.: W. M. Osborn. Big Spring, Tex.: F. E. Keating— 29. Resigned
or transferred to other offices. — Sylvester Balz, F. L. Kennard, J. E. Payne, L. E.
Hazen, C. A. Jensen, H. R. Reed, W. O. Whitcomb, C. H. Plath, F. Knorr, R. W.
Edwards, H. C. McKinstry, C. A. Burmeister, J. G. Lill, W. W. Burr, J. H. Jacobson,
O. J. Grace, M. Pfaender, W. D. Griggs, J. E. Mundell, W. A. Peterson, H. G.
Smith, L. N. Jensen, A. J. Ogaard, C. B. Brown, L. D. Willey, J. B. Kuska,
C. H. Ruzicka, A. W. Schulz, W. E. Lyness, F. A. Wagner, F. E. Cobb, P. V.
Cardon, N. O.Henchel, J. W. McLane, O.A.Thompson, Clarence Harris, and U. G.
Downey— 37. Total, 66.

The field investigations at Assinniboine and Moccasin, Mont.; Williston, Dick-
inson, and Edgeley, N. Dak.; Archer, Wyo.; North Platte, Nebr.; Colby and Hays
Kans.; and Tucumcari, N. Mex., herein described, were conducted cooperatively
at field stations operated by the agricultural experiment stations of the several
States, respectively.

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

It is believed that the investigations which have been
conducted on the Great Plains by the Office of Dry-
Land Agriculture during the last 20 years furnish data
having a direct bearing upon the problems involved in
determining the relations between crop yields and
precipitation such as can not be obtained at Ihe present
time from any other source.

There are certain conditions surrounding the investi-
gation of these problems that have been met in order
to provide a sound basis for safe conclusions, such as

Fig. 1.— Sketch map of the Great Plains area, which includes parts of 10 States and
consists of about 450,000 square miles of territory. Its western boundary is in-
dicated by the 5,000-foot contour. The location of each Held station within the
area is shown by a dot within a circle (O)

heretofore have never been provided; among these
are the following:

(1) The investigations have been conducted in a
semiarid region where there is no permanent water
table near the surface and on land nearly level, but
with sufficient slope for good surface drainage.

(2) The crops have been grown under natural field
conditions, subject to all the hazards to which the
farmer's crop is subject.

(3) The climatic data have been gathered on the
same farm upon which the crops were grown.

(4) The investigations include a sufficient range of
crops, soils, climatic seasons, tillage methods, and crop
sequences to reduce to the minimum the effects of

accidental combinations of factors that might seriously
impair the value of the results obtained.

(5) The varieties and strains of crops used were well
adapted to local conditions of soil and climate.
' (6) Both the crop and the meteorological observa-
tions have been under the immediate personal super-
vision of a trained scientific agronomist who has noted
and recorded at the time and on the spot every fact
and incident that occurred, from the beginning of one
crop year to the beginning of the next, that could
reasonably be expected to influence the crop yield
or in any way modify the effects of climatic or soil
conditions.

(7) All of the data gathered by the scientists in
immediate charge of the field investigations have been
assembled, checked, compared, analyzed, interpreted,
and recorded by experienced investigators, who have
as complete knowledge of the investigations and of the
conditions throughout the entire Great Plains area
as the field investigators have of their respective local
problems and conditions.

Table 1 shows the locations of the 23 field stations
at which the investigations have been conducted,
together with condensed information as to length of
periods and number of plats used at each station.

Table 1. — List of field stations, showing the number of plats used
for planting each crop at each station and the total number of
plats upon which crop yields are based

Field stations

Williston, N. Dak

Assinniboine, Mont

Moccasin, Mont

Huntley, Mont..

Dickinson, NT. Dak

Mandan, N. Dak

Edgeley, N. Dak

Sheridan, Wyo.

Bellefourche, S. Dak_.

Ardmore, S. Dak

ScottshlutT, Xebr

North Platte, Nebr....

Archer, Wyo

Akron, Colo

Colby, Kans

Hays, Kans..

Garden City, Kans...

Woodward, Okla

Dalhart, Tex

Tucumcari, X. Mex. .

Amarillo, Tex

Lawton, Okla

Big Spring, Tex

Number of plats used for crops shown

Crops for grain only

Wheat

23

2
30

12, 39
Hi 27
25 19
13 30

sL

40.

k7 m

28i 28
50|
32

41

20.

Total

Average (round
numbers).-

312 43.'.
21 31

Kafir

63

19
48....

29....

41 ....

23....

60

25

44

27

42

36

22

:•::

27

15

21

17

38

ir.7

•163
•20

•131

20

2"
20

64
168

91
136

80
216

86
154

95
134
111

89
114

1".'
53

62
43

37
86

70

24

12

9

' 17

i 13

18

11

17

8

>17

12

10

< lv

11

16

• 11
IS
16
10
16
12
13
B
•J

768

1,512

1,541

1,743

1.440

2,365

1,462

1,232

1,582

1,608

1.110

1,502

1,254

1,568

1,026

1.S36

848

770

S32

516

481

774

630

;t«; 28, 4ii0

98 13 1,235

i Winter wheat, IT, years.

' Winter wheat, 12 years.

J Corn and winter wheat, 16 years.

I \\ niter wheat, 25 plats for 13 years; barley, 5 plats for 5 years.

I Barley and milo for only Hi yours.

» The same plats of kaflr were used for both grain and total.

It will be noted that the average length of time that
these investigations have been conducted is approx-
imately 13 3Tears, ranging from 8 to IS years and aggre-
gating 303 years. The number of pints used at each
station each year ranged from 37 to 215 and averaged
98 per station. The number of plats used at all stations
each year was 2,252, and the number used at ail
stations for all years was 28,400, which is an average
of 1,235 per station.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

The average numbers of plats used at each station
each year for determining the average yields for each
crop were as follows: Winter wheat, 21; spring wheat,
31; oats, 37; barley, 10; corn, 29; milo, 24; kafir, 20;
cotton, 24. In most cases the plats used at any given
station differ from one another in some way as to
methods of tillage or crop sequence. There are,
however, some exact duplications.

In this connection no consideration will be given to
the effects of tillage or crop sequence. These problems
have been described in various other publications.
Still more are in preparation and are to be published
soon. In fact, the investigations herein recorded are
considered the foundation for an intensive study of
the results of crop rotations and tillage methods. If
the yields from only the plats of highest production
each year had been used, a much better showing would
have been made of the agricultural possibilities of
the region. On the other hand, if the lowest yields
only had been used, the showing, obviously, would
have been much lower. If tbe yields from each plat
had been given, it would have made the problems of
interpretation much more complex, and the conclu-
sions in the end necessarily would have been based
upon average yields from all plats.

It was therefore decided that only average yields
should be used. Another reason for the use of aver-
ages is the fact that the crops grown in the immediate
vicinity of the field stations by the better class of
farmers have produced yields approximating, in a
general way, those represented by our average yields,
rather than by either our maximum or minimum yields.

Table 2 gives the monthly and annual means of
precipitation for each of the 23 stations where these
investigations were conducted.

Table 2. — Monthly and annual average precipitation at 23 field
stations in the Great Plains area

[Arranged in the order of magnitude of the northern crop-year precipitation, stated

in inches]

6

Field stations

3
to

3

<

,0

a

ft

OQ

u

XI
o

O

s

>
o

t-.

a
&

ts

p

>>

cs
3

a
<a

Ha

>>

C3
3

,Q

.a
a

03

ft
<

03

a

3
Ha

3

53

3

a
a
<

i

Lawton

2.08

2.12

5.03

1.43

0.89

1.23

0.62

1.86

3.47

4.12

2.91

2.75

28.51

2

Woodwp.rd

2.87

3.61

2.66

.93

.68

.88

.80

1. 82|2. 75

3.42 3.11

1.84

25.37

3

Hays

3.04

2.01

1.35

.84

.76

.28

.77

.77,2.28

3.36,3.60

2.53

21.59

4

Colby....

2.48

1.86

1.22

.66

1.03

.34

.75

. 85,2. 30

2. 70 2. 56

3.54

20.29

5

North Platte

2.77

1.37

1.26

.66

.73

.38

.65

. 84 1. 91

3.113.15

3.19

20.02

6

Garden City

2.48

1.97

1.20

.75

.67

.33

.92

.881.97 2.482.80

2.56

19.01

7

Amarillo-- __.

3.05

2.25

1.47

.90

.81

.18

.73

.47

1.69

2. 492. 01

2.71

18.76

8

Tucumeari ___

2.72

1.78

1.87

.54

.76

.40

.35

.82

2.04

2. 77 2. 64

2.02

18.71

9

Dalhart

2.51

1.34

1.68

.54

.57

.25

.40

.81

2.04

3. 12 3. 19

2.23

18. 68

10

Akron

2.14

1.58

1.13

.62

.82

.39

.55

.87

2.41

2. 72 2. 08

2.50

17.81

11

Big Spring

2.08

1.59

2.17

.82

.45

.50

.61

1.19

2.57

2. 18 2. 67

.97

17.80

12

Moccasin

1.68

1.66

1.25

.70

.74

.73

.62

.85

1.28

2. 69 3. 21

1.70

17.11

13

Edgeley. -

1.96

1.94! .85

.38

.30

.27

.30

.501.72

2.93

3.17

2.69

17.01

14

Ardmore

1.33

1.24:1.08

.45

.45

.31

.42

. 57 2. 28

3.25

3.10

2.21

16.69

15

Dickinson

2.01

1.371 .87

.48

.37

.37

.39

. 64 1. 21

2.28

3.49

2.57

16. 05

16

Mandan

1.18

1. 53 1 .75

.52

.43

.21

.34

. 79 1. 56

2.31

3.38

2.88

15.88

17

Bellefourche

1.46

1.601.10

.48

.53

.46

.43

.67

1.50

2.60

2.47

2.50

15.80

18

Seottsbluff

1.87

1.94 .90

.20

.47

.22

.33

.70

2.06

3.06

1.71

1.60

15. 06

19

Archer

2.16

1.3211.09

.59

.61

.21

.43

.54

2.12

2.21

1.81

1.72

14.81

20

Sheridan..

.61

1.841.33

.68

.45

.69

.32

.88

1.80

2.39

2.29

1.51

14.79

21

Huntley

.89

1.57

1.21

.84

.81

.65

.38

.87

1.20

2.22

2.60

1.52

14.76

22

Williston.

2.18

1.23

.86

.56

.54

.53

.33

.71

1.08

1.97

2.89

1.80

14.68

23

Assinniboine

Mean

.97

1.51

.60

.28

.50

.64

.36

.51

.87

1.52

2.80

1.80

12.36

2.02

1.75

1.43

.65 .62

.45

.51

.84

1.92

2.69

2.77

2.23

17.89

These stations are here arranged in the order of the
magnitude of the annual precipitation for the northern
crop year, from August to July, inclusive. No dis-
tinction is made in this table between the stations
which, in some of the tables which follow, are divided
into northern and southern crop-year groups. The

figures here given show the actual precipitation occur-
ring each month for the northern crop year, whereas in
some of the tables following the cumulative precipita-
tion is shown.

THE CROP YEAR

For the purpose of this presentation it has seemed
desirable to establish two different crop years, one for
the North and one for the South. For the northern
group of stations, 16 in number, the crop year begins
August 1 and ends July 31 of the following calendar
year. For the southern stations the crop year begins
October 1 and ends September 30 of the following
calendar year. The reasons for the selection of these
periods for the crop years are that it is desirable to
have the year begin as nearly as possible at the time
when the principal crops mature and before the be-
ginning of the preparation of the soil for the next crop.
At the northern stations where spring wheat, winter
wheat, and oats are the most important crops, this
date is about August 1. At the southern stations,
where the growing season is longer, October 1 is a better
date, as many of the crops grown there do not mature
until about that date.

By the adoption of crop years, as indicated, all the
rain that falls after the harvesting of one crop is
charged to the next crop, and tillage methods calcu-
lated to conserve the moisture can be adopted.

There are some exceptions to this general rule — as,
for example, the corn crop in the northern Great Plains
area does not mature until September, thus utilizing
the rainfall of August and a portion of September of
the following crop year. Winter wheat and early-sown
spring crops on the southern Great Plains mature
before the end of the crop year for that locality, therebj^
making it possible to begin moisture conservation
operations during the latter part of one crop year for
the benefit of the next year's crop. All of these facts
are taken into consideration in adopting cropping sys-
tems and in estimating the relations between crop yields
and precipitation.

Nevertheless, most of the staple crops grown through-
out the Great Plains can be studied more satisfactorily
by using the crop years, as indicated, respectively, for
the northern and the southern portions, instead of the
calendar year.

In Table 3 the same monthly and annual precipita-
tions are used as in Table 2, but they are presented
cumulatively.

The term "cumulative precipitation" is used in these
pages to designate the total precipitation that has
occurred in the interval between the beginning of the
crop year and the close of each month during the crop
year. The cumulative precipitation for the first month
of the crop year is, of course, the precipitation for that
month; for the second month it is the sum of the pre-
cipitation for the first and second months; for the third
month it is the sum of the first, second, and third —
and so on to the end of the year. The cumulative
precipitation for the last month of the crop year is the
same as the total precipitation for the crop year.

The stations are arranged in two groups, the south-
ern and the northern. Within the respective groups
the stations are arranged in the order of magnitude of
the precipitation for the crop year; and the average
annual yields for four of the leading crops for the
respective localities are given on the same line follow-
ing the precipitation.

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Table 3. — Average cumulative monthly precipitation and comparative crop yields at 23 field stations in the Great Plains area

[Arranged in order of magnitude of yearly precipitation for two groups of crop years: Southern group, October to September, inclusive; northern group, August to July

inclusive. Yields of four leading crops arranged in same order]

Cumulative precipitation (inches)

Averag

e acre yields

Field stations

Wheat

Oats

Bar-
ley

Corn

orghum

Cot-
ton,
lint

Milo
grain

Kafir

Years

aver-

Win-
ter

Spring

aged

Oct.

Nov.

Dec.

Jan.

Feb.

M IT

Apr.

May

June

July

Aug.

Sept.

Grain Total

Grain Total

Southern group:
Lawton

5.03
2.66
1.20
L47
1.87
L68
2.17

6.46
3.59
1.95
2.37
2.41
222
2.99

7.35
4.27
2.62
3.18
3.17
2.79
3.44

8.58
5.15
2.95
3.36
3.57
3.04
3.94

9.20
5.95
3.87
4.09
3.92
3.44
4.55

11.06
7- 77
4.75
4.56
4.74
4.25
5.74

14.53
10.52
6.72
&25
6.78
6.29
8.31

18.65
13.94
9.20
8.74
9.55
9.41
10.49

21.56
17.05
1200
10.75
12.19
12.60
13.16

24.31
18.89

26.39
21. 76

28.51
25.37
19.01
18.76
18.71
18.68
17.80

Bus.
16.6
16.6

Bus.

Bus.

Bus.

Bus.

Lbs.

Bus.

Bus. Lbs.
16 0 4 002

Lbs.
9nn

q

Woodward

19.2
18.1
23.2
25.7
23.1
22.2

20.8 5, 140

10

Garden City

14.56 17.04

7.9

16

Amarilln

13.46
14.21
14.83
14.13

16.51
16.93
17.34
16.21

7.3

13. 2 4, 819
18.7 3,668
19. 1 ] 5,819
15. 6 3 569

206

13

12

Tuoumeari. .

16.6
13.4

Dalhart

16

Big Spring

9

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

18.2
19.2
18.8
12 2

17.1

14.9

15.1
10.6
10.8
21.8
23.0

8.6

19.9
22.6
21.5

6.1
20.9
19.8
13.8

2,883
3,308
3,779
2,612
4,578
3,825
2,991
3,509
4,264
3.479
3,301
2,822
2,979
3,313
4.2*2
2,763

""io.~5

19.0

Northern group:
Hays

3.04
2.48
2.77
2.14
1.68
1.96
1.33
2.01
1.18
L46
1.87
2.16
.61
.89
2.18
.97

5.05
4.34
4.14
3.72
3.34
3.90
2.57
3.38
2.71
3.06
3.81
3.48
2.45
246
3.41
248

6.40
5.56
5.40
4.85
4.59
4.75
3.65
4.25
3.46
4.16
4.71
4.57
3.78
3.67
4.27
3.08

7.24

6.22
6.06
5.47
5.29
5.13
4.10
4.73
3.98
4.64
4.91
5.16
4.46
4.51
4.83
3.36

8.00
7.25
6.79
6.29
6.03
5.43
4.55
5.10
4.41
5.17
5.38
5.77
4.91
5.32
5.37
3.86

8.28
7.59
7.17
6.68
6.76
5.70
4.86
5.47
4.62
5.63
5.60
5.98
5.60
5.97
5.90
4.50

9.05
8.34
7.82
7.23
7.38
6.00
5.28
5.86
4. 96
6.06
5.93
6.41
5.92
6.35
6.23
4.86

9.82
9.19
8.66
8.10
8.23
6.50
5.85
6.50
5.75
6.73
6.63
6.95
6.80
7.22
6.94
5.37

12.10
11.49
10.57
10.51
9.51
8.22
8.13
7.71
7.31
8.23
8.69
9.07
8.60
8.42
8.02
6.24

15.46
14.19
13.68
13.23
12 20
11.11
11.38
9.99
9.62
10.83
11.75
11.28
10.99
10.64
9.99
7.76

19.06
16.75
16.83
15.31
15.41
14.32
14.48
13.48
13.00
13.30
13.46
13.09
13.28
13.24
12.88
10.56

21.59
20.29
20.02
17.81
17.11
17.01
16.69
16.05
15.88
15.80
15.06
14.81
14.79
14.76
14.68
12.36

18

Colby

11

North Platte

12.9
9.7
17.6
16.9
17.4
19.3
17.1
16.9
11.8
10.8
17.0
16.4
16.1
13.6

28.3
2L3
36.1
34,6
32.8
39.5
40.3
35.5
24.1
17.0
36.5
34.9
35.0
26.0

18

Akron

16

Moccasin

17

Edgeley

20.5

24.6
21.8

21.0

15.0
15.1
29.0
21.1
20.7
15.9
18.6
20.6

17

Ardmore

12

Dickinson

18

Afandan

11

Bellefourche

17

ScottsblufL

10

Archer

11

Sheridan

8

Huntley .

13

Willis ton

12

Assinnihninp

9

Average

17.89

15.4

15.3

31.6

21.7

17.0

3,418

21.1

16.9 4,398

203

The figures from which these summaries are derived |
are given in detail under "Comparisons of data pre- 1
sented at the several stations."

CROP YIELDS

It will be noted that "Kafir total" is given in pounds
per acre as one of the leading crops grown at all of the
southern stations and that "Corn total" is given for
all of the northern stations. These crops are grown for
silage, and the entire crop, both grain and stalks, is
used. If sold for market prices on the farm, these crops
would not prove profitable; but, as they fit into the
rotations and provide feed for livestock, they have a
value in the farming system far exceeding their market
value if sold in the raw state. At most of the northern
stations the yields of grain from the corn crop are
sufficient to afford a standard of values for the crop in
the general farming system. In such instances both
the yields of shelled corn and the total weight of the
crop are given.

Table 4. — Average yields of wheal, oats, barley, corn, and sorghum
in the Great Plains area, compared with those of other regions,
from 1908 to 1920, inclusive

Average acre yields of grain (bushels)

Region covered

Wheat

Oats

Barley

Corn

Sorghum

Spring
wheat

Win-
ter

wheat

Mil..

Kafir Total

12 8
It :i

15.6

l.V 1

31.6

::i <.

L'l 7

26.5
17.11

21.1

16 Q 19.0

25

-.2

-3. 2 -9. 5

-L4

The Agricultural Yearbook, 1923 (pp. 605-606, 665,
682, 698, 729), gives the average yields of wheat, corn, •
oats, barley, and sorghum in the United States for the
periods from 1908 to 1920, inclusive. In Table 4 these
yields are compared with the yields of these crops in
the Great Plains area.

From Table 4 it appears that the average yields of
winter wheat as determined by these investigations
were substantially the same as the Yearbook figures:
For spring wheat, 2.5 bushels higher; for oats, the
same; for barley, 3.2 bushels lower; for the gin in sor-
ghums (milo and kafir averaged 19 bushels), 1.4 bushels
lower. The yields of corn have been relatively low,
in fact only about two-thirds that of the United States
as a whole. This is as would be expected, as no part
of the Great Plains as represented by these investiga-
tions can be considered a corn country. Corn, however,
is a profitable crop to grow to a certain extent in much
of the northern portion of the area, as heretofore
explained.

In this connection it must be borne in mind that the
crop yields herein reported are the average yields
obtained from a number of different methods of tillage
and crop rotation, some of which are known to be
inefficient, but which are used for the purpose of com-
parison with other more efficient methods. These
investigations show that no one method always gives
the best results at any individual station, the varia-
tions in climatic conditions from year to year making
sometimes one and sometime- another the best "1
several different methods or rotations for that par-
ticular combination of soil and climatic conditions and
crop requirements. Such being tin1 case, it is practi-
cally impossible to make any definite mathematical
calculation of just what average yields would have been
obtained if only the best methods and rotations hail
been used each year at each station upon all the plats.

CEOP YIELDS AND PRECIPITATION IN THE GEEAT PLAINS AREA

The agricultural hazards on the Great Plains are of
a somewhat different character from those of more
humid regions. At each one of the 23 stations there
have been years when crop failure was practically com-
plete. In some instances such years have occurred in
unbroken succession for two or more years. Some-
times these failures have been due to insumcient annual
precipitation, sometimes to hail, and sometimes to a
combination of both. Inopportune distribution of pre-
cipitation is frequently the cause of serious crop losses.
Plant diseases, insect pests, and weeds may also become
important factors, although they are not usually as
serious hazards here as in more humid regions. Soil
blowing is an ever-present menace during the spring
months. This danger is not confined to light, sandy
soils as is sometimes assumed. In some instances it
occurs with disastrous effects upon heavy clay soils,
where the clay will be torn off in flakes from the sur-
face of the soil and be carried along by the wind with
the same results as those of sand particles on sandy soils.

Heavy winds occurring when the small-grain crops
have reached or are approaching maturity some-
times do great damage by shattering the heads and
breaking down the stems. Along the international
boundary in North Dakota and Montana, and across
the line in Canada, frost damage may occur, both in
the spring and just before maturity of the crops in late
August or in September. In Texas, Oklahoma, and
New Mexico heavy rains sometimes occur in September,
October, and November that make the curing of late-
maturing crops of sorghums difficult and may result
in serious loss to the crop after it has been grown and
harvested. All these conditions and many others,
some known and others unknown, may be included
under the general term "inhibiting factors." This
term will occur frequently in these pages and is always
used to include all factors other than insufficient an-
nual precipitation which tend to reduce crop yields
below those that have been obtained at the same sta-
tion in other years with no greater annual precipita-
tion.

This is a rather formidable array of hazards to which
crops in semiarid regions are subject, but it is probably
no worse than those to which crops in humid regions
are subject and possibly not so bad as they are. Never-
theless, the inhibiting factors must be recognized, for
some of them undoubtedly are sufficiently potent
in the growth of every crop to prevent the production
of the yields that should be produced when the annual
precipitation is normal or above.

It is customary to think of the number of inches
of annual precipitation as the most important factor
in determining the success or failure of crop produc-
tion on the Great Plains. The fertility of the soil may
be considered as a constant, as practically all soils
in this region are sufficiently- fertile to produce abun-
dant crops if the climatic conditions are favorable.

These investigations seem to indicate that not only
the seasonal and monthly but also the daily distribu-
tion of the precipitation may be much more important
than its annual magnitude. They also raise the ques-
tion as to whether the inhibiting factors already men-
tioned may not be of greater importance than either
annual precipitation or soil fertility. This matter
is given careful consideration in the text accompanying
the diagrams.

Having enumerated in some detail the hazards of
agriculture on the Great Plains, it is only fair to call
attention to some of its advantages. Among these

are the following: Land is relatively cheap. It is
much more easily tilled than that of most of the humid
regions. These two conditions combine to make pos-
sible a more extensive and a more economical system
of crop production than can be conducted where land
is high priced and relatively difficult to till. The
climate of the entire Plains region is healthful and in-
vigorating. The population, as a rule, is progressive
and enterprising. School and cooperative social and
business organizations thrive in the agricultural com-
munities. Good roads and automobiles, the telephone,
and the radio have practically eliminated the isolation
of the farm home, which was so serious a menace to the
happiness and culture of the early settlers in that
region.

METHODS OF PRESENTATION OF RESULTS

As far as possible, the diagrams and tables which
follow are self-explanatory, but attention is here called
to the following features of this method of presentation.
Diagrams showing in detail the relations between
annual crop yields and precipitation by five-day,
monthly, and crop-year periods are given for each of
the 23 field stations, each detailed presentation being
summarized graphically by a facing diagram in each
instance. The presentations thus shown as a series in
pairs are referred to as Figures 2 to 47, inclusive.

For the first 16 stations, representing the northern
group, the crop year begins August 1 and continues to
July 31 of the following calendar year. For the 7
southern stations the crop year begins on October 1 and
ends September 30 of the following calendar year. The
reasons for the selection of these periods have been
explained under "The crop year." The precipitation
is given in inches diagrammatically for each five-day
period and in figures by months. The total precipita-
tion for the crop year is given in inches in the first
column at the right of the July and September columns,
respectively, in the detailed presentations. The sea-
sonal precipitation for the four growing months,
April to July, inclusive, is given in Table 14 (p. 84) and
is included in the graphic summary for each station.
In the even-numbered figures of this series the two
columns to the right of the one occupied by the figures
for the annual precipitation for the crop years contain
the names of the crops studied at each station and their
respective yields per acre expressed in bushels or pounds
per acre for the respective crops. The extreme right-
hand column indicates the year when the crops were
harvested, or the crop year. The figures in the extreme
left-hand column indicate the calendar year of the fall
and winter months included in the crop year. The
two horizontal lines at the bottom of these even-num-
bered figures show, respectively, the name of the months
and the average monthly precipitation for each month
and the average annual precipitation for the period of
years covered by these investigations at that station.

The odd-numbered figures of the series are so ar-
ranged that the upper portion of each is devoted pri-
marily to crop yields and incidentally also to seasonal
rainfall and evaporation, while the lower portion is
devoted entirely to precipitation. The value assigned
to each fine horizontal line is expressed on the scale at
the left-hand side of each figure, indicating either
inches or bushels, as the case may be. The perpendic-
ular lines indicate crop years. The years are not ar-
ranged in chronological sequence, but in the order of
magnitude of the annual precipitation for each year,

MISCELLANEOUS CIRCULAR 81, TJ. S. DEPARTMENT OF AGRICULTURE

WILLISTON CN. DAK.> FIELD STATION

YEAR

r

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1908

4

I . II

2. IB

1 81

.16

.01

.31

.10

12

.64

2 84 | 3.72

1 72

1472

BARLEY
S.WHEAT

43.4

~ 27.5

1909

3

J

2

1

OATS

65.3

■

I

Ljl—

nJ

a. .

_ l> J-l

"»=»^

CORN #

6718 0

1909

4

'.38

1.27

.17

.20

.46

.27

.34

1.31

1.40

1 30

1 65

1 27

1002

BARLEY

1.4

1910

S

S.WHEAT

1.8

2

OATS

3.5

1

, _

_,_ L

,

., ,., _

J ■ ■

^Jt^i

■htz^b im.,.mr.

CORN **■

1791 0

1910

4

1.69

.1+

OS

.66

.28

.S6

.34

.20

.32

3.00

1 .37

1 .40

1 0.01

BARLEY

6.1

1911

3

S.WHEAT

4 6

2

OATS

1 1.0

1

~ —

iUL

CORN #

3574.0

1911

4

2.56

2.49

.53

1.25

59

.44

.17

.35

2.13

4.59

1 .59

3.60

2C 2?

BARLEY

42.6

1912

3

S.WHEAT

370

2

OATS

63.2

■ 1 _l ■

1

=-— - M "

B

Hfcrrr

— -

CORN *

(a)

1912

4

3.4-7

1.21

1.12

.14

.18

.52

.14

.94

27

1.05

2.15

2.60

13 79

BARLEY
S.WHEAT

19.1
15.2

1913

3

2

■

OATS

37.8

■

•1

_ZZfc^t

— ITT

,, mXU,

CORN #

f)

1913

4

5.50b

1.13

.89

.15

T

.55

.28

.50

.49

1 .21

7.98

2.32

2 1 CO

BARLEY

36.7

1914

3

■

N

S.WHEAT

25.7

■

■

2

- ■

■ J

OATS

71.0

■ B

■ ■■ H ■

1

H a

■ ■MB

COSN #

7639.0

1 1

D , ..■

i^i ' ■

.,.!_, 1-1

■ 1 !■■

. .... __■.

1914

4

3.55

.64

.38

.24

.33

.38

.18

.13

.71

2.08

2.02

2.42

13 06

BARLEY

27.9

1915

3

S.WHEAT

24.1

2

■

OATS

46.1

■

1

■— I"

_J_Jfc

CORN #

24 1 9.0

1915

4

.41

1.74

1.76

2.08

.88

1.17

.39

.80

1.34

1.88

4.81

1.16

18 44

BARLEY

405

1916

3

S.WHEAT

' 27.7

2

■

OATS

70.8

■

1

m ■

■

■

CORN -#

7268.0

■ ,. -

^m_u^Jt

.i.i i ■

, ,.0.,.

.. .^^JJIH

1916

4

2.45

1.72

.63

.35

1.50

.47

.67

.47

1.26

.08

2.53

.34

12 47

BARLEY

12.2

1917

3

S.WHEAT
OATS

10.3
17.1

a

■

1

J=

■,,,.. 1

-™ «J

.,.. ,.H

-z-aJfc

kJL

CORN 4t

2919.0

1917

4

.24

.90

1 00

.01

1.00

75

.13

.48

2.39

1 .39

.72

2.48

II 49

BARLEY

3.5

1918

3

S.WHEAT

4.2

2

OATS

6.4

1

=m . ,

t ^

,,,,.,

mm

—=.

, lm^_:

—

CORN #

5807.0

1918

4

4.20

.30

.38

1.04

1.00

.07

1.02

1.08

1.12

2.16

2.64

1.33

16.34

BARLEY

4.1

1919

3

S.WHEAT

4.0

2

■

OATS

6.0

■

1

_ , _

■

■

-Jt^J

■ ■.. ,

bi 9

^i-.

CORN #

2778.0

1919

4

.65

.99

I.6S

.46

.25

.92

.13

2. 18

.86

2.03

3.50

.96

1458

BARLEY

14.5

1920

3

S.WHEAT

10.9

2

OATS

22.1

'

-M^rr.

^— -

ttU '

CORN #

1910.0

AVERA

3E

2.18

1.23

.86

.56

.54

.53

.33

.71

1.08

1.97

2.89

1.80

14.68

la) Heavy fodder yield, but
weights not reliable

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

1 1
•?* Corn fodder in pounds

1 T

Fio. 2. — Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Williston (N. Dak.) Field Station

the wettest year at the left and the driest year at the
right. Such an arrangement facilitates comparisons of
the yields of crops grown during years having but
slight differences in annual precipitations, which are
arranged on adjacent perpendicular lines. It also per-
mits the annual precipitation to be represented on a
progressively descending lino from left to right instead
of on a broken line as would be the case if the years
were arranged in chronological order. This regularly
descending line is used as a datum line, or basis of com-
parison, with broken lines representing other factors,
such as crop yields and monthly precipitation. The
values of all precipitation and evaporation data, and of
all crop yields, except those of oats, are read directly
from the scale at the left of the figure. In the case of
oats the yields shown on this scale should be doubled.
This arrangement permits of a much more compact
diagram and facilitates comparisons between oat and
other grain yields. With this single exception, the

upper portion of each figure treats values in conven-
tional form.

The arrangement of the lower portion of the odd-
numbered figures, dealing with precipitation, is easily
understood. The first line above the base represents
the cumulative precipitation of the fall group of
months — August, September, October, and November.
The second line represents the cumulative precipitation
of the months of August to March, inclusive, and the
width of the interval between it and the first line repre-
sents the cumulative precipitation of the winter months

December, January, February, and March. The
third line represents the cumulative precipitation of the
months August to April, inclusive, and the interval
between it and the second line represents the April
rainfall. The other three lines represent the cumula-
tive precipitation from August 1 to May 31, dune 30,
and July 31, respectively. The intervals between

them represent the monthly precipitation of each

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

( Wrllis+on, N. Oak.)

1914 '12 '16 '19 '09 '20 '13 '15 *J7 '18 '!0 Ml

Fig. 3. — Diagram summarizing the relations between rainfall and crop yields at Williston, N. Dak. (See text, p. 9)

month, respectively. The upper line also represents
the cumulative annual precipitation for the crop year.

The lines representing seasonal precipitation and
evaporation are placed in the upper portion of the fig-
ure. It is thus made easy to note at a glance the rela-
tions between crop yields, annual precipitation, sea-
sonal precipitation, and evaporation for any and all
years, the years shown at the bottom being applicable
to both the upper and lower portions of the figure.

Corn is an important crop on the northern Great
Plains, when grown in rotation with wheat and oats.
Yields of either the grain or the total weight of the
corn crop, therefore, are given in the even-numbered
diagrams, but they have been omitted from the odd-
numbered diagrams. The reason for this omission is
that corn is not so well adapted to these climatic con-
ditions as are wheat and oats and is, therefore, of
relatively little value for determining the relations
between crop yields and annual precipitation, for
which purpose the odd-numbered diagrams are espe-
cially designed.

COMPARISONS OF DATA PRESENTED AT THE SEVERAL
STATIONS

In connection with the presentation for each of the
23 field stations are given, for the period covered by
these investigations, the means of the meteorological
factors and of crop yields, the number of plats devoted
to each crop, and the character of the soil at the station
under consideration.

Each crop year is then considered in normal chrono-
logical order. Percentage deviations above or below

means of annual precipitation, seasonal precipitation,
and yields of each of the four crops are expressed in
figures.

To facilitate comparisons of these factors they are
expressed diagrammatically, the perpendicular line
representing the respective means and the horizontal
lines the deviations from the means in percentages of
the respective means. Deviations from the means are
represented by extensions, to the right for those above
the mean and to the left for those below. The relative
lengths of these extensions are proportional to the per-
centages of deviation. If directly proportional rela-
tions existed between the crop yields and the precipita-
tions here represented, these extensions, if any, would
be all in the same direction and to the same extent for
any one year at any one station. That no such pro-
portional relations exist between either seasonal or
annual precipitation and crop yields is obvious from
an examination of these diagrams. Still more con-
clusive are the facts that the mean percentage devia-
tions for all of the 23 stations for the periods during
which these investigations have been conducted, an
aggregate of 303 years, are as follows :

Seasonal precipitation, from 69 above to 49 below,
a range of 118 per cent; annual precipitation from 49
above to 38 below, a range of 87 per cent. For crop
yields the deviations are from 171 above to 99 below,
a range of 270 per cent, which is more than twice as
great for crop yields as for seasonal precipitation and
about three times as great as for annual precipitation.

It is a perfectly obvious fact that crop plants, like
animals, must have water for life and growth. It is
equally obvious that there must be a lower limit to the

8

MISCELLANEOUS CIRCULAR 81, TJ. S. DEPARTMENT OF AGRICULTURE
ASSINNIBOINE (MONT.) FIELD STATION

YEAR

X

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1915

4

.9 4

2.05

.42

.12

.77

1.75

.47

.59

.69

2.6 9

4.32

5.20

20.01

W.WHEAT
S.WHEAT

38.6
49.1

1916

3

2

OATS

92.2

1

■ . <m.. HHHT

M., , , ,

• — ■■

CORN #

4437.0

1916

4

.20

1.90

.82

.15

.58

.51

.20

.04

.86

.42

t 59

.43

7.70

W.WHEAT

7.2

1917

3

S.WHEAT

6.4

2

OATS

10.4

1

H

m^g-

— -■ • ■ -

CORN n

10400

■ . . . i

M i

■L

.. _-■

i -%-t %M

»917

4

.70

5.33

.38

.08

1.32

.75

.25

.40

.44

.08

1.51

.74

11.98

W.WHEAT

6.1

1918

3

S.WHEAT

8.3

9 H

2

■ R

OATS

10.5

1 B

1

1 9

■

CORN tt

2017.0

rr« I . ■■

.■ ■

- —m.

-._._■

!..-_-■

1. 1 - ■

n .

i ib ^

i

■ 1

.. am ™—

1918

4

2.1 0

.64

1.1 7

.42

.05

.38

.56

.50

.31

1.09

1.99

.19

9.40

W.WHEAT

3.7

1919

3

S.WHEAT

3.2

2

OATS

2.6

1

— —

CORN X

452.0

1919

4

.60

.67

.48

.56

.23

.88

.30

.40

1.71

1.39

2.20

1.36

10.78

W.WHEAT

4.6,

1920

3

S.WHEAT

10.8^

2

OATS

22.8

1

■L.

■

m__ .

CORN #

3198.0

1920

4

1.26

.35

1.04

.01

.30

.05

.06

1.81

.80

2.83

2.68

2.16

13.35

W.WHEAT

7.2

1921

3

S.WHEAT

10.1

2

■

OATS

23.7

■

1

fc_. , w

_» M.

JL-Bfc

CORN #

2853.0

1921

4

.53

1.4-5

.1 9

.70

.1 1

.1 9

.76

.27

1.43

2.37

.£0

1.90

10.80

W.WHEAT

6.0

1922

3

S.WHEAT

4.7

2

OATS

11.0

■

1

H_ |

_

— , B-«

-§=rr

CORN #

2697.0

1922

4

.92

.54

.1 1

.31

.56

1.00

.1 5

.05

.78

1.93

4.8 S

3.65

14.86

W.WHEAT

0.0

1923

3

S.WHEAT

18.2

2

OATS

28.8

1

| — t-|_

~TTTT7T

—

B , , ,.

"31

i — _^ B HU^h^A

CORN ft

4486.0

1923

4

1.49

.64

.73

.15

.60

.27

.49

.55

.82

.89

5.14

.61

i 2.38

W.WHEAT

4.1

1924

3

S.WHEAT

11.2

2

OATS

32.1

1

. m _

■

-=

— — =

■ , ■ ,

CORN #

3681 0

AVERAGE

.97

1.51

.60

.28

.50

.64

.36

.51

.87

1.52

2.80

1.80

12.36

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

# Corn fodder in po
1

urtds
1

Fig. 4. — Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Assinniboiiie (Mont.) Field Station

water supply, below which neither plants nor animals
can live, but this limit will vary widely between dif-
ferent plants and animals. It will also be subject to
great variation due to environmental conditions, the
presence of assimilable food, and man}7 other factors.

Assuming that either a crop plant or an animal has
available a sufficient supply of water to continue to
exist and that this supply is gradually augmented above
this minimum, then growth or energy may be devel-
oped, provided other environmental influences are
sufficiently favorable. It is probable that with some
plants and some animals, under favorable environ-
mental conditions, there would come a stage in the
gradual augmentation of the water supply when there
would be a directly proportional relation between
water supply and growth, or the development of energy;
but, if so, it would be through a very narrowly limited
range of increase in the water supply, and even within
this narrow range it is probable that under all ordinary
environmental conditions there would be Inhibiting
factors that would throw these proportional relations
out of equilibrium.

The purpose of introducing the above fuels to the
reader n Lhi point is to enable him correctly to inter-
pret the facts that are herein presented concerning the
relations between precipitation and crop yields; For, if
he has the patience to study carefully these notes,
comments, and comparisons of data covering 303
crop years, he will find hi^ center of interest gradually

shifting away from the rainfall data and centering upon
considerations of the inhibiting factors other than
deficient annual rainfall, which seem to be the major
factors determining the crop yields.

When this stage is reached, the reader will find it
easy to account for the very low yields sometimes ob-
tained when rainfall seems to have been adequate for
the production of a good crop by assuming that there
was some inhibiting factor which was responsible for
the decrease. But when, on the other hand, he finds
very high yields reported when the rainfall is little if
any above the mean, he may at first find difficulty in
explaining the seemingly anomalous circumstance. He
should, however, call to mind the fact that every
inhibiting factor that has influenced the yield of any
crop during the entire period of the investigation of
thai crop at that station has tended to lower the
mean yield of that crop at that station. Therefore,
when a year occurs when there arc comparatively few
inhibiting factors, or their potency is reduced, the
yields may be two or three times the mean, as hap-
pened at Bellefourche and other stations in 1915. It
is thus seen thai inhibiting factors, by their relative
impotence, may explain abnormally high yields. This
subject is considered more fully elsewhere (p. 87).

It is probable that the notes of the field men, par-
ticularly in the earlier years, did not place sufficient
emphasis upon inhibiting factor-, as their real sig-
nificance has dawned but slowly upon investigators.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

( Assinnlbolne, Mont. )

24

21

18

15

12

9

6

3

0

- June ■

Julu ■■■■

May-

Apr.-
.Mar.±

— Nov..

PRECIPITATION

- — ^**^f*" — "TX-JAN-- FEB. - MA R. I^.<*

*" — • ~ ' "~ ■" I aii

AUG. - SEPT. -OCT.- NOV.

ANNUAL MEAN

tt CROP YEAR
GROWING SEASON
WINTER
FALL

1916 '23 '21 '24 '18 '22 '20 '19 '17

Fig. 5.— Diagram summarizing the relations between rainfall and crop yields at Assinniboine, Mont. (See text, p. 10)

RESULTS AT WHXISTON, N. DAK.

[Altitude, 1,875 feet; 12-year period (figs. 2 and 3)]

Climatic conditions: Mean annual precipitation, 14.68 inches;
mean seasonal precipitation, 7.74 inches; mean seasonal evapo-
ration, 33.103 inches.

Average frost-free period, 135 days.

Soil: Sandy loam, largely wind-blown loess.

Number of crop yields averaged each year: Barley, 5; spring
wheat, 19; oats, 21; corn, 19.

Average annual crop yields per acre: Barley, 21 bushels;
spring wheat, 16.1 bushels; oats, 35 bushels; corn, 4,282 pounds.

Crop year 1909
Precipitation :

Annual, mean.

Seasonal, 15 per cent above

Crop yields:

Barley, 107 per cent above

Spring wheat, 71 per cent above.

Oats, 87 per cent above

Corn, 57 per cent above

Almost an ideal crop year. Although the annual precipitation
was about normal, the seasonal precipitation was above the mean
and well distributed. The barley crop was the best ever pro-
duced at the station; wheat, corn, and oats, the third largest.
Frost-free period, 148 days.

Crop year 1910
Precipitation :

Annual, 32 per cent below

Seasonal, 27 per cent below

Crop yields:

Barley, 93 per cent below

Spring wheat, 89 per cent below. _.

Oats, 90 per cent below

Corn, 58 per cent below.

A dry year with a practical failure of all crops except corn,
which made a good growth of stalks, but formed no ears except

on fallow, and these did not mature. The corn was benefited by
the August precipitation of the following crop year. The
precipitation for all months except March and April of the crop
year was below normal. Evaporation was 15 per cent above
normal. Frost-free period, 114 days.

Crop year 1911

Precipitation :

Annual, 32 per cent below

Seasonal, 21 per cent below

Crop yields:

Barley, 71 per cent below

Spring wheat, 71 per cent below

Oats, 69 per cent below

Corn, 17 per cent below

Another dry year, the precipitation for both the crop year and
the season being much below normal. The fact that crops did
not fail as completely as in 1910 was attributed to the lack of hot
days and hot winds which characterized that year. Corn and
flax were considerably damaged by hail after small grains were
in the shock. Corn was frosted August 21 and 22 before any
ears matured. Frost-free period, 171 days.

Crop year 1912

Precipitation :

Annual, 38 per cent above

Seasonal, 53 per cent above

Crop yields:

Barley, 103 per cent above

Spring wheat, 130 per cent above- _

Oats, 81 per cent above

Corn (no data).

The only period of deficient precipitation was the last half of
June, but crops were only beginning to show the effects of drought
when rain came. Corn made a rank growth of stalks and formed
large ears, but it was frosted September 16 before any of them
matured. Frost-free period, 173 days.

10

MISCELLANEOUS CIBCULAR 81, U. S. DEPARTMENT CF AGRICULTURE

Crop year 1913
Precipitation:

Annual, 6 per cent below

Seasonal, 22 per cent below

Crop yields:

Barley, 9 per cent below

Spring wheat, 6 per cent below

Oats, 8 per cent above

Corn (no data).

The fall of 1912 was abnormally wet, and the spring of 1913
opened with excellent prospects. Continued drought until
June 27 depleted the soil water, and the small grain suffered.
Drought again from the middle of July until harvest forced
maturity. August rains provided optimum conditions for corn,
which fully matured before the first killing frost, late in Septem-
ber. Frost-free period, 124 days.

Crop year 19 H.
Precipitation :

Annual, 43 per cent above

Seasonal, 55 per cent above

Crop yields:

Barley, 75 per cent above

Spring wheat, 60 per cent above

Oats, 103 per cent above

Corn, 78 per cent above ■-

The water stored in the soil from rains which came after har-
vest in 1913 enabled the crops to make a good start and carry on
until a heavy rainfall began on June 3. Prospective yields were
somewhat reduced by a dry spell in July when small grains were
filling. Corn did'not lack for water at any time during the season
and matured without material injury from frost. Frost-free
period, 145 days.

Crop year 1915
Precipitation:

Annual, 11 per cent below

Seasonal, 7 per cent below

Crop yields:

Barley, 33 per cent above

Spring wheat, 49 per cent above

Oats, 32 per cent above

Corn, 44 per cent below

The precipitation was slightly below normal, but the tem-
perature was low. Small grains suffered from a lack of rainfall
in the latter part of July and in August until they were harvested,
about the middle of the month. Late spring frosts, continued
low temperatures until August, and drought in that month
resulted in a very poor and immature corn crop. Frost-free
period, 89 days.

Crop year 1916
Precipitation :

Annual, 26 per cent above

Seasonal, 19 per cent above

Crop yields:

Barley, 93 per cent above

Spring wheat, 72 per cent above

Oats, 102 per cent above

Corn, 70 per cent above

Corn was of good quality and fairly well matured.

period, 119 days.

Crop year 1917

Precipitation :

Annual, 15 per cent below

Seasonal, 46 per cent below

Crop yields:

Barley, 46 per cent below

Spring wheat, 36 per cent below

Oats, 51 per cent below

Corn, 32 per cent below

Frost-free

The precipitation of May, July, and August combined was
only 0.66 inch. As a result of "the drought the yields of all
crops were much below their averages. Frost-free period,
146 days.

Crop year 1918
Precipitation:

Annual, 22 per cent below... _

Seasonal, 10 per cent below

Crop yield-:

Barley, 83 per cent below

Spring wheat, 74 per cent below

Oats, 82 per cent below

Corn, 36 per cent above.

There was no reserve water in the soil, and the ample precipi-
tation of about the middle of April could not overcome the

deficient precipitation of May and the still greater deficiency of
June. The July and August precipitation made the corn crop.
Frost-free period, 110 days.

Crop year 1919

Precipitation:

Annual, 11 per cent above

Seasonal, 6 per cent below

Crop yields:

Barley, 80 per cent below

Spring wheat, 75 per cent below

Oats, 83 per cent below

Corn, 35 per cent below

Climatic conditions were unusual. The spring was late and
cold. Annual precipitation was 11 per cent above the mean;
the seasonal precipitation only 6 per cent below. February,
March, April, and May precipitations were above the mean, and
June only slightly below, but there was no adequate rain after
July 10. Frost-free period, 149 days.

Crop year 1920

Precipitation:

Annual, 1 per cent below

Seasonal, 5 per cent below

Crop yields:

Barley, 31 per cent below

Spring wheat, 32 per cent below

Oats, 37 per cent below

Corn, 55 per cent below

A rain of 2.3 inches on June 22 came with such force that it
puddled the ground, beat down the crops, and largely ran off.
Yields of small grains were about two-thirds of their averages.
Corn formed but few ears. Frost -free period, 126 days.

RESULTS AT ASSINMBOINE, MONT.

[Altitude, 2,505 feet; 9-ycar period (figs. 4 and 5)]

Climatic conditions: Mean annual precipitation, 12.36 inches;
mean seasonal precipitation, 6.99 inches; mean seasonal evap-
oration, 35.214 inches.

Average frost-free period, 125 days.
Soil: Clay loam, glacial till.

Number of crop yields averaged each year: Winter wheat, 32;
spring wheat, 30; oats, 5S; corn, 48.

Average annual crop yields per acre: Winter wheat, S.6
bushels; spring wheat 13.6 bushels; oats, 26 bushels; corn,
2,763 pounds.

Crop year 1916
Precipitation:

Annual, 62 per cent

above.
Seasonal, 85 per cent
above
Crop vields:

Winter wheat, 349

per cent above.
Spring wheat, 261 per

cent above.
Oats, 255 per cent

above.

Corn, 57 per cent
above.

This was the first crop on land broken in June, 1915, and kept
clean during the remainder of the season. There was some
winterkilling of winter wheat, and the germination of oats was
not uniform. About 90 per cent of the corn matured. All crops
made vigorous growth and none of them suffered from drought
at any time. Frost-free period, 120 days.

Crop year 1917

Precipitation :

Annual, 38 per cent below.

Seasonal, .">:; per cent below

Crop yields:

Winter wheat, 16 per cent In low

Sprint; wheat, 53 per cent below

Oats, HO per cent below

Corn, 62 per cent below

About a third of the winter wheat plats winterkilled and were
reseeded to spring wheat, but this failed. On account of the
drought none of the corn plat s produced grain, although the
geason was long enough to have matured it. Frost-free period.
j 17 daj s.

.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

11

Crop year 1918

Precipitation :

Annual, 3 per cent below

Seasonal, 60 per cent below

Crop yields-

Winter wheat, 29 per cent below...

Spring wheat, 39 per cent below

Oats, 60 per cent below

Corn, 27 per cent below

A precipitation of 5.33 inches in September, 1917, raised the
crop-year precipitation to nearly the mean. The several crops
made yields ranging from 27 to 60 per cent below their averages.
The production of crops of even this size was largely due to the
fact that in the spring the soil was wet to a depth of 2 to 4
feet from the rains of the previous September. Frost-free period,
110 days.

Crop year 1919

Precipitation:

Annual, 24 per cent below

Seasonal, 49 per cent below

Crop yields:

Winter wheat, 57 per cent below

Spring wheat, 76 per cent below

Oats, 90 per cent below

Corn, 84 per cent below

One of the driest years in the history of the station and the
year of lowest production of all crops except winter wheat, which
failed entirely in 1923. Frost-free period, 136 days.

Crop year 1920

Precipitation :

Annual, 13 per cent below

Seasonal, 5 per cent below

Crop yields:

Winter wheat, 46 per cent below. _

Spring wheat, 21 per cent below

Oats, 12 per cent below

Corn, 16 per cent above

The distribution of the precipitation was very good, and there
were no extended periods of severe drought. There was little
water in the soil when spring opened, and the yields were some-
what below normal. Winter wheat winterkilled and was
reseeded to Marquis. The reseeding was late, and the yield
was 46 per cent below the average yield of winter wheat. Ears
set on about half the corn plants but did not mature. Frost-
free period, 143 days.

Crop year 1921

Precipitation :

Annual, 8 per cent above

Seasonal, 21 per cent above

Crop yields:

Winter wheat, 16 per cent below

Spring wheat, 26 per cent below

Oats, 9 per cent below

Corn, 3 per cent above

The yields of winter wheat and corn were reduced by loss of
stand resulting from an attack of the pale western cutworm in
the spring. Frost-free period, 103 days.

Crop year 1922

Precipitation :

Annual, 13 per cent below

Seasonal, 6 per cent below

Crop yield:

Winter wheat, 30 per cent below. .

Spring wheat, 65 per cent below

Oats, 58 per cent below

Corn, 2 per cent below

The precipitation in June was less than a third of the normal,
and the drought at that time was very injurious. The total
yield of corn was about normal, but because of the dry August
there were but few ears. Winter wheat was winterkilled and
killed by pale western cutworms. It was all reseeded to Mar-
quis and because of the later seeding was damaged less by the
June drought than spring wheat and oats sown at the usual
time. Frost-free period, 145 days.

Crop year 1923

Precipitation:

Annual, 20 per cent above

Seasonal, 61 per cent above

Crop yields:

Winter wheat, 100 per cent

below.

Spring wheat, 34 per cent above

Oats, 11 per cent above

Corn, 62 per cent above

The fall of 1922 was so dry that winter wheat was not seeded
until too late to make any fall growth. With unfavorable
spring conditions it was not able to overcome the competition
of Russian thistles, although some plats were reseeded to spring
wheat. Spring wheat suffered somewhat from drought and hot
winds in the early season, but was favored by the heavy rainfall
of June and July and made a crop exceeded only by that of
1916. The season was very favorable for corn, which matured
about 25 bushels of grain per acre. The total yield of corn was
the highest recorded in the nine years' history of the station.
Frost-free period, 135 days.

Crop year 1924

Precipitation:

Annual, mean.

Seasonal, 7 per cent above

Crop yields:

Winter wheat, 52 per cent below

Spring wheat, 18 per cent below

Oats, 23 per cent above

Corn, 33 per cent above

The fall was so dry that none of the winter wheat emerged
until spring, and most of the plats were reseeded to spring
wheat. The reseeded plats were late and failed entirely. The
only winter wheat produced was on fallow and disked corn
ground. Drought became effective about the middle of July,
and spring wheat which did not mature until the middle of
August was injured much more than oats, which matured the
last of July. Corn was injured by hail on August 1, but the
crop matured more than an average yield. Frost-free period,
119 days.

RESULTS AT MOCCASIN, MONT.

[Altitude, 3,960 feet; 17-year period (figs. 6 and 7)]

Climatic conditions: Mean annual precipitation, 17.11 inches;
mean seasonal precipitation, 8.88 inches; mean seasonal evapora-
tion, 33.348 inches.

Average frost-free period, 124 days.

Soil: Rich black prairie loam overlying gravel more or less
cemented by lime deposits.

Number of crop yields averaged each year: Winter wheat, 6;
spring wheat, 25; oats, 31; corn, 29.

Average annual crop yields per acre: Winter wheat, 17.1
bushels; spring wheat, 17.6 bushels; oats, 36.1 bushels; corn
fodder, 4,578 pounds.

Crop year 1908
Precipitation :

Annual, 12 per cent below

Seasonal, 19 per cent above

Crop yields:

Winter wheat (no crop sown).

Spring wheat, 75 per cent below

Oats, 52 per cent below

Corn, 49 per cent below

The land was broken in July, 1907, and the crop of 1908
was the first at this station. Winter wheat was not sown.
Spring grains were sown late and suffered from the drought
which began early in June and continued through the growing
season. Frost-free period, no data.

Crop year 1909
Precipitation :

Annual, 30 per cent above

Seasonal, 23 per cent above

Crop yields:

Winter wheat, 179 per cent

above

Spring wheat, 94 per cent

above

Oats, 85 per cent above

Corn, 107 per cent above

The yields of all crops were among the highest recorded at
this station. Frost-free period, 148 days.

12

MISCELLANEOUS CERCULAE 81, U. S. DEPARTMENT OF AGRICULTURE
MOCCASIN 'MONT.) FIELD STATION

YEAR

L
r

AUG.

SEPT.

OCT.

NOV

DEC

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1907

4

1 47

73

.20

T

T

55

.49

96

.61

73I |

245

20

1439

W.WHEAT
" S.WHEAT- '

4.4

1908

2

2

OATS
CORN tt

I7.S

1908

4

1.18

1.41

6.27

T

.2 2

.90

08

i. ■ . 1
1 22

. cm ,m

1 03

1.34

IO.B m

5 99

2.54

2218

W.WHEAT

47.8

1909

3

S.WHEAT

34.1

2

OATS

66 6

1

~^ HB—

-■

„, , , ,

CORN #

9456.0

1909

■

4.21

447

.49

JO

1 21

£19

.74

10

1.31

240

1.69 I 1.10

18.11

W.WHEAT

22.9

1910

3

1

S.WHEAT

10.6

1

-__

CORN tt

2641.0

1910

4

2.02

2.54

1.36

1 2S

48

58

.55

.54

1.66

2.98

2.55

SO

17 02

W.WHEAT

25.4

1911

3

S.WHEAT

226

2

OATS
CORN tt

51.5
5981.0

■

1

r MJm-z&-

a ■

^_ i _

1911

4 ■ 6.34

1.37

1 94

1 76

68

88

60

81

1.43

3.94

64

1 92

22.31

W.WHEAT
S.WHEAT

12.9

0.0

1912

3

21

OATS

00

1

«*» '

==

— —

—

^i— i^

CORN #

2329.0

1912

4

1.27

1.63

168

.14

06

89

09

20

.79

2 64

4 77

1.12

15 2S

W.WHEAT

27.1

1913

3

S.WHEAT

23.8

2

OATS

64.4

1

CORN tt

4215.0

1913

4

.51

1.01

1.63

33

38

.47

1.35

1.12

1.19

2.91

4.64

.64

'S"£

W.WHEAT

19.4

1914

3

S.WHEAT

18.4

2

OATS

49.S

1

CORN *(

4310.0

aan.i t_

, ,.wM u.

_ m .

. , ,.■

- i 1

. . Mm

.m rr ._

1914

4

.65

in

.74

.64

.21

.76

.08

2.69

1.43

2.12

3.97

3.54

17.94

W WHEAT

35.2

1915

3

S.WHEAT

32.4'

2

OATS

70.7

1

-9L-d

CORN tt

6144.0

■■ 1 1

.. rf

— ■■ ■ i . i .

. , ■»■

aXBl-B

. ■ _■

1915

4

32

2.65

35

1.01

66

.74

1.22

1.33

1.20

2.25

3.97

2.03

1 8 S3

W.WHEAT

0.0

1916

3

S.WHEAT _
OATS

23.2

47.9

2

1

~M~~Io

CORN #

4423.0

1916

4

1.28

1.81

1.00

64

2.39

1.87

1.30

.85

1.18

2.7 9

1.81

.96

17.88

W.WHEAT

0.0

1917

3

S.WHEAT

9 9

2

OATS

16.3

1917

4

.75

251

.62

.09

2.56

2.34

.6 2

.37

.44

2.69

1.55

■■■■il
2.35

ISC?

W.WHEAT

17.6

1918

3

S.WHEAT

20.1

2

OATS

39.6

1

■ ■

CORN #

7152.0

1916

4

1.48

1.25

1.09

1.14

.26

.13

.71

1.20

.17

73

1.08

1.02

10.26

W.WHEAT J 1.9

1919

1

S.WHEAT 3.2

2

OATS 4.1

1

a— 7-B^

^■-1

■ ■

r^a — a

CORN tt f 937.0

1919

4

.29

1.48

1.43

.93

.7 3

.70

.63

39

5.37

2.91

337

.89

19.72

W.WHEAT

5.8

1920

3

S.WHEAT

15.2

2

OATS

31.7

1

H.M.m ■

CORN tt

5565.0

■ ■■■ —

_.■.■*.

BB_ . .

1920

4

133

66

.65

.15

.21

.06

T

30

.50

3.31

2.45

3.87

14,29

W.WHEAT

0.0

1921

3

S.WHEAT

19.6

2

OATS

23.7

1921

4

1.03

1 69

.03

1.4V7

.47

.67

69

L*-^

29

212

1.42

4.43

1.10

15.41

W.WHEAT

25.6

1922

3

S.WHEAT

20.7

2

OATS
CORN n

46 3
4161.0

1

, M , ,

^ m

1922

4

.68

.51

.7 7

1.19

1.51

.17

1.08

.69

.48

2.75

530n

3.20

1833

W.WHEAT

10.4

1923

3

S.WHEAT

22 8

2

OATS

46 5

1

M-J jfcj

CORN tt

6601.0

1923

4

2.68

1.03

-48

.15

.57

-54

.2 7

.86

.87

1.25

33 7

1 39

13.46

W.WHEAT

21.0

1924

3

S.WHEAT

17.6

2

OATS

160

AVERA

1

1.68

1.66

1.25

.70

_ *- 1 — m

.74

.73

62

J35

1 28

269

3.21

1 70

17.11

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

ft Corn foa

o'er in f.

oundi

1

Fio. C— Relations between muual crop yields and precipitation, by five-day, monthly, and prop-year periods, .il the Moccasin (Mont.) Field Station

CHOP YIELDS AND PRECIPITATION IN THE GIIEAT PLAINS AKEA

13

( Moccasin, Mont. )

1912 '09 '20 '16 '23 '10 '18 '15 '17 'II '14 '22 '13 '08 '21 '24 '19

Fig. 7. — Diagram summarizing the relations between rainfall and crop yields atMoccasin, Mont. (See text, p. 11)

Crop year 1910

Precipitation :

Annual, 6 per cent above

Seasonal, 27 per cent below

Crop yields:

Winter wheat, 34 per cent above. _

Spring wheat, 40 per cent below

Oats, 38 per cent below

Corn, 42 per cent below.

The precipitation was deficient during the most of July and
the first part of August. Winter wheat yielded a good crop,
but spring-sown grains and corn, being later, were affected
more by the drought. Frost-free period, 83 days.

Crop year 1911

Precipitation :

Annual, 1 per cent below

Seasonal, 13 per cent below

Crop yields:

Winter wheat, 49 per cent above

Spring wheat, 29 per cent above

Oats, 43 per cent above

Corn, 31 per cent above

In spite of a dry July, winter wheat and oats which matured
before the end of the month made good yields. The drought
was broken on August 1, and spring wheat which did not mature
for another month made a good crop. The yield of corn also
was good. Frost-free period, 135 days.

Crop year 1912
Precipitation :

Annual, 30 per cent above

Seasonal, 11 per cent below

Crop yields:

Winter wheat, 24 per cent below

Spring wheat, 100 per cent below

Oats, 100 per cent below

Corn, 49 per cent below

The heavy precipitation of August, 1911, made the crop-year
precipitation for the year ending July 31, 1912, the highest in the
the record, but the seasonal precipitation was 11 per cent below
the mean. Crops were badly damaged in the last 15 days of
June by drought. Hail on July 11 destroyed the spring-sown
small grains. Winter wheat wTas further developed. It was
severely injured but matured a crop 24 per cent below the mean.
Corn recovered sufficiently to produce half its average yield of
fodder. Frost-free period, 126 days.

Crop year 191S

Precipitation:

Annual, 11 per cent below

Seasonal, 5 per cent above

Crop yields:

Winter wheat, 59 per cent above

Spring wheat, 35 per cent above

Oats, 78 per cent above

Corn, 8 per cent below

The yields of small grains were from 35 to 78 per cent above
their means. The lower yield was from spring wheat, which did
not mature until August 24 and was affected the most by the
dry weather after the middle of July. Frost-free period, 113
days.

Crop year 1914
Precipitation :

Annual, 2 per cent below

Seasonal, 6 per cent above

Crop yields:

Winter wheat, 13 per cent above

Spring wheat, 5 per cent above

Oats, 37 per cent above

Corn, 6 per cent below

Conditions were ideal for plant growth until about July 10.
From that time until harvest, conditions were most adverse.
Small-grain harvest ranged from August 2 for oats to August 15
for wheat. In spite of the fact that the drought preceding

14

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
HUNTLEY (MONT.) FIELD STATION

|3
YEAR J

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1911

4
3
2

1.05

.57

.88

.82

.13

.27

.21

.41

2.00

244

1.64

2.75

13.17

W.WHEAT
S.WHEAT

7.3

1912

1912

1
4

1.39

237

3.25

.75

.00

.29

*- M 1_

.10

40

43

1.27

2.20

1.10

14.15

CCCS
W.WHEAT

16.7
36.0

1913

3

S WHEAT

18.2

2

OATS

45.6

1

■ -■ .

B ■ B

_ x ^

CORN

27.3

1913

i

119

1.43

2.69

.45

.17

.1 1

.19

.52

1.16

2-83

331

.05

14.30

W.WHEAT

33.2

1914

3

S.WHEAT

24.8

2

OATS

56.7

1

*^

7^

CORN

21.S

1914

4

.76

1.90

1.07

.07

.24

.41

.02

.78

.23

2.50

5.99

3.11

17.08

W WHEAT

38.1

1915

3

S.WHEAT

35.6

2

OATS

78.9

1915

4

.50

1.64

.31

1.34

.71

.46

.24

1.02

.89

1.61

2.11

1.50

12.53

CORN
W.WHEAT

39.0
18.0

1916

3

S.WHEAT

14.2

2

OATS

28.6

1

g- iJ

— i |

CORN

20.4

1916

4

.39

1.16

1.34

1.07

1.50

.76

.49

1.41

1.01

2.88

2.-5

.V7

15.13

W.WHEAT

16.5

1917

3

S.WHEAT

12.1

2

OATS

23.4

1

—

-H — —

— — =^Bl— — 1

CORN

27.5

1917

4

.24

.83

.75

.07

3.58

2.42

.33

.59

• 67

2-09

1.20

1.29

14.06

W.WHEAT

13.7

1918

9

S.WHEAT

14.2

2

OATS

24.1

1

_,_, , ,

CORN

22.9

1918

4

1.18

1.87

.53

1.20

.09

.22

.35

.67

.54 '

.83

.21

.63

8.32

W.WHEAT

5.6

1919

.1

S.WHEAT

0.8

2

OATS

0.8

i

— 1

—

CORN

0.0

1919

4

.63

2.47

2.61

1.96

1.10

.7 5

1.28

1.17

2.03

2.47

2.46

1.58

20.51

W.WHEAT

28.7

1920

3

S.WHEAT
OATS

12.4

30.2

2

■

■

1

m-TTTT^

tacd

_^s H

-■

-Hhs

Kr^

JE — =

LJsL

CORN

20.2

1920

4

1.01

32

.20

.05

.46

.25

30

1.38

.72

3.85

2.19

.83

1158

W.WHEAT

11.4

1921

3

S.WHEAT

9.8

2

OATS

19.4

m I

1

, ■ j ■

, <_ . .

■ ■ ,

■ , i _

JtaJ-

CORN

1.0

1921

4

.19

.66

.21

1.72

.30

1.75

£>0

.30

3.55

2.65

4.68

1.75

1836

W.WHEAT

27.3

1922

3

S.WHEAT

24.3

2

OATS

55.7

1

... ■

CORN

264

1922

4

.84

.34

49

1.27

1.53

.18

.18

.43

1.48

1.66

2.60

3.17

14.17

W.WHEAT

18.6

1923

3

S.WHEAT

11.4

2

OATS

26.0

1

CORN

9.0

1923

4

2.16

4.29

1.15

.10

.66

.53

.56

2.26

.87

1.55

2.48

1.59

18.20

W.WHEAT

28.4

1924

3

S.WHEAT

28.3

2

OATS
CORN

55.0
36.0

AVERA

GE

.89

t.57

1.21

.84

.81

.65

36

.87

L20

222

2.60

1.52

14.76

MONTH

AUG.

SEPT

OCT.

NOV

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fio. 8— Relations between annual crop yields and precipitation, by live-day, monthly, and crop-year periods, at the Huntley (Mont.) Field Station

harvest ripened the crops prematurely and prevented them from
filling well, the yields were above the averages. Frost-free
period, 123 days.

Crop year 1915

Precipitation:

Annual, 5 per cent above

onal, 25 per cent above

Crop yields:

Winter wheat, 106 per cenl above

Spring wheat, 84 per cent above.

< ):ii . 96 per cent above. - --

Corn, 34 per cent above

The distribution of the rainfall was all thai could It asked.
yields were obtained with all crops under all methods.

The only vear that equaled or exceeded it in production was
1909. Frost-free period, 129 days.

Crop year 1916

Precipitation:

Annual. 10 per cent above

Seasonal, 7 per cent above.

Crop V telds:

Winter wheat, 100 per cent

In-low .

Spring wheal, 32 per cenl above

Oats, :>•* per cent above

Corn, -i per cent below

All winter Wheal winterkilled. From July] 5 until harvest,
spring grains Buffered more or less from lack of water but made
good yields. Frost-free period, 120 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

15

BUSHELS
INCHES

39
36
33
30
27
24
2

18

15

12

9

6

3

(Huntley, Mont. )

1

/

/

/
/

1

/

r-

J^

\\ ""

/ 1 \ - -

PI

=*OP V

'ipi n^

» — to„*r&'.

i
1

\jS~W. Wheat

L»

ILLUo

Oats — *V

/A\

1
1

\

— '/'/

1\

1 //

\\-M

J-7k-\-

_.

■■■■W.WHEAT MEAN

V
V

V* /IW

// i ! \Vff -

"-S.WHEAT MEAN

Vii//

>Ai

I ^

/ ^

v

vV/X

"^J\

\

Y^-5. M//?eaf

^V c

e as on a/ Rainfc

.•••"x 1 X******i

\\

^ s

'II

V/

1920 *22 '24 '15 *I7 '14 '23 *I3 '18 '12 '16 "21 "19

Fig. 9. — Diagram summarizing the relations between rainfall and crop yields at Huntley, Mont. (See text, p. 18)

Crop year 191',

Precipitation :

Annual, 5 per cent above

Seasonal, 24 per cent below

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, 44 per cent below. .

Oats, 55 per cent below

Corn, 26 per cent below

All winter wheat winterkilled Droughty conditions prevailed
from the middle of June until after harvest, so crop yields were
low all over the Judith Basin. Frost-free period, 140 days.

Crop year 1918

Precipitation:

Annual, 6 per cent above

Seasonal, 13 per cent below

Crop yields:

Winter wheat, 3 per cent above

Spring wheat, 14 per cent above

Oats, 10 per cent above

Corn, 56 per cent above

Cool, dry weather generally prevailed during the spring
months, and crop growth was very slow. June was hot and dry,
and crop prospects were very poor until July 13, when good rains
ensued. Late-maturing crops or varieties were especially bene-
fited by the late rains. Winter wheat came through the winter
with fair stands and made about the average yield. Frost-free
period, 109 days.

Crop year 1919
Precipitation :

Annual, 40 per cent below

Seasonal, 66 per cent below

Crop yields:

Winter wheat, 89 per cent below

Spring wheat, 82 per cent below

Oats, 82 per cent below

Corn, 80 per cent below

The winter of 1918-19 was unusually mild, and winter wheat
came through with the best stand since 1915. The drought
which started in April continued through the summer, and yields
of grains were the lowest ever obtained in the Judith Basin.
Frost-free period, 118 days.

Crop year 1920

Precipitation:

Annual, 15 per cent above

Seasonal, 48 per cent above

Crop yields:

Winter wheat, 66 per cent below

Spring wheat, 14 per cent below

Oats, 12 per cent below

Corn, 22 per cent above

t

The spring of 1920 was the most backward in the history of
the station and was characterized by unusually low tempera-
tures and an abundance of precipitation. The wet spring and
early summer were followed by a drought in July and August
which seriously affected all crops, the crop season as a whole
being from three to four weeks later than usual. Corn was
benefited by rain late in August and was the only crop to pro-
duce a yield above the average. Frost-free period, 126 days.

Crop year 1921

Precipitation:

Annual, 16 per cent below

Seasonal, 14 per cent above

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, 11 per cent above

Oats, 34 per cent below

Corn, 8 per cent below

Winter wheat was winterkilled by a dry and open winter.
The quantity and distribution of precipitation from May 6 to
July 10 was very favorable to crop production. On the latter
date crops were damaged by hail, the greatest injury being to
oats. Exceptionally hot, dry weather followed in July and
August. Frost-free period, 130 days.

16

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
DICKINSON 'N. DAK.) FIELD STATION

YEAR

i

z

AU6.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1906

4

Z.64

2S

.1 4

.87

.76

.80

.14

.39

.3 0

1.38

2.68

4.8 2

15.17

BARLEY

40.2

1907

2

S.WHEAT

31.8

-

OATS

46.8

2 m

i 1 — Bar

r= ,

-TTTTTT7

— —

',,,,_

CORN

0.0

1907

i

1.93

1.22

.04

.02

.22

.28

.73

1.42

1.27

3.7 9

4.06

1.34

16.32

BARLEY

33.5

1908

3

S.WHEAT

30.0

1

OATS

53.4

1

,__ B _

CORN

0.0

1908

4

1.36

1.S5

2.4 7

.7 8

.24

.2 7

.52

.25

.60

6.04. 1 3.02

1.87

18.97

BARLEY

46.4

1909

3

S.WHEAT

36.0

2

OATS

67.8

1

— gj.

m~- J~r

—

CORN

50.0

1909

4

5.54

.72

1.08

.29

1.02

.34

.97

.8 2

1.7 1

1.26

3.0 3

2.35

19.1 3

BARLEY

26.4

1910

3j

2

1

S.WHEAT
OATS

21.7
35.4

PW — r

jj ; ; ;

i 1

CORN

22.0

1910

4

1.46

.49

.84

.1 5

.15

.90

.55

.43

.48

1.63

2.61

1 .29

10.70

BARLEY

9.0

1911

3

S.WHEAT

5.9

2

OATS

8.9

1

■ _ , ■

_ , , _

— | _ m

— ^J

CORN

00

1911

4

1.68

2.53

2.09

.56

.: 2

.41

.1 2

.50

2.61

3.99

2.06

3.90

20.58

BARLEY

0.0

*

1912

3

S.WHEAT

0.0

2

OATS

0.0

■

■

I ■ _ a

Jj

1*^— Tfc^^

-11—

:mfc:-yL_T

CORN

0.0

1912

4

3.7 1

1.81

1.1 5

.18

T

.13

.04

1.22

.59

1.63

1.83

1.26

12.55

BARLEY

31.2

1913

3

S.WHEAT

25.9

2

OATS

55.5

!

-rWr

■

-=

CORN

276

1913

4

2.79

.37

1.04

.43

T

.04

.43

1.27

.80

2.60

7.60

5 sW23-S1

BARLEY

26.6

1914

3

S.WHEAT

r i5.4

2

■

OATS

246

P

1

n ■

■

CORN

19.0

■ I i

^- B

■ ., . ■

.m . >-■

.i i ■ i . .

m i .. .,

■* ■"■

■ m Ml efff

1914

4

2.20

1.21

.42

.25

.29

.07

.1 5

.21

.73

3.98

5.89

3.81

19.21

BARLEY

57.0

1915

3

S.WHEAT

37.0

2

OATS

93.4

- -

1

_ a

-Mm

CORN

0.0

a.' i ■

.Mil

MB .1 1.1

. i .

*mt L 1 1.1.

— ,

..,..,.■"■ a_-G

1915

4

.36

2.17

1.79

1.1 5

.22

.80

.3 2

.47

2.57

2.52

3.80

2.37

18.54

BARLEY

30.1

1916

3

S.WHEAT

23.3

2

OATS

67.2

■

i

1

" " ,-* ■ ■ ■ ■ 1

■ ..■

CORN

17.8

1916

4

1.93

.70

1.1 0

.38

.98

.60

.23

.48

1.18

.36

2.54

1.40

1 1.88

BARLEY

7.7

1917

3

S.WHEAT

126

2

OATS

17.9 j

1

■fca i i_

_ w _

CORN

00

1917

4

1.43

.20

.22

T

.61

.39

.28

.31

2.11

1.S7

1 .61

1.73

10.53

BARLEY

3.8

1918

3

S WHEAT

93

2

OATS

79

1

■

■

CORN

00

,., ■ _

1 HI 1 J

i i m i.

,

n m . . H

.M i M,

.1 M 1 1

— ■ . .

■ «JB

. . — jfrj

H — .

,.m m

1918

4

2.99

.48

.4 2

.10

.30

T

.67

.79

1.14

2.41

.52

.53

10.35

BARLEY

12

1919

3

S.WHEAT

3.8

2
t

OATS
CORN

30
9.7

1919

4

.51

.71

.5 7

.34

.16

.79

.05

.18

.79

1.64

4.16

.1 1 — ta*_Ml

2.81

12.71

BARLEY

25.6

1920

3

S.WHEAT

19.2

2

OATS

38.7

i

,

■Wu

CORN

14.3

1920

4

2.33

1.74

1.1 1

.10

.1 8

.22

.28

1.01

1.02

1.7 8

3.09

1.61

14.4 7

BARLEY

44

1921

3

S.WHEAT

58

OATS
CORN

11.0
90

1

*=l

■"

■-

._ .1

... . ■

_

i —

. — . .

MM — .

h. . \!

■ .■-_

Mnra

■ ■ ■

1921

[4

Z.73

2.1 5

.13

1.0 5

.61

.3 2

.99

.29

1.1 1

1.9 7

■ 6.57

1 .92

19.84

BARLEY

436

1922

t 3

S.WHEAT

300

2
1

OATS
CORN

730
253

■

1922

4

.74

1.23

.58

1.72

.58

.30

.20

.37

1.77

1.24

4.55

4.67

17.95

BARLEY

"279"

1923

3

S.WHEAT

18.1

2

OATS

459

1

CORN

485

1923

4

.82

4.55

77

.31

18

.03

.34

1.11

1 03

1.1 2

3 26

3 03

16.55

BARLEY

246

1924

3

S.WHEAT

217

' 2

OATS

605

1

_.

idm^=

_JJ

, |J ■

CORN

284

AVER/1

0E

2.01

1.37

.87

.48

.37

.37

.39

.64

1.21

2.28

3.49

2.57

16.05

MONTH

AUG.

SEPT

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

• Crop hailed out In 1911
but Included In average

Fio. 10.— Kelutions between annua] crop yields uud precipitation, by flve-duy, luoutlily, and Otop»yeu periods, Bt tlic DickiasoD (N. JDak.) Field Station

_

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

17

(Dickinson, N.Dak.)

1914 '12 '22 '15 MO '09 '16 '23 '24 '08 '07 '21 '20 '13 '17 'II '18 '19

Fig. 11. — Diagram summarizing the relations between rainfall and crop yields at Dickinson, N. Dak. (See text, p. 19)

Crop year 1922
Precipitation :

Annual, 10 per cent below

Seasonal, 2 per cent above

Crop yields: "

Winter wheat, 50 per cent above

Spring wheat, 18 per cent above

Oats, 28 per cent above

Corn, 9 per cent below

The winter of 1921-22 was extremely long and cold, but there
was an abundance of moisture, and the ground was covered with
snow during the greater portion of the time. Winter wheat
survived the winter with little loss. Spring was rather late, but
an abundance of rain was received, especially during June, and
conditions were very favorable to crop growth until the middle
of July. Hot, dry weather prevailed during July and August
and did considerable damage to late-maturing spring grain.
Spring wheat suffered more than oats because it was later.
Corn suffered from the continued late drought more seriously
than the small grains and was also damaged to some extent by
grasshoppers. Frost-free period, 150 days.

Crop year 1923

Precipitation :

Annual, 7 per cent above

Seasonal, 32 per cent above

Crop yields:

Winter wheat, 29 per cent below

Spring wheat, 30 per cent above

Oats, 29 per cent above

Corn, 44 per cent above

11810°— 27 2

Winter wheat was partially winterkilled. An abundance of
precipitation from the middle of May to the end of August with
other climatic factors favorable made conditions almost ideal
for crop growth. Crops apparently did not lack for water at
any time during the season, but all crops were damaged by hail
on July 8. Corn produced the largest ears that have developed
at the station and reached an unusual degree of maturity.
Frost-free period, 119 days.

Crop year 1924

Precipitation :

Annual, 21 per cent below

Seasonal, 22 per cent below

Crop yields:

Winter wheat, 23 per cent above

Spring wheat, mean.

Oats, 56 per cent below

Corn, 14 per cent below

The season and crop year of 1924 were next to the driest in the
history of the station, both the seasonal and crop-year precipita-
tion being about 20 per cent below their respective means. A
very favorable distribution of the rainfall with evaporation and
temperature lower than normal made the year much more
favorable to crop production as a whole than the quantity of
precipitation would indicate, but the lack of water during the
greater part of August and September made conditions very
unfavorable for late crops. A heavy hailstorm on August 5 did
considerable damage to oats and corn, but other crops were
injured to only a slight extent. Frost-free period, 107 days.

18

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

RESULTS AT HUNTLEY. MONT.

[Altitude, 3,018 feet; 13-year period (figs. 8 and 9)]

Climatic conditions: Mean annual precipitation, 14.76 inches;
mean seasonal precipitation, 7.54 inches; mean seasonal evapora-
tion, 32.497 inches.

Average frost-free period, 134 days.

Soil: Clay loam of sedimentary deposit, second bench lying
above irrigation ditch level.

Number of crop yields averaged each year: Winter wheat, 25;
spring wheat, 36; oats, 34; corn, 41.

Average annual crop yields per acre: Winter wheat, 23 bushels;
spring wheat, 16.4 bushels; oats, 34.9 bushels; corn, 20.6 bushels.

Crop year 1912

Precipitation:

Annual, 11 per cent below

Seasonal, 17 per cent above

Crop yields:

Winter wheat (no crop sown) .

Spring wheat, 55 per cent below

Oats, 75 per cent below

Corn, 19 per cent below

The ground was broken in August, 1911. Winter wheat was
not sown. There was little water in the soil at seeding time
in April, but a good rainfall in the latter part of the month and
in May brought on a good stand of most crops and gave them
good growth. A drought during June severely injured small
grains, especially oats and barley, which did not fill properly
and were almost failures. A heavy rain on July 2 came in time
to benefit wheat, which filled fairly well. During the latter
part of July and the month of August drought injured corn,
which was soft and not well filled when harvested. Frost-free
period, 126 days.

Crop year 1913

Precipitation :

Annual, 6 per cent below

Seasonal, 34 per cent below

Crop yields:

Winter wheat, 57 per cent above

Spring wheat, 11 per cent above

Oats, 31 per cent above

Corn, 33 per cent above

The water stored in the soil from the precipitation of the
preceding fall and the very good distribution of the seasonal
precipitation to a large extent overcame the possible ill effects
of the deficiency in the quantity of rainfall. Crops suffered
but little from drought. The yield of winter wheat was excep-
tionally high, because it all followed either fallow or green manure.
This condition was peculiar to this year alone and was incident
to starting rotations. Frost-free period, 142 days.

Crop year 1914

Precipitation:

Annual, 3 per cent below

Seasonal, 3 per cent below

Crop yields:

Winter wheat, 44 per cent above

Spring wheat, 51 per cent above

Oats, 62 per cent above

Corn, 4 per cent above

The distribution of the precipitation was very favorable to
small grains, which grew and matured normally. Corn suffered
from drought in the latter part of its season. Frost-free period,
154 days.

Crop year 1915
Precipitation:

Annual, 16 per cent above

Seasonal, 57 per cent above

Crop yields:

\\ inter wheat, 66 per cent above

Spring wheat, 117 per cent above

Oats, 126 per cent above

Corn, 89 per cent above

All yields of small grains, especially the spring grains and
flax, were good. June was so cool thai the earlj growth of

corn was badly retarded, but there was no drought. The

first kiilini frosl was rather late, and the j ield of corn was high.

Fro i -free period, 154 days.

Crop year 1916

Precipitation:

Annual, 15 per cent below

Seasonal, 16 per cent below

Crop yields:

Winter wheat, 22 per cent below

Spring wheat, 13 per cent below

Oats, 17 per cent below

Corn, 1 per cent below

Throughout the season all crops were free from diseases and
insect pests, but all suffered to a greater or less extent from
drought, and as a result yields were generally low and the
quality poor. Frost-free period, 126 days.

Crop year 1917
Precipitation:

Annual, 3 per cent above

Seasonal, 7 per cent below

Crop yields:

Winter wheat, 28 per cent below.

Spring wheat, 26 per cent below.

Oats, 33 per cent below

Corn, 33 per cent above |_

The spring was late. Crops made satisfactory growth while
the water of the May and June rainfall lasted, but very hot
and dry weather later when the grains were filling made for
generally low yields and poor quality of small grains. In spite
of the very deficient precipitation in July and August, corn
showed practically no signs of drought and gave a yield above
the average in both quantity and qualitv. Frost-free period,
130 days.

Crop year 1918
Precipitation :

Annual, 5 per cent below

Seasonal, 30 per cent below

Crop yields:

Winter wheat, 40 per cent below

Spring wheat, 13 per cent below

Oats, 31 per cent below

Corn, 11 per cent above

Exceptionally heavy snowfall in December and January
brought the crop-year precipitation up to within 5 per cent of
the mean. Because of drought and hot weather in June, small
grains made yields generally lower and of poorer quality than
the average. The condition that injured the small grains fav-
ored corn. The yield of both grain and stover was above the
average, although the yield of grain would have been increased
by more rainfall in July and August. Frost-free period, 13S
days.

Crop year 1919
Precipitation:

Annual, 44 per cent below

Seasonal, 71 per cent below

Crop yields:

Winter wheat, 76 per cent below

Spring wheat, 95 per cent below

Oats, 98 per cent below

Corn, 100 per cent below

Because of the severe drought all crops gave yields so low
that they were practically failures. With the exception of crops
grown after fallow or green manure, nearly all yields wore less
than a bushel to the acre, and in many cases there were no returns
whatever. Many plats did not head. The corn on all plats
dried up without forming grain. Frost-free period, 140 days.

Crop year 1920

Precipitation:

Annual, 39 per cent above

Seasonal, 13 percent above

Crop yields:

Winter wheat. 25 per cent above —

Spring wheat, '_' I per cent below

Oats, 13 per cent below -

Corn, 2 per cent below

The spring was so cold and wet that seeding did not begin
until May 20, much later than usual. The rainfall of May
and June stimulated a beavj growth of straw in all the small
grains. Winter wheat matured early enough to escape the hot
weather and droughl which followed in July and Vugust. Warm.

dry, win.lv weather at the time spring grain-- should have been
filling reduced their yields. The growth of corn was generally
Blow during the summer, but at do time did it appear to Buffer
from drought. The mild open fall permitted an average crop
of good quality to mature. Frost-free perio.l. 113 da

_

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

19

Crop year 1921

Precipitation :

Annual, 22 per cent below

Seasonal, mean.

Crop yields:

Winter wheat, 50 per cent below

Spring wheat, 40 per cent below

Oats, 44 per cent below

Corn, 95 per cent below

The fall of 1920 was so dry that winter wheat did not ger-
minate until the spring of 1921. There was little reserve water
in the soil. The rains of May and June were sufficient for the
current needs of the crops but not to accumulate much reserve.
Drought became critical at about heading time. By July 20
most of the corn was dried beyond recovery. Only a few of the
plats produced any ears. Frost-free period, 118 days.

Crop year 1922

Precipitation :

Annual, 22 per cent above |

Seasonal, 68 per cent above J

Crop yields:

Winter wheat, 19 per cent above J

Spring wheat, 48 per cent above

Oats, 60 per cent above

Corn, 28 per cent above

Rainfall was abundant and well distributed, and at no time
during the growing season were the crops seriously affected by
drought. The growth of straw was so heavy that lodging took
place on many of the plats. Frost-free period, 146 days.

Crop year 1923

Precipitation:

Annual, 4 per cent below

Seasonal, 18 per cent above

Crop yields:

Winter wheat, 12 per cent below

Spring wheat, 30 per cent below

Oats, 26 per cent below

Corn, 56 per cent below

Late planting and a cool spring forced the filling of small
grains into a drought period from June 27 to July 23. Corn
suffered from drought at the same time to the extent that
pollination was very poor. Frost-free period, 149 days.

Crop year 1924

Precipitation :

Annual, 23 per cent above

Seasonal, 14 per cent below

Crop yields:

Winter wheat, 23 per cent above-
Spring wheat, 73 per cent above

Oats, 58 per cent above

Corn, 75 per cent above

Very favorable distribution of the rainfall throughout the
growing season, cool weather, and an abundance of soil water
accumulated during the previous fall combined to make this
one of the best crop years in the history of the station. Frost-
free period, 111 days.

RESULTS AT DICKINSON, N. DAK.

[Altitude, 2,453 feet; 18-year period (figs. 10 and 11)]

Climatic conditions: Mean annual precipitation, 16.05 inches;
mean seasonal precipitation, 9.55 inches; mean seasonal evapora-
tion, 32.516 inches.

Average frost-free period, 113 days.

Soil: Sandy clay loam.

Number of crop yields averaged each year: Barley, 5; spring
wheat, 25; oats, 27; corn, 23.

Average annual crop yields per acre: Barley, 24.6 bushels;
spring wheat, 19.3 bushels; oats, 39.5 bushels; corn, 15.1 bushels.

Crop year 1907

Precipitation :

Annual, 5 per cent below !

Seasonal, 4 per cent below

Crop yields:

Barley, 63 per cent above

Spring wheat, 65 per cent above

Oats, 18 per cent above

Corn, 100 per cent below

The crop of 1907 was the first crop on land broken about
June 1, 1906, and cultivated during the summer. This treat-
ment being equivalent to fallow, the crop had an unusual ad-
vantage of stored water. The average yield of oats was reduced
about 20 per cent by a hailstorm on August 20, while they
were being harvested. Corn did not mature. Frost-free period,
101 days.

Crop year 1908
Precipitation :

Annual, 2 per cent above

Seasonal, 10 per cent above

Crop yields:

Barley, 36 per cent above

Spring wheat, 56 per cent above

Oats, 35 per cent above

Corn, 100 per cent below

Corn was frosted before much of it reached the milk stage.
Frost-free period, 92 days.

Crop year 1909
Precipitation :

Annual, 18 per cent above

Seasonal, 21 per cent above

Crop yields:

Barley, 89 per cent above-
Spring wheat, 87 per cent

above

Oats, 72 per cent above...

Corn, 231 per cent above.

The yields of corn were the highest in the history of the
station. Frost-free period, 147 days.

Crop year 1910

Precipitation:

Annual, 19 per cent above

Seasonal, 13 per cent below

Crop yields:

Barley, 7 per cent above

Spring wheat, 12 per cent above

Oats, 10 per cent below

Corn, 46 per cent above

The yield of corn was well above the mean, but it was not
well matured. Frost-free period, 95 days.

Crop year 1911

Precipitation :

Annual, 33 per cent below

Seasonal, 37 per cent below

Crop yields:

Barley, 63 per cent below

Spring wheat, 69 per cent below

Oats, 77 per cent below

Corn, 100 per cent below

Small grains made a good growth of straw and were promising
until the latter part of June. The July rainfall was deficient,
and only those plats that were fallow in 1910 had sufficient
water remaining in the soil to make a fair crop of grain. Corn
was injured by the drought and was killed by frost August 27.
Frost-free period, 92 days.

Crop year 1912
Precipitation :

Annual, 28 per cent above

Seasonal, 30 per cent above

Crop yields:

Barley, 100 per cent below

Spring wheat, 100 per cent below

Oats, 100 per cent below

Corn, 100 per cent below

Very promising crop prospects were destroyed by hail on
July 11. Frost-free period, 112 days.

Crop year 1918
Precipitation :

Annual, 22 per cent below

Seasonal, 44 per cent below

Crop yields:

Barley, 27 per cent above

Spring wheat, 33 per cent above. _

Oats, 41 per cent above

Corn, 83 per cent above

3

The soil was well filled with water as cultivation began soon
after the hailstorm early in July, 1912. All crops produced
„ood yields. Frost-free period, 112 days.

20

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
MANDAN <N. DAK.) FIELD STATION

YEAR

a

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

-MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1913

4

.77

2.29

1.13

.16

.28

.07

.05

1.89

1.55

3.57

•~ | 1.35

23.79

BARLEY
S.WHEAT

so.e

32.1~"

1914

3

2

OATS

93.7

1

-■"

— _JJL

^tJt

jjf 4Jn8 — 1

CORN

28.3

1914

4

1.89

1.2*

.90

.31

.37

.07

T

.30

1 .11

4.98

6.32

6.48

23.97

BARLEY

52.3

1915

3

S.WHEAT

3S.1

2

OATS

74.6

1

i —

— | lm _

CORN

27.0

1915

4

.63

1.84

1.85

.34

.14

.28

.09

1.88

.93

1.69

2.25

3.55

15.47

BARLEY

27.5

1916

3

S.WHEAT

20.5

[_ 2

OATS

5S.9

1

ll

CORN

37.1

1916

4

2.04

.9 2

.27

.07

1.10

.28

.19

.35

1.87

.35

2.56

1.58

1158

BARLEY

11.5

1917

3

S.WHEAT

14.0

2

OATS

27.7

1

■

CORN

19.7

■r _.IHU

n . i.i.i

i.i i.i <

,. ., ■

. i i.i. _

—

m.i ■ i

m.-MtL.

iiit SHB iimM«m*«^h

1917

4

.89

1.97

.05

.03

.1 9

.20

.11

.45

2.61

2.45

.68

2.47

12.10

BARLEY

13.5

1918

3

S.WHEAT

13.7

2

OATS

24.0

1

^

CORN

34.0

1918

4

2.03

.63

.27

.45

1.02

.08

.80

.83

1.72

3.95

1.1 2

.85

13.75

BARLEY
S.WHEAT

e.e

11.0

1919

3

2

OATS

237

1

=~

. ■ _:

— ■

CORN

24.0

1919

4

1.22

.49

.98

1.19

.25

.52

.20

1.21

.58

1.72

1.85

2.68

12.89

BARLEY

5.7

1920

3

S.WHEAT

5.6

2

(5ATS

12.4

■ _

iE

-|

- ■

m

■ . ..■■

, ■=

J=JI

CORN

6.7

1920

4

1.81

1.29

.25

.37

.21

.18

.09

.79

2.59

3.05

.82

3.38

14.83

BARLEY

0.4

1921

3

S.WHEAT

1.1

2

■

OATS
CORN

5.6
15.8

■

1

Brm 1

E

m , ..■

. i i i _

_. ■

..I i.i ..

■ i i i —

.< ... . ■

«^

Wm« HHm

———■., ■

- fc

1921

4

.25

1.58

1.39

.87

.24

.28

1.55

.52

.66

2.05

3.43

3.17

15.99

BARLEY

30.2

1922

3

S.WHEAT

21.2

2

OATS

52.1

-_|

■

1922

4

■ , 1 ■>!

.32

2.31

.64

1.60

.82

.36

.38

.16

1.85

1.18

1.94

4.12

15.68

BARLEY

15.9

1923

3

S.WHEAT

11.6

2

OATS

23.9

1

-^r^fc

^_^J

.•> 13

CORN

48.5

1923

4

1.15

2.31

.54

.28

.14

.03

.2S

.28

1.68

.41

5.56

2.07

14.70

BARLEY

23.6

1924

3

S.WHEAT

22.1

2

_ 1

OATS

49.6

■ H

.■^T—

U-i

__fc

CORN

46.2

AVERAGE

1.18

1.53

75

.52

.43

.21

.34

.79

1.56

2.31

3.38

2.88

15.88

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fig. 12.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Mandan (N. Dak.) Field Station

Crop year 1914

Precipitation:

Annual, 46 per cent above

Seasonal, 73 per cent above

Crop yields:

Barley, 8 per cent above

Spring wheat, 20 per cent below —

Oats, 37 per cent below

Corn, 26 per cent above

At the end of June, crop growth was exceptionally heavy.
The heavy vegetation suffered some from drought in July.
Destructive hail, rain, and wind on July 26 and 27 badly injured
crops, the damage to oats being estimated at 51) per cent and
to wheat at least 35 per cent. Barley was already in the shock.
Corn matured without killing frost. Frost-free period, 144 days.

Crop year 1915

Precipitation :

Annual, 20 per cent above

Seasonal, 51 per cent above

Crop yields:

I I.i rley, 132 per cent above

Spring wheat, 92 per cent above

Oats, 136 per cent above

Corn, 100 percent below

The season was too short and cool for corn, and that crop did
not mature. Frost -free period, 69 days.

Crop year 1916

Precipitation:

Annual, 16 per cent above

Seasonal, 18 per cent above

Crop yields:

Barley, 22 per cent above

Spring wheat, 21 per cent above

Oats, 70 per cent above

Corn, IS per cent above

The yields of corn and the small grains, oats excepted, ranged
from 18 to 22 per cent above their respective averages, while
oat yields were 70 per cent above. Frost-free period, 62 days.

Crop year 1917

Precipitation:

Annual, 26 per cent below..

Seasonal, 43 percent below

Crop yields:

Barley, 66 percent below.

Spring wheat, 35 per cent below

Oats, 55 per cent below.

Corn, 100 per cent below

Corn did not mature. Frost-free period, 69 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

21

BUSHELS
INCHES

( Man dan , N.Dak.)

51
48
45
42
39
36
33
30
27
24

1

c n

~i nf

\

A-n^r i i

-LUj

\\ ^-Barley

V?

^». ./"^

Seasonal Evaporation

\\

/

\
\

/
/

^^"•x^X

— -\V

.

/
/

\
\

/

/

V

y*"*'''
/

\ \\

r

---^ /

\

\

/
/

( /\ V\

A

s-Oafs

S.Wheat \ \\
1 \ l\ -

/K

f _J

1 \L\\

£\\

*k

sBA/RLEY MEAN

I 1
18

jS^\'\,J

f#7

it

\ i r ",i1

'-OATS MEAN

^^^***^».

■-S. WHEAT MEAN

15

\\ *•' { /

W^

^L

j

J- --^'1***

9
6
3
0-

i

\°v

• ■*// 1

-^. v^

JpS\

\

— :4— \

nal Rainfall \\

~ '"^v

Seaso

//

1

1915 '14 '22 '23 '16 '21 '24 '19 '20 '18 '17

Fig. 13. — Diagram summarizing the relations between rainfall and crop yields at Mandan, N. Dak. (See text, p. 23).

Crop year 1918

Precipitation :

Annual, 34 per cent below

Seasonal, 25 per cent below

Crop yields:

Barley, 85 per cent below

Spring wheat, 52 per cent below

Oats, 80 per cent below

Corn, 100 per cent below

Corn did not mature. Frost-free period, 116 days.

Crop year 1919

Precipitation :

Annual, 36 per cent below

Seasonal, 52 per cent below

Crop yields:

Barley, 95 per cent below.

Spring wheat, 80 per cent below

Oats, 94 per cent below

Corn, 36 per cent below

The drought continued for its third year. The season was the
hottest and driest during the period for which records are avail-
able. The precipitation after May 11 was so scant that the
yields of all crops except corn were the lowest in the station rec-
ords (excepting 1912, when a good crop was destroyed by hail).
Corn matured a crop, but it was below its 18-year average.
Frost-free period, 124 days.

Crop year 1-920

Precipitation :

Annual, 21 per cent below

Seasonal, 2 per cent below

Crop yields:

Barley, 4 per cent above

Spring wheat, 1 per cent below

Oats, 2 per cent below

Corn, 5 per cent below

From June 1 to July 22 the water supply was sufficient for the
needs of small grain, and a heavy growth of straw was produced.
Prospective yields suffered reduction by a hot wind on July 22
and an insufficient water supply after that date. Frost-free
period, 155 days.

Crop year 1921
Precipitation:

Annual, 10 per cent below

Seasonal, 21 per cent below

Crops yields:

Barley, 82 per cent below

Spring wheat, 70 per cent below

Oats, 72 per cent below

Corn, 40 per cent below

Starting with an extremely dry soil in the spring, the seasonal
precipitation was not sufficient for the needs of crops. The
harvest of small grains was the earliest in the history of the
station and the yields among the lowest. Corn matured, but
the crop was light. Frost-free period, 137 days.

/

22

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
edge:i_e:y (n. dak.) field station

YEAR

3

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1905

4

1.71

.85

.24

1.46

T

.13

T

.1 6

1.58

5.59

3.69

3.17

18.58

BARLEY

31.2

1906

3

S.WHEAT

30.»

2

OATS

61.4

1

, , — i

CORN tf

4912.0

1906

4

1.56

1.45

.93

1.05

.65

.4 2

.06

.21

.35

2.23

1.76

2.10

12.77

BARLEY

12.9

1907

3

S.WHEAT

9.1

2

OATS

CORN St

24.9
2420.0

1

KlJt

„ _

^^

1907

4

1.20

2.79

.82

T

T

.04

-65

1.45

1.26

3.47

3.26

1.19

16.13

BARLEY

26.3

1908

3

S.WHEAT

15.9

2

OATS

17.4

1

a . , , B

a , , , ,

CORN tt

2010.0

1908

4

1.97

1.81

1.34

.63

.20

.12

.25

T

.63

4.56

1.97

3.24

16.72

BARLEY

29.2

1909

3

S.WHEAT

27.6

2

OATS

56.0

1

■ > ■ ■»

, , _ .

CORN tt

5O42.0

1HH

p HOJI . .

. i —

K! 1 i i

— mo

M..aSL. ■

1909

4

1.87

1.00

.39

.34

.84

.14

.30

1.20

2.15

.30

1.91

.72

11.16

BARLEY
S.WHEAT

1.9

5.7

1910

3

2

OATS

9.1

1

CORN St

1610.0

^ta. . . .

MB . .

I VI 1 1

■ M.I. [

_

HI

, , , , H . HI .

_ ^j.i ,.

■fl..

1910

4

2.2 1

4.43

.15

.16

.10

.27

.35

.03

1.55

2.7 1

1.22

1.61

14.79

I BARLEY

0.0

1911

3

S.WHEAT

1.9

2

OATS

4.4

t

_ JH ■ ■

CORN St

4630.0

1 l M 1 .

Mf I.I |

1 1 1 Ml

.... ... .

— ~' ■ ■

-

_ U . —

1911

4

4.12

2.92

.6 7

.20

.41

.48

.01

.08

2.7 1

3.23

3.82

5.97

24.62

BARLEY

29.4

1912

3

S.WHEAT

33.9

2

1

OATS

61.9

■J—

, , , , _

,,,.,,'

CORN St

6350.0

1912

4

2.72

2.47

.04

T

.28

.31

.04

.24

1.46

1.44

3.98

2.65

1 5.63

BARLEY

24.2

1913

3

S.WHEAT

226

2

OATS
CORN St

40.7
4268.0

1

■ ~ — :

, — .,

i !_, , —

, , , , ,

, w. , i

- ifa

, _M_ it^t-TB

1913

4

3.74

2.90

3.37

.28

.25

.13

.20

.57

4.88

•1.80

4.00

2.55

24.67

BARLEY

31.1

1914

3

■

S.WHEAT

16.2

■ ■

2

■ 1

OATS

46.0

■ ■

1

att

t — ~ ^~Wst H

, , , , _

— ., , .

-■■_■ ■

CORN tt

4O49.0

1914

4

1.97

.80

.92

.10

.13

.21

.80

.20

1.36

4.47

4.87

3.1 1

18.94

BARLEY

41.5

1915

3

S.WHEAT

36.0

2

OATS

79.7

i 8

M J

_ ,,, ,

_

_ R1

i 1 ^ i~~

— fi m Kh^l

_La

CORN tt

5900.0

1915

4

1.61

2.23

2.78

.26

.30

.91

.16

1.59

1.23

4.16

2.9 1

4.18

22.32

BARLEY

21.5

1916

3

S.WHEAT

8.8

1

2

■

_ ■

OATS

22.5

■

■ ■

1

tz^

Lwm

tj- I-

K-rH

CORN tt

4S25.0

1916

4

2.98

1.02

.36

T

.79

.28

.45

.30

2.02

.22

3.08

2.22

13.72

BARLEY

10.3

1917

3

S.WHEAT

14 2

2

OATS
CORN ~

164
1840.0

1

M

Ljtrli

1917

4

.89

.89

.24

.10

.16

.17

.1 1

.10

2.95

1.21

1.21

3.2 1

11.24

BARLEY

11.3

1918

3

S.WHEAT

15 4

2

OATS

19.6

1

■

CORN «

2879.0

1918

4

2.4-7

.1 6

.38

1.03

.38

.10

.42

.7 3

1.27

4.07

4.64

3.47

19.12

BARLEY

13.8

1919

3

S.WHEAT

2.2

2
1

■

OATS
CORN tt

16.2
43820

i=|

1919

4

.43

.35

1.18

.43

.29

.35

.02

.1 1

■Jh — i i — . —

1.31

3.07

3.44

2.40

13.38

BARLEY

25.4

1920

3

S.WHEAT

9.6

2

OATS
CORN tt

47 3
23830

1

Ltt-tttH

k^aw

.M.< , .

, ,.„ ,.

,,,.,,

1920

4

.58

2.93

.10

.05

.0 5

.10

.16

.99

1.69

3.31

5.76 V

2.6 1

18.33

BARLEY

17.6

1921

3

S.WHEAT

14.8

2

OATS

29 6

1

, , , ,^_

~"i I I i T~

, , , , ,

. _

J^

-H

CORN a

43640

1921

4

1.27

4.01

.62

.30

31

.45

1.05

.55

.76

4.02

2 44

1.34

17.12

BARLEY

--

1922

3

S.WHEAT

22 9

2

OATS
CORN a

34.9
3452.0

1 '■ ' -

AVERA

CC

1.96

1.94

.85

.38

.30

.27

.30

.50

1.72

2.93

3.17

2.69

17.01

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

# Cor* fodder inp

1

x/ids

lia. 14.— Uelations between annual crop yields and preolpltal Ion, bj li\ e-day, monthly, and crop-year periods, at the Edgeloy IN". Dak.) Field Station

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

23

BUSHELS
INCHES

39

36

33

30

27

24

21

18

15

12

9

6

3

( Edgeley, N. Dak. )

£\

\

CROP YIELDS

^ Seasonal Evaporation

/

-

'*•«. L

si

2<

\

/

/

■s /

\ S. Wheat. •?£

"<'

x^-

/f~^

Sm

/

iti

' "+*+ . J>^" Barley

i

A

\N

III

V

x /

J

\

/A\

BARLEYMEAN

■ OATS MEAN
"••5 WHEAT MEAN

1

jan-

wZT i-WTZ

fcc

w

\W \

\

L*^

JV /

1 //

H 1 '

V

ti '

1/ \

/$.

ti»| /A.

-C^/i

^r

\

|\ //

^_\r

fit >

v\

\ "i/

(

^vU^

\/

Seosona/ Ram fa//

%

1

V

i

1914 '12 '16 '19 '15 '06 '21 '22 '09 '08 '13 'II '17 '20 '07 '18 1910

Fig. 15. — Diagram summarizing the relations between rainfall and crop yields at Edgeley, N. Dak. (See text, p. 24J

Crop year 1922

Precipitation :

Annual, 24 per cent above

Seasonal, 21 per cent above

Crop yields:

Barley, 77 per cent above

Spring wheat, 55 per cent above

Oats, 85 per cent above

Corn, 68 per cent above

The feature of the season was the heavy June rainfall. Al-
though the precipitation in July and August was below the
normal for those months, there was enough water available to
mature a crop above the average. Frost-free period, 165 days.

Crop year 1923
Precipitation :

Annual, 12 per centabove_J

Seasonal, 28 per cent
above.
Crop yields:

Barley, 13 per cent above. (

Spring wheat, 6 per cent

below

Oats, 16 per cent above..
Corn, 221 per cent above-

Few special features characterized the year of 1923. Crop
conditions were better than the average, and the yields of all
crops except wheat were above their averages. The yield of
corn was nearly a record breaker, being exceeded only in 1909.
Grain crops were injured some by drying high winds during the
middle of June. Frost-free period, 120 days.

Crop year 1924
Precipitation :

Annual, 3 per cent above

Seasonal, 13 per cent below

Crop yields:

Barley, mean.

Spring wheat, 12 per cent above

Oats, 53 per cent above

Corn, 88 per cent above

The season in general was cool. Grain yields were above the
average, as a result of an unusual supply of water in the soil at
the beginning of the season and cool weather during the ripening
period. Corn was delayed by the cool season so that only 25
per cent of it matured. The yields of wheat were reduced by
root-rot and those of barley by some similar disease. Frost-free
period, 125 days.

RESULTS AT MANDAN, N. DAK.

[Altitude, 1,644 feet; 11-year period (figs. 12 and 13)]

Climatic conditions: Mean annual precipitation, 15.88 inches;
mean seasonal precipitation, 10.13 inches; mean seasonal evapo-
ration, 34.211 inches.

Average frost-free period, 133 days.

Soil: Sandy loam, bench land about 100 feet above Heart
River. Duplicate plats on heavy clay, glacial till.

Number of crop yields averaged each year: Spring wheat, 67;
oats, 66; barley, 23; corn, 60.

Average annual crop yields per acre: Spring wheat, 17.1
bushels; oats, 40.3 bushels; barley, 21.8 bushels; corn, 29
bushels.

Crop year 1914-
Precipitation :

Annual, 50 per cent above

Seasonal, 69 per cent above

Crop yields:

Spring wheat, 88 per cent above

Oats, 133 per cent above

Barley, 132 per cent above

Corn, 2 per cent below

The crop of 1914 was the first one grown on the station and
was on land broken early in 1913. The season was exceptionally
favorable to plant growth and development. The precipitation
was abnormally high. The rainfall of 10.68 inches in June is
the highest ever recorded here for a single month. Frost-free
period, 104 days.

24

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1.915

Precipitation :

Annual, 51 per cent above

Seasonal, 86 per cent above

Crop yields:

Spring wheat, 105 per cent above. .

Oats, 85 per cent above

Barley, 139 per cent above

Corn, 7 per cent below

Low temperatures prevailed during the growing season. It
was characterized as very favorable to crops in general through-
out the State, with yields the most bountiful in its history.
The yield of corn was good, but the season was too cool for the
best results with that crop. Frost-free period, 138 days.

Crop year 1916

Precipitation:

Annual, 3 per cent below

Seasonal, 17 per cent below

Crop yields:

Spring wheat, 20 per cent above

Oats, 38 per cent above

Barley, 26 per cent above

Corn, 28 per cent above

Crops did not suffer materially for water at any time during
the season. Hot weather when small grains were filling undoubt-
edly reduced their yields somewhat, but was beneficial to corn.
Frost-free period, 122 dayrs.

Crop year 1917

Precipitation :

Annual, 27 per cent below

Seasonal, 37 per cent below

Crop yields:

Spring wheat, 18 per cent below

Oats, 31 per cent below

Barley, 47 per cent below

Corn, 32 per cent below

The season was one of very low precipitation, with extremely
hot weather during the growing period. The production of fair
yields was attributed to the facts that the seasonal rainfall was
supplemented to some extent by water stored in the soil and that
the early dry weather tended to check the development of heavy
vegetative growth. Frost-free period, 122 days.

Crop year 1918

Precipitation:

Annual, 24 per cent below

Seasonal, 19 per cent below

Crop yields:

Spring wheat, 20 per cent below

Oats, 40 per cent below

Barley, 38 per cent below

Corn, 17 per cent above

The season was without as much hot weather as 1917. The
behavior of the crops was much the same as in 1917. The yield
of corn was somewhat better, as it was especially benefited by
: he rains that came in the latter part of July. Frost-free period,
131 days.

Crop year 1919
Precipitation:

\mmal, 13 per cent below

Seasonal, 25 per cent below

Crop yields:

Spring wheat, 36 per cent below

Oats, 41 per cent below

Barley, 60 per cent below

Corn, 17 per cent below

The season opened quite favorably, with good rains in April
and during the first half of May, providing plenty of water fer-
tile immediate needs of all crops. After the middle of Maj the
weather turned hot and dry and continued so throughout the
iimmer. High south wind's were frequent. With do reserve
wafer in the soil for crops to draw on, their yields were light.
Frost-free period, 123 days.

Crop year 1920

Precipitation:

Annual, 19 percent below - —

Seasonal, 33 per cent below

Crop yields:

Spring wheat, 67 per cent below

Oats 69 per cent below

Barley, 74 per cenl below.

Coin, 77 per cent below..

The season opened with conditions favorable to starting prac-
tically all crops, but with no reserve of water in the soil except
in fallow. Frost-free period, 154 days.

Crop year 1921

Precipitation:

Annual, 7 per cent below

Seasonal, 3 per cent below

Crop yields:

Spring wheat, 94 per cent below

Oats, 86 per cent below

Barley, 98 per cent below

Corn, 45 per cent below

The wTorst crop failures in the history of the station were
recorded. A shortage of rainfall in June and high temperatures
during the last few days of the month blighted most grains so
severely that but little development took place thereafter.
Drought became apparent about the middle of June and was
not effectually broken until July 25. Corn tasseled during this
period and the set of ears was poor. Frost-free period, 139 days.

Crop year 1922

Precipitation:

Annual, 1 per cent above

Seasonal, 8 per cent below

Crop yields:

Spring wheat, 24 per cent above

Oats, 29 per cent above

Barley, 39 per cent above

Corn, 9 per cent above

The precipitation did not differ materially in total amount for
either the season or the crop year from that in 1921, but a better
distribution, together with more moderate temperatures and
lower evaporation, made it much more efficient. Small grains
were retarded in April and May, but were brought back to normal
by the rainfall of June and July. The maturity of corn was
hastened and its yield reduced by drought in August. Frost-
free period, 165 days.

Crop year 1923

Precipitation:

Annual, 1 per cent below

Seasonal, 10 per cent below

Crop yields:

Spring wheat, 32 per cent below

Oats, 41 per cent below

Barley, 27 per cent below

Corn, 67 per cent above

During May and June the precipitation was below normal and
the yields of small grains were reduced below their respective
averages and below the yields of 1922. The precipitation for
July was above normal, and the yield of corn was the highest
obtained at this station. The yield of wheat was somewhat
reduced by rust. Frost-free period, 143 days.

Crop year 1924

Precipitation:

Annual, 7 per cent below

Seasonal, 4 per cent below

Crop yields:

Spring wheat, 29 per cent above

Oats, 23 per cent above

Barley, 8 per cent above

Corn, 59 per cent above

The season of 1924 was one of the most favorable to crop
production that the Missouri slope had experienced for a number
of years. The rather late, cool season and a high June rainfall
allowed all crops to produce high yields. Frost-free period, 125

days.

RESULTS AT EDGEI.EY, N. OAK.
[Altitude, 1,561 feel I I and 15)]

Climatic condition-: Mean annual precipitation, 17.01 inches;
mean seasonal precipitation, 10.51 inches; mean seasonal
evaporation, 29.4S2 inches.

Average frost-free period. 126 days.

Soil: ('lay loam of glacial origin overlying decomposed Pierre
shale.

Number of crop yields averaged each year: Barley, ">; spring

wheat. 28; oats, 28; corn. 25.

\verage annual crop yields per acre-: Barley. 20.5 bushels;
spring wheat, Hi.'.) bushels; oats, 34.6 bushels; corn, 3,825

pouni l

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

25

Crop year 1906

Precipitation :

Annual, 9 per cent above

Seasonal, 33 per cent above

Crop yields:

Barley, 52 per cent above

Spring wheat, 83 per cent above

Oats, 77 per cent above —
Corn, 28 per cent above-

As a rule, all crops made good stands and ripened uniformly.
Corn ripened early enough to escape killing frosts and made a
good yield for the section. Frost-free period, 131 days.

Crop year 1907

Precipitation:

Annual, 25 per cent below r

Seasonal, 39 per cent below

Crop yields:

Barley, 37 per cent below

Spring wheat, 46 per cent below

Oats, 28 per cent below

Corn, 37 per cent below

There was little rain during the growing season. Just previous
to ripening time hot dry winds injured the small grains. A hail-
storm on July 13 did some damage to small grains and hurt the
corn very appreciably. No ears were matured on the corn.
Frost-free period, 85 days.

Crop year 1908

Precipitation:

Annual, 5 per cent below

Seasonal, 13 per cent below

Crop yields:

Barley, 28 per cent' above

Spring wheat, 6 per cent below

Oats, 50 per cent below

Corn, 47 per cent below

The spring was cold, with late freezes, and stands especially
of oats were poor and spotted. Growth in June was good, but
dry hot weather from about July 10 until harvest reduced yields.
The relatively poor yield of oats was due to the greater injury
done it by the spring freezes and the hot winds preceding harvest.
The relatively high yield of barley was due to its earlier maturity.
Corn was nearly a failure. The stand was poor, and late re-
planting was necessary. A hailstorm on August 11 stripped
the leaves from the corn and nearly stopped all further growth.
No ears matured. Frost-free period, 143 days.

Crop year 1909

Precipitation :

Annual, 2 per cent below

Seasonal, 1 per cent below

Crop yields:

Barley, 42 per cent above

Spring wheat, 63 per cent above

Oats, 62 per cent above

Corn, 32 per cent above

The prospective yields of small grains were decreased some-
what by hot dry winds just before the middle of July. Corn
was mature September 9. Frost-free period, 137 days.

Crop year 1910

Precipitation:

Annual, 34 per cent below

Seasonal, 52 per cent below

Crop yields:

Barley, 93 per cent below

Spring wheat, 66 per cent below

Oats, 73 per cent below

Corn, 58 per cent below .

The crops were injured and their early growth checked by
cold weather and heavy frosts after they came up in the spring.
Only nubbins set on the corn, and these did not develop. Frost-
free period, 102 days.

Crop year 1911
Precipitation:

Annual, 13 per cent below

Seasonal, 33 per cent below

Crop yields:

Barley, 100 per cent below

Spring wheat, 89 per cent below j

Oats, 87 per cent below [

Corn, 21 per cent above I

The rainfall was poorly distributed, with particularly marked
deficiency in June and July. The heavy rainfall of August

enabled corn to make a fairly good crop of fodder, but only a
few ears matured. Frost-free period, 143 days.

Crop year 1912
Precipitation :

Annual, 45 per cent above

Seasonal, 50 per cent above

Crop yields:

Barley, 44 per cent above

Spring wheat, 101 per cent above

Oats, 79 per cent above

Corn, 66 per cent above

Temperatures and evaporation were low, and the precipitation
was more than sufficient for the needs of the crops. At no time
did they suffer from a lack of water. The season was too cool
to mature corn. Frost-free period, 132 days.

Crop year 1913
Precipitation:

Annual, 8 per cent below

Seasonal, 9 per cent below

Crop yields:

Barley, 18 per cent above

Spring wheat, 34 per cent above

Oats, 18 per cent above

Corn, 12 per cent above

u

Small grains suffered from a lack of water in the first half of
June and again in the latter part of July and the first of August.
Corn matured on all the plats. Frost-free period, 107 days.

Crop year 1914

Precipitation:

Annual, 45 per cent above

Seasonal, 26 per cent above

Crop yields:

Barley, 52 per cent above

Spring wheat, 4 per cent below

Oats, 33 per cent above

Corn, 6 per cent above

Yields were reduced by drought, rust, and hail in the period
immediately preceding harvest. The greatest damage from
hail was suffered by oats and corn, and from rust by wheat.
Frost-free period, 133 days.

Crop year 1915
Precipitation:

Annual, 1 1 per cent above

Seasonal, 31 per cent above

Crop yields:

Barley, 102 per cent above

Spring wheat, 113 per cent above

Oats, 130 per cent above

Corn, 54 per cent above

The spring was dry, but at no time after May 1 was there any
suffering from a lack of water. There was some lodging and rust
in wheat and oats, but yields were the highest obtained at the
station. Corn eared well, but did not mature. Frost-free
period, 120 days.

Crop year 1916
Precipitation:

Annual, 31 per cent above

Seasonal, 19 per cent above

Crop yields:

Barley, 5 per cent above

Spring wheat, 48 per cent below

Oats, 35 per cent below

Corn, 18 per cent above

The low yields and poor quality of wheat and oats were the
result of rust which developed in July with warm humid weather.
At no time was there a lack of water. Corn made a good yield
of fodder and matured some grain. Frost-free period, 135 days.

Crop year 1917

Precipitation :

Annual, 19 per cent below

Seasonal, 28 per cent below

Crop yields:

Barley, 50 per cent below

Spring wheat, 16 per cent below

Oats, 53 per cent below

Corn, 52 per cent below

Crops suffered more or less continuously from drought, and
yields were low. Corn matured no ears and made only a light
yield of fodder. Frost-free period, 106 days.

26

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
SHERIDAN (NA/YO.) FIELD STATION

i a

YEAR! J

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

-

.13

.56

2.85

.90

1.07

.e 4

37

1.31

.63

3.84

1.36

.0 9

13.95

W. WHEAT

9 2

1917

1916

3

S.WHEAT

5.5

2

OATS

23.6

1917

J

.43

■ .> i
.08

1 0 2

.08

.78

1 56

.08

1.65

2.92

3.18

1.54

1.16

14..48

W. WHEAT

346

1913

3

S.WHEAT

24 8

:

OATS

S7.4

1

— ; — t , ,

CORN

3 2 2

1918

A

1.02

2.60

.60

.60

.15

.26

.23

.21

.94

1.01

1.12

.77

3.7-,

W. WHEAT
S.WHEAT

1.»
1.6

1919

3

2

OATS

0.4

'

■ _

L-«—

COBN

0.0

1919

4

.30

1.16

1.80

.62

.14

.46

.38

.49

2.3S

2.68

3.11

1.11

14.60

W. WHEAT

28 0

1920

3

S.WHEAT

23.6

2

■

OATS

52.0

■

'

■

■ ■

CORN

17.3

■ i i i i

L_w^_

21 ^H

■ lit D i ■

. B In

1920

A

.56

.45

1.13

.60

.32 '

.*4

.02

.65

.94

2.08

2.63

1.41

11.23

W. WHEAT

10.3

1921

3

S.WHEAT
OATS"

6.3 _
8.1 '

2

1

CORN

0.6

tm . . M

■ , , .

H. ,_B

.- . . _

i . ■■

i , . i . i

»j_Bl —

AM,

1921

A

JO

.35

.21

1.38

.20

1.27

.19

.35

2.63

2.82

3.48

3.12

16.30

W. WHEAT

27.1

1922

3

S.WHEAT

29.5

2

■

OATS

48.9

w

1

— -

~mM-

L^_

1 Lr^r-

CORN

23.0

1922

A

1.27

.15

1.26

.82

.59

.41

.22

134

2.37

1.95

2.9 4

3.45

16.77

W. WHEAT

17.7

1923

3

S.WHEAT

21.6

2

■

OATS

46.4

■

1

T. : I Hi

.. . ..,

™ ™

M.mM.

CORN

38.9

1923

A

.8 5

I 1.54

.43

.33

.30

1.10

1.06

1.63

1.56

2.12

.98

21.25

W. WHEAT

45.5

1924

3

S.WHEAT

23.3

2

■ 1

OATS

55.1

I 1

1

-JJ -

I

CORN

25.3

AVERAGE

.6 I

1.84

1.33

.68

.45

.69

.32

.88

1.80

2.39

2.29

I.5I

14.79

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY T0TAL
JULr |yeAR

Fig. 16. — Relations between annual crop yields and precipitation, by flve-day, monthly, and crop-year periods, at the Sheridan (Wyo.) Field Station

Crop year 191 S

Precipitation:

Annual, 33 per cent below

Seasonal, 18 per cent below

Crop yields:

Barley, 45 per cent below

Spring wheat, 9 per cent below

Oats, 43 per cent below

Corn, 25 per cent below

The comparatively low yields were the result of drought prior
to July 20. Corn suffered again from a lack of water in the
latter part of August. Frost-free period, 105 days.

Crop year 1919
Precipitation;

Innual, 12 per cent above

Seasonal, 28 per cent above

Crop yields:

Barley, 33 per cent below

Spring wheat, 87 per cent below

Oats, 53 per cent, below

Corn, 15 per cent above

There was some damage from drought and high temperatures,
but rust was chiefly responsible for the low yields of wheal and
pats. Frost-free period, 142 days.

Crop year 1920
Precipitation:

Annual, 21 per cent below

Seasonal, 3 per cent, below

Crop yields:

Barley, 24 per cent above

Spring wheat, 43 per cenl below

Oat-, :;7 per cent above

( "ni, 38 per cent below

Wheal was badly damaged by rust, the loss being estimated

a1 ">H per cent. Corn suffered from drought in the latter part of

ii ea on. Frost-free peri. >< I, 138 days.

Crop year 1921

Precipitation:

Annual, S per cent above

Seasonal, 27 per cent above

Crop yields:

Barley, 13 per cent below

Spring wheat, 12 per cent below

Oats, 14 per cent below

Corn, 14 per cent above

Ideal growing weather prevailed until July 0. Hot dry
weather with high winds from that time until July 27 damaged
small grains and prevented corn from earing. Frost-free period,
141 davs.

Crop year 1922
Precipitation:

Annual, 1 per cent above

Seasonal, 19 per cent below

Crop yields:

Barley (no record).

Spring wheat, 35 per cent above

Oats, 1 per cent above

Corn, 10 per cent below

The yield of oats was reduced by rust. Corn Buffered badly

<luring the greater part of August from a lack of water. Many
of the stalks did not ear at all, and those that did produced
only small nubbins. Frost-free period, 13 1 days.

RESULTS AT SHF.KIDAN, WYO.

[Altitude, 3,724 feet; s-y.-ir period nips. 10 and 17)]

Climatic conditions: Mean annual precipitation, 14.79 inches;
mean seasonal precipitation, 7.0'.» inches; mean seasonal evapora-
tion. 3 1.212 inches.

Average frost-free period. 131 days.

Soil : Clay loam.

Number of crop yields averaged each year: Winter wheat, 23;
spring wheat, 37; oats, 50; corn, 44.

Average annual crop yields per acre: Winter wheat, 21.8
bushels; spring wheat, 17 bushels; oats, 36.S bushels; corn, 1S.G
bushels.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

(Sheridan, Wuo.)

27

24

2

18

I 5

1 2

9

6

3

July

Dorr idit

June

— May
Apr.

— Mar

— A/ov-

^^\^

rnLUI r 1 1 /-\ i iuin

>N- \ ""* „

ANNUAL MEAN —

^N^^—^-^^

LY

~~~~~ ■

^"^N^N^N^-j — JUNE

V\/\|

:^^Jrrr=-^,

ir CROP YEAR
GROWING SEASON
WINTER

FALL

"% >v ^—^____MA Y . ^^^ \l

~T" ' AUG.-SEPT.-OCT.-NOY. """"i""

1924

'23 '22 '20 '18 '17 '21

Fig. 17.— Diagram summarizing the relations between rainfall and crop yields at Sheridan, Wyo.

'19

Crop year 1917

Precipitation :

Annual, 6 per cent below

Seasonal, 26 per cent below

Crop yields:

Winter wheat, 58 per cent below

Spring wheat, 68 per cent below

Oats, 35 per cent below

Corn, 40 per cent below

Crop prospects were very bright until about July 1, when a
drought that began June 1 1 was much in evidence. The drought
was not broken by rain of consequence until October 20. Frost-
free period, 129 days.

Crop year 1918
Precipitation:

Annual, 2 per cent below

Seasonal, 10 per cent above

Crop yields:

Winter wheat, 60 per cent above

Spring wheat, 46 per cent above

Oats, 57 per cent above

Corn, 73 per cent above

Frequent rains during April kept the soil so wet that no
team work could be done on it until the 29th. The soil was
then wet to a depth of about 3 feet. With this reserve in the
soil the precipitation during the growing season was sufficient to
develop all crops normally with little or no suffering from drought,
and the yields were among the best in the history of the station.
Frost-free period, 144 days.

Crop year 1919
Precipitation :

Annual, 34 per cent below |

Seasonal, 52 per cent below

Crop yields:

Winter wheat, 92 per cent below

Spring wheat, 92 per cent below

Oats, 99 per cent below

Corn, 100 per cent below

Small grains began to suffer from drought early in June and
from heat and drought the last 10 days in June, and conditions
were not relieved until they were either harvested or dried up
and died. Corn began to suffer from drought at the tasseling
stage about the middle of July. Frost-free period, 129 days.

Crop year 1920

Precipitation :

Annual, 1 per cent below

Seasonal, 16 per cent above

Crop yields:

Winter wheat, 28 per cent above

Spring wheat, 39 per cent above

Oats, 42 per cent above

Corn, 7 per cent below

The spring was rather backward, the ground being very wet
from the fall rains and the winter snow. Cool weather with
frequent rain or snow during April and May made field work
difficult and slow. There was plenty of water until after the
middle of July. The small grains did not mature until August
and were shrunken considerably by hot weather and a lack of
water during the ripening period. Corn was drying badly when
it was frosted on August 29. It was not fully matured. Frost-
free period, 125 days.

Crop year 1921

Precipitation:

Annual, 24 per cent below

Seasonal, 12 per cent below

Crop yields:

Winter wheat, 53 per cent below

Spring wheat, 63 per cent below

Oats, 78 per cent below

Corn, 97 per cent below

Even fair yields of grain were produced only on land that was
fallowed in 1920. Except on land so treated there was but
little water in the soil in the spring. Sufficient rain fell early in
the season to give all crops a fair start, but the effects of drought
and hot weather were evident on many plats by the middle of

28

MISCELLANEOUS CIRCULAR 81, V. S. DEPARTMENT OF AGRICULTURE
BELLEROU RCH EC (S. DAK.) FIELD STATION

year] i

AUG.

SEPT.

OCT.

NOV.

DEC*

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1907

J

1.07

2.13

T

T

.44

.20

.19

1.65

I.I 6

3.95

1.47

1.26

13.52

V. WHEAT
S. WHEAT- "

21 7

1908

9

z

OATS

32.4

•

■ ■

^*1 —

. . ■

— I"

- - L_L — —

CORN

1908

4

.62

.52

2.03

.20

.9 1

.17

.23

.19

.84

3.87 i ^.59

2.45

17 62

W.WHEAT

28.9

1909

3

S.WHEAT

28.7

Z

OATS

609

1

B ,

■ — ! — H — i —

_ ,

CORN

19.3

1909

4

.55

1.07

.76

.73

1.28

.73

.7 0

.93

! 57

1.26

1.51

1.4 2

12.51

W.WHEAT

I.S

1910

;

S. WHEAT

2.6

2

OATS

6.8

i

-= —

B ,

.m < , ,

BL^-

_ _ t _

^^■~

CORN

0.6

1910

4

1.03

2.92

.27

.1 1

.1 0

.13

.05

.09

.17

.45

.50

.80

6.62

W.WHEAT

0.0

1911

3

S. WHEAT

00

2

■

OATS

0.0

ft

1

ju_»:

fcj

CORN

0.0

1.86

.92

.39

.98

.30

.24

.10

.7 1

2.3 2

2.26

.29

3.20

13.57

W.WHEAT
S.WHEAT

0.0
0.0

1912

1911

3

2

■

OATS

8 2

■

■

••

-^ .

=-r-; -

-

.....

-1 —

|~jflr

t— J-fcz

CORN

21.9

1912

«

2.60

3.1.9

.51

.04

.13

.57

.24

.99

.25

i.98

3.10

35

14.45

W.WHEAT

21.3

1913

5

S.WHEAT

10.8

2

OATS

23.9

<F

S" ■ ■

■ .■ - m

— . a.

_ . _

!

CORN'

8.6

1913

4

.26

2.38

1.86

.10

.45

T

1.00

.29

1.09

2.22

2.09

1.34

13.08

W.WHEAT

18.2

1914

3

S.WHEAT

10.1

2

OATS

26.3

1

— ■ — B— - — -

— . , , -

CORN

0.5

1914

4

1.12

.35

1.77

.00

.43

.92

1.0 1

.16

2.58

2.32

4.74

5.74

21.14

W.WHEAT

36.2

1915

3

S.WHEAT

57.6

2

OATS

125 6

i

_ It.M

=mJh

a- 9*

CORN

44.5

1915

4

.44

1.26

1.25

.43

.1 7

.36

.2 3

.98

.64

3.17

2.19

2.01

13 13

W.WHEAT

12.7

1916

3

S.WHEAT

17.3

OATS

33.3

2

■

1

_M a

■ ■■

-- ■

.jZjH

iJLd

■ I

CORN

32 5

4

2.02

.20

.99

.33

.23

.92

.74

.27

2.5 1

3.71

.97

.80

13.74

W.WHEAT

3.8

1917

1916

3

S.WHEAT

7.4

2

OATS
CORN

17.1
204

;

— ,

1917

4

1.67

.35

.46

T

.92

.99

.6 4

.81

2.40

1.60

1.17

3.4 1

14.42

W.WHEAT

27.1

1918

3

S.WHEAT

11.9

2

OATS

23.3

1

[

-jg^

— «

CORN

30.0

1918

4

2.99

3.08

.22

.15

.85

.04

.57

.87

2.14

1.14

.35

2.59

1499

W.WHEAT

2.0

1919

3

S.WHEAT

0.9

2

OATS

2.3

|

1

Bfcstsl

=

■— wi

CORN

03

1919

4

1.02

1.20

2.49

1.22

.62

.65

.1 6

1.35

2.59

5.90

2.53

28.08

W.WHEAT

1.6

1920

3

_M_8.35

S.WHEAT

29.9

2

OATS

638

■-■ ■

> 1

■ ....■

-m= =

— m~r

t J -(-

^^M —

™. ^.. '8

■ ■ - ■— ■
- ■ — ■■ B

CORN

37.4

1920

4

.56

.63

1.67

.55

05

.29

T

.84

.72

1.44

3.36

2.30

13 3 1

W.WHEAT

5.4

1921

3

S.WHEAT

7.3

2

OATS

11.6

1

CORN

90

1921

4

.52

.72

.10

.30

.50

1.3 1

.38

.20

2.84-

3 ■■■:

3.74

6.52

:r 55

W.WHEAT

30.8

1922

3

S.WHEAT

322

2

OATS
CORN

66.0
42 3

■ ~P

1

...Hi ,

■

■ ■ •-' ' ■

! il l "n II

. ■.■■_■.

... «

. . — MtfT

m »F" ■ — -

1922

4

.90

T

.79

2.82

.24

.22

.23

.32

.82

2.31

3.81

454

17.00

W.WHEAT

2 1 3

1923

3

S.WHEAT

280

2

1

1

OATS

57.5

1 |

J

. .JL H .1

CORN

52.4

1923

•4

5.35

5.95^ 3.14

2'

.41

.08

.88

.70

.81

.68

1.27

1.22

20.76

W.WHEAT

30 5

1924

3

■

S.WHEAT

21.5

■

2

■

OATS

44.1

n- 5=^5 8 w

_«■,

CORN

17.7

■

■ - - ■-

. . . . ■

a — .

AVERAGE

1.46

1.60

110

.48

.53

.46

.43

.67

1.50

2 60

2.47

2.50

15.80

MONTH

AUG.

SEPT.

OCT

NOV

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fio. 18.— Relations between annual crop yiclUs and precipitation, by live-day, monthly, and crop-year period.-;, al the Bellefourcbe (S. Dak.) Field Station

CROP YIELDS AND PRECIPITATION- IN THE GREAT PLAINS AREA

29

fiUSHELS
INCHES

( Bellefourche, 5. Dak.)

60
57
54
5 1
48
45

A?

r

:ROF

L

J YIL i_u>o

/

Seasonal tvaporation

/

/

39
36
33
30
27
24
2 1
1 8

/W

\
\

/

»».

y

/

s

V

S

<

\

/

/

1 1

^

\/

X
\

*

\
\

y

>-

/

1 i

>l

Oats

/ I

\ "n

Y

\ /

yf-

1

\
\

•

k^eo

1

\

\

/
/

r

o.

i

HI

Li-l 1

/

Y

...OATS MEAN

-5. WHEAT MEAN

W. WHEAT MEAN-

1 5
1 2

9

6

3

n.

'X

f^~

~~ /— rri — ■ 7A\ i js>/'\

XJ

1 1

\V

//^

Ns*

/'

\

A

/ Seas

/ /

v\-4

A

**-— -i^S&

on a/ R

ainfai

'/ \

i/T

li

f

^*^^.

•

V

N^

1920 '15 '24 '22 '09 '23 '19 '13 '18 '17 '12 '08_ '21 '16 '14 '10 Ml

Fig. 19. — Diagram summarizing the relations between rainfall and crop yields at Bellefourche, S. Dak. (See text, p. 30)

June. The rainfall for the remainder of the season was not suffi-
cient for the needs of growing crops. The heavier precipitation
came in dashing showers from which there was considerable
run-off. Some damage was done by grasshoppers that came in
from the surrounding grassland. Frost-free period, 121 days.

Crop year 1922

Precipitation :

Annual, 10 per cent above

Seasonal, 51 per cent above

Crop yields:

Winter wheat, 24 per cent above

Spring wheat, 74 per cent above

Oats, 34 per cent above

Corn, 24 per cent above

Crops did not suffer severely from a lack of water at any
time during the season. Good yields were produced by nearly
all methods of preparation. The relatively low yield of winter
wheat in comparison with spring wheat was due to unfavorable
fall conditions, as a result of which it did not emerge until spring
and then with a rather poor stand. The prospective yields of
both oats and corn were considerably reduced by a hail and wind
storm July 23. Frost-free period, 141 days.

Crop year 1923

Precipitation:

Annual, 13 per cent above

Seasonal, 34 per cent above

Crop yields:

Winter wheat, 19 per cent below .
Spring wheat, 27 per cent above-
Oats, 27 per cent above

Corn, 109 per cent above

L

There was more than the usual contrast in the results from
different methods of tillage, yields ranging from poor to very
good with the grain crops. The yields of corn and all forage
crops were good. The average yield of winter wheat was good,
although it was below the normal. Small grains suffered from
drought at times during June and July. The heads were not
well filled and the quality of the grain was not as good as usual.
The heavy rainfall of the latter part of July came too late to
benefit small grains, but provided ample water for corn and
other late crops for which the water supply had been sufficient.
Grasshoppers were present in large numbers and did some
damage to all crops. Frost-free period, 149 days.

30

MISCELLANEOUS CLRCULAB 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1924

Precipitation:

Annual, 44 per cent above

Seasonal, 21 per cent below

Crop yields:

Winter wheat, 109 per cent above.

Spring wheat, 37 per cent above

Oats, 51 per cent above

Corn, 36 per cent above

The precipitation during the growing season was light, but
the fall rains in 1923 were exceptionally heavy, and in the spring
the soil was wet to the full depth sampled, 6 feet. Corn suffered
somewhat from a lack of readily available water in its later
stages of growth. Frost-free period, 1 10 days.

RESULTS AT BELLEFOLRCHE. S. DAK.

[Altitude, 2,875 feet; 17-year period (figs. 18 and 19)]

Climatic conditions: Mean annual precipitation, 15. SO inches;
mean seasonal precipitation, 9.07 inches; mean seasonal evapora-
tion, 36.543 inches.

Average frost-free period, 137 days.

Soil: "Gumbo," decomposed Pierre shale.

Number of crop yields averaged each year: Winter wheat, 6;
spring wheat, 30; oats, 32; corn, 27.

Average annual crop yields per acre: Winter wheat, 15.1
bushels; spring wheat, 16.9 bushels; oats, 35.5 bushels; corn,
21.1 bushels.

Crop year 1908
Precipitation :

Annual, 16 per cent below

Seasonal, 14 per cent below

Crop yields:

Winter wheat (no crop sown).

Spring wheat, 28 per cent above

Oats, 9 per cent below

Corn (no record).

The crop of 1908 was the first one on the station and was
grown on land broken in 1907. This preparation was equiva-
lent to fallow. The greater yield of wheat in comparison with
oats was undoubtedly due to the fact that it was earlier and
consequently suffered less from the July drought. Corn had a
good growth of stalks but few ears. Frost-free period, 128 days.

Crop year 1909

Precipitation :

Annual, 12 per cent above

Seasonal, 41 per cent above

Crop yields:

Winter wheat, 92 per cent above. .

Spring wheat, 69 per cent above

Oats, 72 per cent above

Corn, 8 per cent below

Corn made a fair crop, but dry weather late in the season cut
its yield below the average. Frost-free period, 128 days.

Crop year 1910

Precipitation:

Annual, 21 per cent below

Seasonal, 36 per cent below

Crop yields:

Winter wheat, 88 per cenl below

Spring wheat, 85 per cent below

Oats, 81 per cent below

Corn, 97 per cent below

The low vields were the result of drought.
124 da

Crop year 191 1
Pr ( ipitation:

Annual, 58 per cent below

Seasonal, 79 per cent below ..__.

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, lOOpercenl below

Oats, 100 per cent below.

Corn, 100 per cent below

Frost-free period,

The year was the driest in the history of the station, and all
:ro[.s failed completely. Froet-free period, Ml days.

Crop year 1912

Precipitation :

Annual, 14 per cent below

Seasonal, 11 per cent below

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, 100 per cent below

Oats, 77 per cent below

Corn, 4 per cent above

There was no stand of winter wheat, and it was reseeded to
spring wheat. The rains in the first week of July came too late
to save wheat, which had been injured beyond recovery by the
drought that started in the latter part of May and continued
throughout June. Oats and barley survived sufficiently to
produce some grain. Corn made a crop slightly above the
average. Frost-free period, 155 days.

Crop year 1913

Precipitation:

Annual, 9 per cent below

Seasonal, 37 per cent below

Crop yields:

Winter wheat, 41 per cent above

Spring wheat, 36 per cent below

Oats, 33 per cent below

Corn, 59 per cent below

Small grains began to run short of water about the middle of
June and showed injury thereafter. The rain on June 2S came
when the spring grains were heading and saved them from total
failure. Winter wheat was about two weeks farther advanced
and made a good yield. Corn set only a few ears and dried up
in the last half of August. Frost-free period, 142 days.

Crop year 1914

Precipitation :

Annual, 17 per cent below^

Seasonal, 26 per cent below

Crop yields:

Winter wheat, 21 per cent above..

Spring wheat, 40 per cent below

Oats, 26 per cent below

Corn, 97 per cent below

Small grains began to suffer about June 20 and finally dried up
rather than ripened about the middle of July. Winter wheat
was farther advanced and consequently suffered less than spring
grains. Corn was ruined by the continued drought, conditions
for it becoming critical about July 20. Frost-free period, 144
days.

Crop year 1915

Precipitation:

Annual, 34 per cent above. _
Seasonal, 70 per cent above.
Crop yields:

Winter wheat, 140 per cent

above

Spring wheat, 241 per cent [
above \

Oats, 254 per cent above.. \

Corn, 111 per cent above

The season was the most favorable for crop production that
has been experienced in western South Dakota since that section
has been settled. Corn did not all mature fully. Frost-free
period, 119 days.

Crop year 1918

Precipitation:

Annual, 17 per cent below

Seasonal, 12 per cent below

Crop yields:

Winter wheat, 10 per cent below
Spring wheat, 2 per cent above.
Oats, 6 per eetit below

Corn, 54 per cent above

Small grains Buffered from a Lack of sufficient water in July but
made about average yields, The relatively poor yield of winter

wheat was due to winterkilling and to rust. Corn did not suffer

from drought until shortly before harvest. Frost-free period,
120 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

31

Crop year 1917

Precipitation :

Annual, 13 per cent below

Seasonal, 13 per cent below

Crop yields:

Winter wheat, 75 per cent below

Spring wheat, 56 per cent below

Oats, 52 per cent below

Corn, 3 per cent below

The season was unfavorable to small grains but fairly favor-
able to corn and other cultivated crops. The early spring was
so wet and cold that small grains could not be planted until
about three weeks later than usual. From the first week in
June until harvest the rainfall was not sufficient for their needs.
They began to suffer at about the heading stage in the latter
part of June and continued to suffer from drought and excep-
tionally hot weather in July until they were harvested. Winter
wheat suffered in addition from winterkilling, which reduced its
stand and lowered its vitality until it was two weeks later than
spring wheat. Corn was not far enough advanced for the hot
dry weather of July to injure it seriously. August rains cared
for its needs until it was far enough advanced to mature a fair
crop. Frost-free period, 128 days.

Crop year 1918

Precipitation :

Annual, 9 per cent below

Seasonal, 5 per cent below

Crop yields:

Winter wheat, 79 per cent above

Spring wheat, 30 per cent below

Oats, 34 per cent below

Corn, 42 per cent above

There was a marked deficiency of rainfall in June, and spring-
sown small grains suffered severely except on fallow. After the
drought was broken early in July the rainfall was sufficient for
the needs of the crops. Winter wheat did not come up until
spring and was so much later than the spring grains at the time
of the June drought that it was not so badly injured and was
able to make a better recovery when the July rains came. Corn
was not materially injured by the drought and developed
normally. Frost-free period, 119 days.

Crop year 1919

Precipitation :

Annual, 5 per cent below

Seasonal, 31 per cent below

Crop yields:

Winter wheat, 87 per cent below

Spring wheat, 95 per cent below

Oats, 97 per cent below

Corn, 98 per cent below

Crops were almost complete failures. This was the result of
exceptionally hot, windy weather in May and June combined
with a drought lasting from the middle of April to the latter
part of July. Frost-free period, 147 days.

Crop year 1920

Precipitation :

Annual, 78 per cent above

Seasonal, 114 per cent above

Crop yields:

Winter wheat, 89 per cent be-
low

Spring wheat, 77 per cent above

Oats, 80 per cent above

Corn, 77 per cent above

The crop season was one of the most favorable experienced in
western South Dakota. Winter wheat was practically destroyed
by stem rust. The spring-sown small grains would have yielded
still higher than they did if there had been more rain in the
latter part of July or the first of August. Frost-free period, 148
days.

Crop year 1921
Precipitation :

Annual, 16 per cent below

Seasonal, 14 per cent below

Crop yields:

Winter wheat, 64 per cent below

Spring wheat, 57 per cent below

Oats, 67 per cent below

Corn, 57 per cent below

Land cropped in 1920 contained no stored water, and crops on
it suffered from a lack of water at intervals throughout the
season. Land fallowed in 1920 was well filled with water, and
crops on it developed normally and grew to maturity without
suffering severely for -vater for any considerable periods of
time. Winter wheat on fallow was "winterkilled or destroyed
by soil blowing. Frost-free period, 137 days.

Crop year 1922

Precipitation :

Annual, 30 per cent above

Seasonal, 82 per cent above

Crop yields:

Winter wheat, 104 per cent above. .

Spring wheat, 91 per cent above

Oats, 86 per cent above

Corn, 100 per cent above

Continued rains during May, June, and July enabled small
grains to mature without experiencing a shortage of water.
The growth of corn was checked late in August by the exhaus-
tion of available water, but it was far enough advanced to make
a good yield of good quality. Frost-free period, 171 days.

Crop year 1923

Precipitation :

Annual, 8 per cent above

Seasonal, 27 per cent above

Crop yields:

Winter wheat, 41 per cent above

Spring wheat, 66 per cent above

Oats, 62 per cent above

Corn, 148 per cent above

The yields of small grains as a whole were lower than in
1922, but the yields of all cultivated crops were the highest on
record at the station. All crops grew to maturity without
suffering seriously for water at any stage of growth. There was
some damage by grasshoppers and plant diseases; particularly
rust on oats, rust and scab on wheat, and smut on corn were
abundant and reduced yields somewhat. Frost-free period, 150
days.

Crop year 1924
Precipitation :

Annual, 31 per cent above

Seasonal, 56 per cent below

Crop yields:

Winter wheat, 102 per cent above

Spring wheat, 27 per cent above

Oats, 24 per cent above

Corn, 16 per cent below

The soil was filled with water from the heavy rains of the
preceding fall. Low temperature and high humidity enabled
crops to utilize this water so economically that they produced
yields above the average in spite of a seasonal precipitation 56
per cent below the normal. At no time during the growth of
small grains was the soil wet by rain to a depth greater than
2 inches. Cultivated crops were helped materially by a rain of
1.41 inches on August 5. ' Frost-free period, 132 days.

RESULTS AT ABDMORE, S. DAK.

[Altitude, 3,549 feet; 12-year period (figs. 20 and 21)]

Climatic conditions: Mean annual precipitation, 16.69 inches;
mean seasonal precipitation, 10.84 inches; mean seasonal evapo-
ration, 36.919 inches.

Average frost-free period, 136 days.
Soil: Gumbo, decomposed Pierre shale.

Number of crop yields averaged each year: Winter wheat, 12;
spring wheat, 39; oats, 41; corn, 42.

Average annual crop 3'ields per acre: Winter wheat, 14.9
bushels; spring wheat, 17.4 bushels; oats, 32.8 bushels; corn, 15
bushels.

Crop year 1913
Precipitation :

Annual, 33 per cent below

Seasonal, 36 per cent below

Crop yields:

Winter wheat, 91 per cent below

Spring wheat, 88 per cent below

Oats, 93 per cent below

Corn, 100 per cent below

Conditions were fairly favorable until the middle of June,
when crops began to suffer from a lack of water. The rainfall

32

MISCELLANEOUS CIRCULAR 81. U. S. DEPARTMENT OF AGRICULTURE
ARDMORE (S. DAK.) FIELD STATION

YEAR

a

=

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

.MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1912

4

.63

1.68

.55

.27

T

.03

.40

.50

1.52

2.04

1.59

1.78

1 1.19

W. WHEAT

1.4

1913

3

S.WHEAT

2.0

2

OATS

2.3

I

—

CORN

0.0

1913

4

1.23

1.50

1.59

.15

.90

.02

.45

.28

3.27

1.24

3.24

.49

14.36

W.WHEAT

0.0

1914

3

S.WHEAT

0.0

2
1

OATS

0.0

1914

4

1.79

.75

1.51

1 i ■ i i_

T

I i . i i
.43

.50

.64

.86

4.26

3.40

6.67

I — Mi,

6.01

26.82

W.WHEAT

33.2

1915

3

S.WHEAT

46.8

?.

OATS

77.2

1

==»-=-

fc

■cziir~n ■~—?m« aUB _

CORN

38.8

1915

4

1.37

4-. 70

.81

.1 1

1.08

.25

.35

.54

1.04

3.61

2.58

1.80

18.24

W.WHEAT

31.3

1916

3

S.WHEAT

21.1

2

OATS

39.8

1

'».---

Kb ■

m

CORN

22.1

BB_ i. .

i.i • .i .

^jbJLi

■ -• — •-■ -'-

. i ..I i ._

. — v-^

joU

1916

4

1.90

.02

.85

.39

.20

.47

.09

1.02

2.74

5.34

1.71

.47

15.20

W.WHEAT

7.2

1917

3

S.WHEAT

9.2

2

OATS

15.2

1

. _ .

■

CORN

13.9

1917

4

1.99

.43

.67

.18

.70

.48

.29

.60

2.85

5.99 d 1.75

3.49

19.42

W.WHEAT

19.4

1918

3

S.WHEAT

35.0

2
1

OATS
CORN

65.1

— |-

■-«— =

1i~H -

1918

4

.44-

3.01

.45

.25

.66

T

.76

.93

IT rta in

2.52

2.65

1.50

3.05

16.22

W.WHEAT

18.3

1919

3

S.WHEAT

11.6

?.

OATS

22.4

■

I ■

1

H-

H ■ 1

CORN

9.2

_^^_n

B.i

., i.

' _ "W ' .

■ .,.,.,._

- _.B

_«_ ,1 - ■ , B mt . m

1919

4

.47

.38

2?10

.78

.14

.15

.73

.9 2

3.78

5.20

3.10

.77

18.52

W.WHEAT

25.7

1920

3

S.WHEAT

28.1

■

2

■

■

OATS

56.8

■

■

1

■

■ -*BH

■

CORN

19.3

..., „ _■ _«^

., -i i i . -

i.i i.i.

i .~H

_ KJB8! —

B J

.... ■ .

1920

4

1.59

.29

1.48

.29

.31

1.15

.18

.07

. .52

2.41

4.54

1.26

14.09

W.WHEAT

16.0

1921

3

S.WHEAT

1S.6

2

OATS

42.5

1

■

CORN

7.9

— — - ■...!«

i h ■■

^.1,1 i ■

. . , , i .

i i ■ .

■ OIL

1921

4

.55

.46

.66

.68

.30

.55

.14

T

3.23

2.56

2.59

4.07

15.79

W.WHEAT

0.0

•
1922

3

S.WHEAT

0.0

2

OATS

0.0

1

m j-

, , , ■

CORN

14.8

1922

4

.78

.15

.83

2.19

.41

.05

.30

.40

.98

3.80

5.93

.67

l 6.49

W.WHEAT

17.4

1923

3

S.WHEAT

24.4

2

OATS

59.1

1

1 i ZZ i~~

Sfi a ■

i ■ . .

_,., ,_,^_

_,_, ; ,.

— i ._ .

^Hh

CORN

29.5

1923

4

3.09

1.52

1.48

.13

.25

.02

.75

.70

.69

.75

1.95

2.61

13.94

W.WHEAT

9.3

1924

3

S.WHEAT

11.9

2

OATS

13.3

1

_ . _«o

CORN

2.4

AVERAGE

1.33

1.24

1.08

.45

.45

.31

.42

.57

2.28

3.25

3.10

2.21

16.69

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

' MAY

JUNE

JULY

TOTAL
YEAR

* Hail destroyed a/I
small grain in 1922

Fig. 20. — Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Ardmore (S. Dak.) Field Station

after June 1 came in small showers, and the total quantity was
inadequate to the needs of the crops, which practically failed
entirely except on fallow. Frost-free period, 141 days.

Crop year 1914

Precipitation:

innual, 16 per cent below

Seasonal, 24 per cent below

Crop yields:

VVLnter wheat, 100 per cent below.

Spring wheat, 100 per cent 1" Low.

Oats, 100 per cent below...

Corn, 100 per cent below

Small grains promised good yields until thej were destroyed
by hail on June 24. Com was injured by this and later hail-
storms and finallv Buffered from drought before it was out for

fodder without producing any grain. Frost-free period, 125
days.

Crop year 191

Precipitation:

Annual, 61 per cent above

Seasonal, 88 per cent above

Crop yields:

Winter wheat, 123 per cent above
Spring wheat, 169 percent above.

Oats, 135 per cent above

Corn, 159 per cent above

There was much lodging and some rust on the small grains.
Frost-free period, 136 da\ s.

Crop year 1916
Precipitation:

\i inual, 9 per cent above..

Seasonal, 17 per cent below

( Jrop j ields:

Winter wheat, 110 per cent above

Spring wheal, 21 per rent above

Oats, 21 percent above —

Corn, 47 per cent above

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

33

BUSHELS
INCHES

45

42

39

36

33

30

27

24

2 I

18

I 5

I 2

9

6

3

0-

(Arc/more, S. Dak. )

\

i i

\

1

/

\^>S. Wheat

/N.

-.---"1 7K

/

ZN

/
/

^ "^ Seasonal Evaporation N s

/
/

y\- — \y

\
\

/

/

s

V

\ :

/
/

\

\^ Oats

\
\

.

f\^

\
v

/

\^

fx N

1

^ 1 \\ h~W. Wheat

v — \ \= a, 1

S.WHEAT MEAN

OATS MEAN

W.WH EAT MEAN

,,,/v — ,. — , — — . .

//rvt

X 1

1 \\ | \ 4 i

j //i\. X i

— — _l

\|\"~ £f~-

ill
ill

<§V

■f\

^~~~~**-~\'v

ill
///

V\

Seasonal Ra/nfall

\\

yi\ ~**~<

^^oi>\^

A_

'18 '20 '16 '23 '19 '22 '17 '14 'Z\ *24

Fig. 21. — Diagram summarizing the relations between rainfall and crop yields at Ardmore, S. Dak.

The soil was well filled with water in the spring from the
heavy precipitation of the preceding fall. Small grains ex-
perienced no lack of water until about the middle of July. After
this time there was some shortage, but conditions were not
severe or long continued. Winter wheat and barley yielded
relatively much more than spring wheat and oats, because they
were earlier. Corn went through the season under favorable
conditions except that its maturity was hastened by hot, dry,
windy weather. Frost-free period, 121 days.

Crop year 1917
Precipitation :

Annual, 9 per cent below

Seasonal, 5 per cent below

Crop yields:

Winter wheat, 52 per cent below

Spring wheat, 47 per cent below

Oats, 54 per cent below

Corn, 7 per cent below

Much of the precipitation in May and August was lost by
run-off. Crops suffered from a cold late spring, drought, exces-
sively high temperatures in late July and early August, and two
hailstorms. Frost-free period, 150 days.

Crop year 1918

Precipitation :

Annual, 16 per cent above

Seasonal, 30 per cent above

Crop yields:

Winter wheat, 30 per cent above

Spring wheat, 101 per cent above

Oats, 98 per cent above

Corn, 48 per cent above

This was next to the wettest year in the history of the station
and a year of heavy production. Frost-free period, 129 days.

Crop year 1919

Precipitation :

Annual, 3 per cent below

Seasonal, 10 per cent below

Crop yields:

Winter wheat, 23 per cent above

Spring wheat, 33 per cent below

Oats, 32 per cent below

Corn, 39 per cent below

Small grains suffered for water at intervals in both May and
June and before harvest in July. Winter wheat profited by its
earliness and yielded above the average. Corn suffered from
drought in the latter part of the season. Frost-free period, 130
davs.

Crop year 1920
Precipitation :

Annual, 11 per cent above

Seasonal, 19 per cent above

Crop yields:

Winter wheat, 73 per cent above

Spring wheat, 62 per cent above

• Oats, 73 per cent above

Corn, 29 per cent above

The rainfall after June 20 was deficient, but the soil was
well filled with water, and there was little suffering from a lack
of it. Frost-free period, 149 days.

11810°— 27-

34

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
SCOTTSBLUFF (NEBR.) FIELD STATION

YEAR

I

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1911

i

0.65

2.14

1.10

0.08

0.34

0.20

0.60

1.27

3.72

1.66

1.61

2.45

15 82

W. WHEAT
" S.WHEAT- "

13 3
~1 7.6" "

1912

I

|

1

1

|

OATS

34.4

-. — hr^=

1912

4

1 ■■!■ ■ I

2.77

2.70

SUn —
1.16

0.37

. . ■■ .
0.02

1 m ' ■ ■ ■

0.08

0.46

11^— M

0.85

— mHti — m
0.13

3.72

1.71

1.30

15.27

W.WHEAT

10.0

1913

3

S.WHEAT

1 1.6

2

OATS

25.0

1 |

i B ,., _

m

CORN

30.1

1913

4

— 4.33

1.18

0.47

0.1 1

1.07

0.00

0.04

0.19

3.18

2.29

1.84

0.39

15.09

W.WHEAT

21.9

1914

3

S.WHEAT

10.7

2

OATS

17.3

R -

1

1914

4

m — k — SB
0.54

i.n n.

0.24

0.88

■ ^-' ' '
0.00

0.36

0.15

0.7 1

2.12

4.27

2.37

1.94

2 20

15.78

W.WHEAT

24.4

1915

3

1

S.WHEAT

,8,,_i

1

■

2

■

OATS

52.6

■L

1

-— ■

=zML

1 S"

CORN

12.9

1915

4

4.62

3.65

0.90

0.05

0.60

0.19

0.16

0.09

0.53

2.21

2.14

1.87

17.01

W.WHEAT
S.WHEAT

5.7
I 8.2

1916

9

2

■

■

a

OATS

10.4

P -]

■

■

■

■

■-HB&

idHlr

.. Pfc i

■ .

aL

iM-rr

— m4

CORN

' 29.1

1916

4

2.24

0.48

1.00

0.19

0.27

0.14

0.06

0.98

2.03

5.20

2.09

0.62

15.30

W.WHEAT

6.9

1917

3

S.WHEAT

15.6

2

OATS

24.2

1

==—«■■ ■

-

CORN

26.8

1917

4 i 0.37

1.65

0.37

0.09

0.14

0.34

0.27

0.28

3.61

4.26

1.23

1.02

13.63

W.WHEAT

0.0

1918

3

S.WHEAT

11.4

-

2

■

OATS

25.8

B

■

■ ■

1

1-

, ,., , _M m.tL.

JLJ — iv

^

CORN

16.2

1918

4

1.27

3.47

0.69

0.32

1.42

0.05

0.45

0.43

0.54

1.45

1.04

I.S7

12.50

W.WHEAT

4.5

1919

3

S.WHEAT

1 2.3 ,

2

OATS

CORN

2.8

5.6

K

1

■

I ■■ ■

JtL__L_

ItatK

*■ _.

mo , , i

■ . -

■fea

*m ■ ■ ■

— ■ ■

1919

4

0.09

3.23

1.30

0.70

0.15

0.29

0.41

0.67

2.05

4.13

2.09

3.27

18.44

W.WHEAT

8.7

1920

3

S.WHEAT

17.6

2

■

■

OATS

36.5 j

b5_

■

1

M

... . «.

m-kr

■E

-fcJh-

-M-l-B

CORN

26.6

1920

4

1.80

0.57

1.16

0.09

0.33

0.76

0.10

0.14

0.57

3.31

1.37

1.55

11.75

W.WHEAT

10.3

1921

3

S.WHEAT

5.8

2

OATS

12.S

1

ta ■=

CORN

8.2

AVEBA

3E

1.87

1.94

0.90

0.20

0.47

0.22

0.33

0.70

2.06

3.06

1.71

1.60

15.06

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fig. 22.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Scottsbluff (Nebr.) Field Station

Crop year 1921

Precipitation:

Annual, 16 per cent below

Seasonal, 19 per cent below

Crop yields:

Winter wheat, 7 per cent above

Spring wheat, 7 per cent above

Oats, 30 per cent above

Corn, 47 per cent below

The precipitation was particularly deficient in April and
from about June 20 to the end of the growing season. Corn
began suffering from drought about July 10, and the condition
was not relieved. Small grains suffered from a lack of water
during the latter part of their growing season. Frost-free
period, 137 days.

Crop year 1922
Precipitation:

Annual, 5 per cent below

Seasonal, 15 per cent above

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, 100 per cent below

Oats, 100 per cent below

Corn, 1 per cent below

Exccptionallv promising crops of small grains were completely
destroyed bv hail on July 1. Corn was about 3 feet high and
was badly damaged, but there was plenty of water available, and
recovery was much more rapid and complete than appeared
possible. The vield would have been much higher if the crop
Dad not been damaged by the hail. Frost-free period, 135 days.

Crop year 1923

Precipitation:

Annual, 1 per cent below

Seasonal, 5 per cent above

Crop yields:

Winter wheat, 17 per cent above

Spring wheat, 40 per cent above

Oats, SO per cent above

Corn, 97 per cent above --

July was very dry. Small grains suffered for water during
that month. Conditions were favorable for corn throughout
the season and the second highest yield in the history of the
station was obtained. Frost-free period, 157 days.

Crop year 193.',

Precipitation:

Annual, 16 per cent below.

Seasonal, 45 per cent below

Crop yields:

Winter wheat. 3S per cent below

Spring wheat, 32 per cent below

Oats, 59 per cent below

Corn, 84 per cent below

Soil moisture conditions were very unsatisfactory in the
spring. The rainfall was not sufficient for the needs of the
small grains, and by the last of June they were l^eyond the
possibility of recovery to make a good crop. Corn was beyond
recovery by the end of July. It continued to suffer and finally
dried up with practically no grain on it in any of the fields.
The yields of small grains were remarkably good, considering
the character of the season. Frost-free period, 128 days.

CHOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

35

BUSHELS
INCHES

(Scottsb/uff, Nebr.)

42

39

36

33

30

27

24

2 1

18

15

12

9

6

3

0-

-

^ ^ Seasonal Ei/aporat/on

^-

s.

/

\<

s'

* ■—*—*«. ^

+***

N

/

*

•>.,

s
s

N

----.^

N^'

jr / ■ ■

CROP YIELDS

Oats

/

i

^-5. W/>ecry- y

\

\ y^W. Wheat

j/\/

/

\

j7*

VVi^^^/

V ^

■ OATS MEAN i-
S. WHEA T MEAN "
W. WHEAT MEAN

~^*«/VV

^

.---^~

^-^

\^^ZL^^j^ \

Vel^S

^Seasonal Ftainfa// \

\

«.<"

1920

'16 '12 '15 .'17 '13 '14 '18 '19

Fig. 23. — Diagram summarizing the relations between rainfall and crop yields at Scottsbluff, Nebr.

RESULTS AT SCOTTSBLUFF, NEBR.

[Altitude, 3,900 feet; 10-year period (figs. 22 and 23)] ,

Climatic conditions: Mean annual precipitation, 15.06 inches;
mean seasonal precipitation, 8.43 inches; mean seasonal evapora-
tion, 37.391 inches.

Average frost-free period, 130 days.

Soil: Brule clay, above the ditch level on irrigated farm.

Number of crop yields averaged each year: Winter wheat,
11; spring wheat, 27; oats, 37; corn, 36.

Average annual crop yields per acre: Winter wheat, 10.6
bushels; spring wheat, 11.8 bushels; oats, 24.1 bushels; corn,
20.7 bushels.

Crop year 1912
Precipitation :

Annual, 5 per cent above

Seasonal, 11 per cent above

Crop yields:

Winter wheat, 27 per cent above

Spring wheat, 45 per cent above

Oats, 43 per cent above

Corn, 88 per cent above

Winter precipitation was good, and the soil was in fine con-
dition at seeding time. There was some winterkilling of winter
wheat. Frost-free period, 125 days.

Crop year 1913

Precipitation :

Annual, 1 per cent above

Seasonal, 19 per cent below

Crop yields:

Winter wheat, 6 per cent below

Spring wheat, 2 per cent below

Oats, 4 per cent above

Corn, 46 per cent above

Crops began to suffer from drought about June 20, and the
rain that fell thereafter until the small grains were harvested

was inadequate to their needs. Later rains enabled corn to
make a good yield. Winter wheat suffered from winterkilling
as well as from drought. Frost-free period, 140 days.

Crop year 1914

Precipitation:

Annual, mean.

Seasonal, 9 per cent below

Crop yields:

Winter wheat, 107 per cent above..

Spring wheat, 9 per cent below

Oats, 28 per cent below

Corn, 51 per cent below

Conditions for crop growth were favorable until June 22.
There was little precipitation to benefit crops after that date,
and the spring grains and corn ripened prematurely or dried up.
Spring grains were heading about the time conditions became
unfavorable, but winter wheat was farther advanced and pro-
duced a good crop. Frost-free period, 129 days.

Crop year 1915

Precipitation:

Annual, 5 per cent above

Seasonal, 27 per cent above

Crop yields:

Winter wheat, 130 per cent above..

Spring wheat, 53 per cent above

Oats, 118 per cent above

Corn, 38 per cent below

The stand of winter wheat was poor, as a result of the dry
fall and winter. Precipitation during the growing season was
abundant. A hail storm on August 7 reduced the average
yield of spring wheat, which was only partly harvested, and
destroyed the prospects for a fair yield of corn. Other grains
were harvested before the hail and were but little injured by it.
Frost-free period, 113 days.

36

MISCELLANEOUS CIBCULAB

NOR-TH PLATTf

81, U. S. DEPARTMENT OF AGRICULTURE
: (NEBRj FIELD STATION

YEAR

a

AUG.

SEPT.

OCT.

NOV.

\
DEC

JAN.

FEB.

MARCH APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1906

J

S.56

4.25

3 05 | 1.01

0 96

0 39

0 51

0.10 1 0 23

2 61

2 53

4 74

25 94

BARLEY

37 7

1907

3

S.WHEAT

24 7

1_
1

OATS

31.4

— wJi

CORN

20.2

1907

4

1.80

2 44

0 64

0.31

0 80

0 16

0.78 1 0.20

0 45

4.59

6.01

3 44

1' 62

1 BARLEY

35 5

1908

3

f S.WHEAT

26 6

2

! OATS

61.1

1

■ _ II.. , , Mm

: — — —

b~h

Wl M ifcj ^ftflfll M immm

CORN

26 1

1908

4

1.88

0.20

3.41 _

0 59

0.20

0 29

1.61

0.99

0.55

3 09 | ■ 4 99

_ 5. 48

13 27

1 BARLEY

19.1

1909

3

2

!

., B ,

mm [

,_

f CORN

r 26.4

4

1.73 | 0.46

0 22

2 24

1.37

0.34

0.02 •

0.19

0.62

1.76

3.1 1

0 12

12 13l | BARLEY

15 2

1910

3

[_ S.WHEAT

8 2

1909

2

r oats

13.1

■

1

JLzs

±s

m-

-m

CORN

5.3

1910

4

3.21

0.97

0 01

0.1 1

0.72

0 28

0.39

0 20

2 34

1 34

0 50

3.61

13 68

BARLEY

0 0

1911

3

| S.WHEAT

0 0

2

1

^OATS

0 0

I CORN

0.6

H M 1

> ... i

_

— — —

. ._■_

. n ,

. _

1911

4

2 64

1.26

3 45

0.04

0.65

0.74

0.81

3.08

3.02 1 1.72

0.70

2.78

20 89

[_ W.WHEAT 1 9.7

1912

3

L S.WHEAT

6 4

2

OATS

1 13 7

1 g

— w Bfiitf ~ i '

-■.. . -«~~" "i^fc

| CORN

27 2

1912

4

1.33

2.04

1.44

0.01

0.18

0.16

0 94

1.68

2.09

2.44

2.81

2.76

1783

W WHEAT

14 4

1913

3

| S.WHEAT

3 3

2

1 OATS

0 0

1

I m — i~~

J_

B . —

.,,,,,

_ , . ^

-.. M.a

VL

. M HiJPmBb ■

~M~m7m

1 CORN

0 0

1913

4

1.28

099

0.14

0.14

3 09

0.18

0 96

0.41

1.46

1.66

4.59

1.37

16 27

W.WHEAT

7 3

1914

3

S.WHEAT

5 9

a

2

■

1 OATS

9 8

H

1

i

7~! — .1

CORN

5 3

■--»-

..■

B K

.1.. ... ..

■

. . . . ■

.. , mim ■ -

1914

4

3.54

0.16

1.39

T.

0.87

0 51

1.1 1

2.23

6.77 ■

5 80 1 4 76

6i9 ■> .; . :

W.WHEAT

35 5

1915

3

S.WHEAT

27 2

2

OATS

69 3

!

; .

[Jg m

, ^ , ,

-■-■> -

g M _„

CORN | 28 2

1915

4

3.19

2.09

1.16

0.22

0.82

0.85

0.81

0 20

0.70

2.23

4.40

0.40

17 07

1 W.WHEAT

30.9

1916

3

£ S.WHEAT

18 2

2

1 OATS

37.4

1

=rr~'

_^_ r_m

CORN

7.2

1916

4

2.68

1.40

0.50

0.47

0.42

0.74

0 35

1.48

1.45

4.02

2.00

0.78

16 49

W.WHEAT

0 0

1917

3

S.WHEAT

6 7

2

■

CATS

3 5

1

- a-JJJJll m _

-=

CORN

7.3

1917

4

3.46

2 45

0.39

0.71

0 27

0.54

0.28

0.32

2.32

3.26

1.82

1.93

17.75

W.WHEAT J

7 9

1918

3

S.WHEAT

S 2

2

OATS

9.1

1

—

—

CORN

21 2

1916

4

1 98

0.46

1.43

0.29

1.31

0 03

1.50

0.44

1.77

2.72 1 BJ 7.33

5.33

2459

W.WHEAT

21.8

1919

3

S.WHEAT

15.1

2

OATS

36 4

1

CORN

34 1

1919

4

1.12

1.81

1.36

2.83

0.32

0.07

0.72

0 38

4.24

3.49

1 93 | 3 31

21 58

W.WHEAT

28 3 j

1920

3

S.WHEAT

17.3

2

OATS

42 8

1 9

M

=— — -

—

CORN

33 9

1920

4

4.52

0.15

1 29

0 04

0 60

0.68

0 36

0.42

1.17

2.43

1.14 1 3.12

15 92

W.WHEAT

23 6

1921

3

S.WHEAT

9.7

2

OATS
CORN

J8.1
15 5

1

■o .!

• 1.™-"

— B-

^^ ]

nzs

m! m

1921

4

3.50

1 56

0 92

0 04

0.14

0.66

0.05

0.47

2.88

4.19 | 1.17 | 4.69

20 27

W.WHEAT

13 0

1922

3

S.WHEAT

4 3

2

■

OATS
CORN

14 0
28 4

91 BJ

1

;JJ

-T--

-r-rrrrr

- — |

mI , _

L nL ^k

1922

4

2.35

0 66

0.14

2 35

0.01

0.11

0.14

0 38

2.02

6.17

4 63

5.52

24 48

,•, WHEAT

\ 5 1

1923

3

S.WHEAT

19 6

2

OATS

60 6

1 I — IS

imJL

CORN

47 3

1923

4

3 B0

1 40

1 77

0 45

0 39

0 08

0 36

1 93

0 36

2 48

2 35

1.81

17 18

W WHEAT

37 3

1924

3

S.WHEAT

16 4

2
1

PJ

__mm "

CORN

22 8

AVERAGE

2.77

1 37

1 26

0 66

073

0 38

065

0 84

1 91

3 11

3 15

3 19

2002

MONTH

AUG.

SEPT

OCT

NOV

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fio. 24.— Relations between annual crop yields and precipitation, by five-day, monthly, and < rop-J eat periods, at the North Piattt (Nebr I Field Station

CROP YIELDS AND PRECIPITATION IN THE GEEAT PLAINS AKEA

37

(North Piaffe, Nebr.)

36
33
30

27

24

21

I 8

15

12

9

6

3

0

July

□

ATlflM

— June

\\\ L^ir i

A 1 IUiN

May

./£//.

=Z=\-

ANNUAL MEAN

Apr.

— — 4\

UUNE

1 ___- ^

S^7

— _L— — L— —

1

/ /

w

.^" ~~~~~~~J_____

/n

\u-f—

rr CROP YEAR
GROWING SEASON

WINTER
FALL

Mar.

/ /

MAY

1/

/

X.

--^4^=

^r^T^k^li

/

A,^^-^!

^--'-"

XI 1 - f~ DEC.-UAr,

* — »^^_

-"-

<<p=±

Nov.

i

V

---""

1 """""i"'

1 ^ ^

*s 1 •

■**^j_-—

AUG. -SEPT. -OCT -NOV.

1 j 1 1

1915 '07 '19 '23 '09 '08 '20 '12 '22 '13 '18 '24- '16 '17 '14 '21 'II '10

Fig. 25. — Diagram summarizing the relations between rainfall and crop yields at North Platte, Nebr. (See text, p. 38)

Crop year 1916

Precipitation:

Annual, 13 per cent above

Seasonal, 20 per cent below

Crop yields:

Winter wheat, 46 per cent below

Spring wheat, 30 per cent below

Oats, 57 per cent below

Corn, 41 per cent above

The heavy precipitation in the fall of 1915 made the precipi-
tation for the crop year above the average. Conditions were
unfavorable to all crops except corn. There was some winter-
killing in winter wheat, and all small grains suffered from drought,
high winds, and soil blowing in the spring. There were three
damaging hailstorms on June 1, 2, and 12. The last was par-
ticularly severe and practically destroyed the small grains.
Frost-free period, 122 days.

Crop year 1917

Precipitation :

Annual, 2 per cent above

Seasonal, 18 per cent above

Crop yields:

Winter wheat, 35 per cent below

Spring wheat, 32 per cent above

Oats, mean.

Corn, 30 per cent above

Two-thirds of the winter wheat was destroyed by winter-
killing and soil blowing. The spring was very wet, but the
summer after June 5 was exceptionally dry, and all small
grains suffered seriously from drought. Spring w_heat with-
stood the conditions better than the other small grains. Corn
suffered some from grasshoppers as well as drought. Frost-free
period, 150 days.

Crop year 1918

Precipitation :

Annual, 9 per cent below

Seasonal, 20 per cent above

Crop yields:

Winter wheat, 100 per cent below

Spring wheat, 3 per cent below

Oats, 7 per cent above

Corn, 12 per cent below

The season was comparatively unfavorable to crop production.
Due to unfavorable conditions in the fall, no stand of winter
wheat was secured. About the middle of July small grains
began to show the effects of drought. A few days of hot wind
came at this critical time and ripened the grain prematurely.
Corn suffered from the drought in July and August. All crops
were damaged some by grasshoppers. Frost-free period, 128
days.

38

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1919

Precipitation:

Annual, 17 per cent below

Seasonal, 48 per cent below

Crop yields:

Winter wheat, 58 per cent below

Spring wheat, 81 per cent below

Oats, 88 per cent below

Corn, 73 per cent below

The season was the most disastrous to crops in the history of
the station. The precipitation was scant, and there were periods
of extreme heat and hot winds. Frost-free period, 111 days.

Crop year 1920

Precipitation :

Annual, 22 per cent above

Seasonal, 37 per cent above

Crop yields:

Winter wheat, 18 per cent below

Spring wheat, 49 per cent above

Oats, 51 per cent above

Corn, 29 per cent above

Winter wheat suffered from soil blowing in March.
free period, 142 days.

Crop year 1921

Precipitation :

Annual, 22 per cent below

Seasonal, 19 per cent below

Crop yields:

Winter wheat, 3 per cent below

Spring wheat, 51 per cent below

Oats, 48 per cent below

Corn, 60 per cent below

Frost-

The chief source of damage was dry weather in June and
July. Frost-free period, 140 days.

RESULTS AT NORTH PLATTE, NEBR.

[Altitude, 2,821 feet; 18-year period (figs. 24 and 25)]

Climatic conditions: Mean annual precipitation, 20.02 inches;
mean seasonal precipitation, 11.36 inches; mean seasonal evapo-
ration, 41.955 inches.

Average frost-free period, 154 days.

Soil: Loess on high plateau 100 feet above valley of Platte
River; very deep and uniform.

Number of crop yields averaged each year: Winter wheat, 25;
spring wheat, 19; oats, 23; barley, 5; corn, 22.

Ayerage annual crop yields per acre: Barley, 21.5 bushels;
winter wheat, 18.8 bushels; spring wheat, 12.9 bushels; oats,
28.3 bushels; corn, 19.8 bushels.

Crop year 1907

Precipitation:

Annual, 30 per cent above

Seasonal, 11 per cent below

Crop yields:

Barley, 75 per cent above

Spring wheat, 91 per cent above

Oats, 11 per cent above

Corn, 2 per cent above

The spring opened early but was cold and dry. The drought
continued until May 20, and the last freeze was May 26. The
stand and vitality of spring-sown small grains suffered, oats
being affected more than wheat. Oats also suffered material
loss from smut. Corn was not planted until after the spring
drought, but it suffered more or less from the droughl begin-
ning the last of July and continuing through August. Frost-
free period, 139 days.

Crop year 190S
Precipitation:

Annual, S per cent above

Seasonal, 28 per cent above

Crop yields:

Barley, 65 per cent above

Spring wheat, 106 per cent above

Oats, 116 per (cut above...

Corn, 32 per cent above

The dry spring retarded the growth of straw, and later rains
encouraged the filling of the train. Corn suffered quite severely
from late drought. Frost-free period', 151 days.

Crop year 1909

Precipitation:

Annual, 16 per cent above

Seasonal, 24 per cent above

Crop yields:

Barley, 11 per cent below

Spring wheat, 33 per cent above,. _

Oats, mean.

Corn, 33 per cent above

Crops did not suffer materially from a lack of water during
the season, but stands were seriously reduced by late spring
freezes and high winds. Wheat was injured less than barley
and oats. Frost-free period, 164 days.

Crop year 1910

Precipitation :

Annual, 39 per cent below

Seasonal, 51 per cent below

Crop yields:

Barley, 30 per cent below

Spring wheat, 36 per cent below

Oats, 54 per cent below

Corn, 73 per cent below

The stand and vitality of small grains suffered from freezes in
the last half of April, but the primary cause of the low yields in
1910 was drought. Both the crop year and the season were the
driest in the history of the station. Frost-free period. 156 days.

Crop year 1911

Precipitation:

Annual, 32 per cent below

Seasonal, 31 per cent below

Crop yields:

Barley, 100 per cent below

Spring wheat, 100 per cent below

Oats, 100 per cent below

Corn. 97 per cent below

This was the second driest year in the history of the station.
Probably some grain would have been produced on fallow if it
had not been destroyed by grasshoppers. Frost-free period, 155

lays.

Crop year 191 J

Precipitation:

Annual, 4 per cent above

Seasonal, 2S per cent below

Crop yields:

Winter wheat, 49 per cent below

Spring wheat, 50 per cent below

Oats, 52 per cent below

Corn, 37 per cent above

Small grains began to show drought damage about the 25th
of May and suffered serious damage from hot winds the lasl
three days of that month. The light rains from June 5 to 13
only slightly relieved the situation, but they saved the crops
from total failure. The rains of July and the first half of August
made the corn crop. Frost-free period, 157 days.

Crop year 1913
Precipitation:

Annual, 11 per cent below

Seasonal, 11 per cent below

Crop yields:

Winter wheat, 23 per cent below

Spring wheat, 71 per cent below

Oats, 100 per cent below

Corn, 100 per cent below..

The fir-t seeding of oats failed to make a stand on account of
-prine freezes, and it was necessar\ to reseed, which made the
oafs late. They were badly fired by the middle of June and were
eaten up by grasshoppers by July 9. Spring wheat made a

Hood growth of straw but did not fill, on account of hot winds
and the lack of water. Winter wheat had a heavy growth of
^traw by the fore part of June, but hot weather and a lack of
water resulted iii a very poor fill. Grasshoppers began eating

the corn in the latter part of June and continued until all pro-
perl < of a crop were none before the middle of August. They
were assisted in t he destruction by a hailstorm on July 15. Frost-

free period, 15 1 daj s.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

39

Crop year 1914

Precipitation :

Annual, 19 per cent below

Seasonal, 20 per cent below

Crop yields:

Winter wheat, 61 per cent below

Spring wheat, 54 per cent below

Oats, 65 per cent below

Corn, 73 per cent below

Small grains made a fair to good growth of straw, but the lack
of rain after June 21 and grasshopper injury resulted in very
poor yields of grain. Corn was suffering badly from drought
and grasshoppers by July 10. Grasshoppers continued towork
throughout the month until the leaves were gone. Rains in the
latter part of August were too late to be of much help. Frost-
free period, 149 days.

Crop year 1915

Precipitation :

Annual, 66 per cent above

Seasonal, 107 per cent above

Crop yields:

Winter wheat, 89 per cent above _.

Spring wheat, 111 per cent above _

Oats, 145 per cent above

Corn, 42 per cent above

This was the wettest year since records began in 1875, with the
greater part of the excess occurring during the growing season.
Yields were very heavy. Winter wheat suffered some loss by
lodging, with rust and scab in the lodged spots. Corn suffered
some damage by grasshoppers and a hailstorm and was not
fully mature when frosted. Frost-free period, 138 days.

Crop year 1916

Precipitation :

Annual, 15 per cent below

Seasonal, 32 per cent below

Crop yields:

Winter wheat, 64 per cent above

Spring wheat, 41 per cent above

Oats, 32 per cent above

Corn, 62 per cent below

The soil was filled with water from the heavy rains of the
previous year. Small grains suffered some from hot, dry
weather in the later stages of growth. Winter wheat was so far
advanced when dry weather set in that it was little damaged.
By the time the drought ended on August 11 much of the corn
was beyond recovery. Frost-free period, 169 days.

Crop year 191'i

Precipitation :

Annual, 18 per cent below

Seasonal, 27 per cent below

Crop 3'ields:

Winter wheat, 100 per cent below.

Spring wheat, 48 per cent below.

Oats, 70 per cent below

Corn, 63 per cent below

The limiting factor in crop production was water. No rain
of any consequence fell from June 5 until after the small grains
were harvested. Corn revived somewhat after the rains begin-
ning August 19, but much of it was beyond recovery. Winter
wheat failed to survive the winter. Frost-free period, 157 days.

Crop year 1918

Precipitation :

Annual, 11 per cent below

Seasonal, 18 per cent below

Crop yields:

Winter wheat, 58 per cent below

Spring wheat, 60 per cent below

Oats, 68 per cent below

Corn, 7 per cent above

June was the severe month of the growing season. High tem-
peratures and a deficient water supply combined to bring about
a critical condition. Small grains came into head, but filling of
the grain was very imperfect, ripening was premature, and yields
were very low. Corn was not seriously injured at this time.
Later rains were sufficient for its needs. Frost-free period, 133
days.

Crop year 1919

Precipitation:

Annual, 23 per cent above

Seasonal, 51 per cent above

Crop yields:

Winter wheat, 16 per cent above..
Spring wheat, 17 per cent above...

Oats, 36 per cent above

Corn, 72 per cent above

Small grains, particularly oats and winter wheat, suffered
considerable loss from rust. Frost-free period, 161 days.

Crop year 1920

Precipitation:

Annual, 8 per cent above

Seasonal, 14 per cent above

Crop yields:

Winter wheat, 51 per cent above

Spring wheat, 34 per cent above

Oats, 51 per cent above .

Corn, 69 per cent above

The quantity and the distribution of the precipitation was
such that crops did not suffer acutely for lack of water at any
time. Frost-free period, 152 days.

Crop year 1921

Precipitation:

Annual, 20 per cent below

Seasonal, 31 per cent below

Crop yields:

Winter wheat, 26 per cent above

Spring wheat, 25 per cent below

Oats, 36 per cent below

Corn, 22 per cent below

Early prospects for small grains were good, but a shortage
of water in June caused rapid deterioration and premature
ripening. Winter wheat, being farther advanced, suffered less
than other crops. The yield of corn was reduced by dry weather,
but the quality was unusually good. Frost-free period, 155 days.

Crop year 1922

Precipitation:

Annual, 1 per cent above

Seasonal, 14 per cent above

Crop yields:

Winter wheat, 31 per cent below

Spring wheat, 67 per cent below

Oats, 50 per cent below

Corn, 43 per cent above

Small grains presented an unusually fine appearance the first
week in June, but continued dry weather during that month
resulted in a rapid decline, an early harvest, and very low yields.
The distribution of the precipitation was quite favorable for
corn. The yield of that crop was above the average, and its
quality was good. Frost-free period, 172 days.

Crop year 1928
Precipitation:

Annual, 22 per cent, above

Seasonal, 62 per cent above

Crop yields:

Winter wheat, 20 per cent below

Spring wheat, 52 per cent above

Oats, 114 per cent above

Corn, 139 per cent above

The crop had an abundance of water. The average yield of
winter wheat was low, owing to the fact that winter survival
was poor except on fallow. Frost-free period, 157 days.

Crop year 1924
Precipitation :

Annual, 14 per cent below. .

Seasonal, 38 per cent below.
Crop yields:

Winter wheat, 98 per cent above-
Spring wheat, 27 per cent above-
Oats, 93 per cent above

Corn, 15 per cent above

The season was characterized by deficiencies in precipita-
tion, temperature, and evaporation. The soil was well filled
with water; the distribution of the rainfall was very favorable,
especially to small grains, while low temperatures during the
drier periods did much to prevent serious drought injury. Frost-
free period, 161 days.

40

MISCELLANEOUS CIRCULAR 61. U. S. DEPARTMENT OF AGRICULTURE
ARCHER .WVO.; FIELD STATION

YEAR| 5

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

_MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

cropI

YEAR I

19)3

4

2 09

2 23

0.66

0.46

1.65

T.

0.60

0.56

2.54

1.46

11 2

1.43

14 80

S .WHEAT
W.WHEAT

7.0
5.6

1914

3

2

OATS

1 6.5

1

■ Bfl.n i

■

■ ,._

CORN

140

1914

4

2.03

0.32

1.29

0.26

0.16

0 08

0.49

0.71

4.90

1.78

1.83

165

15.50

S. WHEAT

24.8

1915

3

W.WHEAT

26 0

2

OATS

39.6

1915

4

2.53

1.95

1.81

0.03

0.56

0.10

0.09

0.19

0.74

1.61

l_ -IB .
0.48

1.81

11.90

S .WHEAT

0 3
4.0

1916

3

W.WHEAT

5.2

2

OATS

6.5

■

1

■ 1"

-t-Itt-

i .B

CORN

19.9

1916

4

4.05

1.37

0.73

0.88

0.34

0.06

0.80

0.85

1.87

4.54

0.46

1.79

17.74

S .WHEAT

14 8

1917

2

W.WHEAT

14.0

2

OATS

28.8

1

^-—

CORN

21.1

1917

4

1.20

0.91

0.57

0.40

0.81

0.47

0.89

0.19

4.14

1.86

2.78

2.74

1696

S. WHEAT

233

1918

3

W.WHEAT

14.5

■

B

2

■

■

OATS

32.8

6

■

'

■ _..— -

■

. B. ;

l.ftjL.

f9lk —

CORN

30.2

1918

4

1.66

2.41

1.33

0.54

0.58

T.

0.14

0.87

0.58

0.31

0.59

2.76

11.77

S. WHEAT

3.8

1919

3

W.WHEAT

1.4

2

l

OATS

1.3

1

J |ff ■ M

CORN "W

60

1919

4

1.19

3.10

1.48

1.26

1.10

0.20

0.69

0.34

3.88

2.08

4.33

1.21

20.86

S .WHEAT

3.5

1920

3

W.WHEAT

46

■

2

■

■ _

OATS

13.6

■

■ 1

1

=-

-kLt.

rifely

lJJ^=

CORN

48

1920

4

1.25

o.ea

«0.57

0.15

0.27

0.95

0.07

0.14

0.86

2.19

2.47

1.79

11.59

S .WHEAT

ICO

1921

3

W.WHEAT

18.1

2

OATS

CORN

12.4

12 2

1

■

n ■ I ■

B_.M<a

r ml 1 ■ ■

• — • •

. _ —

■ ••■ ■

•■ . . i i

iii i • »—

!■■ —

■ ■__■ m _■ ,.—

1921

4

0.76

0.08

- 0.21

0.08

0.73

0.32

0.28

0.20

2.33

2.15

2.30

1.81

11 25

S. WHEAT

3-7

1922

3

W.WHEAT
OATS

24
1.7

2

1

-■ . . ■

- ■ —

., . _ ,

■ _ _■_ ■■ tM B aV — I

CORN

15.1

1922

4

2.36

0.14

0.06

2.23

0.44

0.06

0.42

1.06

0.86

2.98

2.69

1.38

14.68

S. WHEAT | 13.6

1923

3

W.WHEAT

10.2

2

OATS

16.2

1

CORN

356

1923

4

4.59

1.14

3.32

0.16

0.09

0.06

0.30

0.87

0.58

3.38

0.86

0.50

15 85

S. WHEAT

10.5

1924

3

W.WHEAT

17.0

2

OATS

17.3

1

CORN

16.1

AVERA

GE

2.16

1.32

1.09

0.59

0.61

0.21

0.43

0.54

2.12

2S.X

1.81

1.72

14 81

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN."

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fig. 26. — Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Archer (Wyo.) Field Station

RESULTS AT ARCHER, WYO.

[Altitude, 1,481 feet; 11-year period (figs. 26 and 27)]

Climatic conditions: Mean annual precipitation, 14. SI inches;
mean seasonal precipitation, 7.86 inches; mean seasonal evapora-
tion, 36.897 inches.

Average frost-free period, 138 days.

Soil: Clay loam "hard land."

Number of crop yields averaged each year: Spring wheat, 30;
winter wheat, 13; oats, 34; corn, 37.

Average annual crop yields per acre: Spring wheat, 10. S
bushels; winter wheat, 10. S bushels; oats, 17 bushels; corn, 15.9
bushels.

Crop year 1014
Precipitation:

\nnual, mean.

Seasonal, 17 per cent below

Crop yields:

Spring wheat, 35 per cent below

Winter wheat, 48 per eenl below

Oats, 3 per cent below

Corn, 12 per cent below

All crops were damaged by hail on June 1 I. Small grains
suffered from drought which followed the hailstorm and was
not broken until July 26. Corn yields were reduced l>\ drought
m \ugust. Frost-free period, 130 days.

Crop year 1015

Precipitation:

Annual, 5 per cent above

Seasonal, 29 per cent above

Crop yields:

Spring wheat, 130 per cent above

Winter wheat, ill percent aboi

Oats, 133 per cent above

Corn, 100 per cent

below

The cool season and an ample supply of water at all limes
favored the growth of small grains. Yields were probably
reduced a Little by ruM . The season was too cool for corn,
which had only reached the roasting-ear stage when frosted on
October 3. Frost -free period, 111 days.

Crop year 1016
Precipitation:

Annual, 20 per cent below

Seasonal, 41 percent below

Crop 3 ields:

Spring wheat. ('>.'! percent below

Winter wheat. 52 per eent below

Oats, 69 per cent below

Corn, 25 per cent ab< ive

Drought was the cause of the low yields of small grains. All

plats reached the heading stage, but many did not fill. Winter

CEOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

41

(Archer, Wi/o)

1920 '17 "18 '24 '15 '14 '23 '16 *I9 '21 ' Z2

Fig. 27. — Diagram summarizing the relations between rainfall and crop yields at Archer, Wyo.

wheat suffered from soil blowing in the latter part of March.

The rainfall of late July and the month of August enabled corn

to make a crop 25 per cent above the average. Frost-free period,

134 days.

Crop year 1917

Precipitation :

Annual, 20 per cent above

Seasonal, 10 per cent above

Crop yields:

Spring wheat, 37 per cent above

Winter wheat, 30 per cent above

Oats, 69 per cent above

Corn, 33 per cent above

Winter wheat was injured by soil blowing and on plats under
most methods was killed when the temperature went down to
4° F. on April 30. It was reseeded to spring wheat. The season
was unusually late, and all crops made a slow growth until the
latter part of June. The water supply was sufficient for their
needs. Frost-free period, 154 days.

Crop year 1918
Precipitation :

Annual, 15 per cent above

Seasonal, 47 per cent above

Crop yields:

Spring wheat, 116 per cent above

Winter wheat, 34 per cent above

Oats, 93 per cent above

Corn, 90 per cent above 1 ,

The water supply was sufficient for the needs of the crops at
all times, and yields were among the highest recorded at the
station. Frost-free period, 167 days.

Crop year 1919

Precipitation :

Annual, 21 per cent below

Seasonal, 46 per cent below

Crop yields:

Spring wheat, 65 per cent below

Winter wheat, 92 percent below

Oats, 92 per cent below

Corn, 62 per cent below

The small precipitation before July 1 made conditions very
unfavorable to crops. In addition to the drought damage,
winter wheat winterkilled on most of the plats and was reseeded
to spring wheat. Spring wheat was injured by rust. Oats and
corn especially were damaged by hail on August 7. Corn was
very soft. Frost-free period, 123 days.

Crop year 1920

Precipitation :

Annual, 41 per cent above

Seasonal, 46 per cent above

Crop yields:

Spring wheat, 68 per cent below

Winter wheat, 57 per cent below

Oats, 20 per cent below

Corn, 70 per cent below

The spring was very cold and wet, and the growth of crops
was further delayed by heavy hail storms in June. Seeding was
delayed pending administrative action as to the continuation of
the work. Frost-free period, 137 days.

42

MISCELLANEOUS CIRCULAR 81, U. S. DEPAKTMEXT OF AGRICULTURE
AKRON (OOL-O.) FIELD STATION

YEAR

2

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1908

4

1.47

0.05

3 20

2 00

T.

T.

1.38

3.06

0 4 0

1 87

3.32

4.61

21 36

W. WHEAT
S.WHEAT

14.1
1 3 8 "

1909

3

2

OATS

CORN

19.4
24.9

E_

1

,,,,,.

~ ; H — i

J

1909

4

3.77

2.12

0.86

0.48

0.55

0.05

0.16

0.26

3.96

2.06

1.38

1.47

17.12

W.WHEAT

14.1

1910

3

S.WHEAT

9.2

2

OATS

13.3

1

~BB»— 9Kk~ ■" TT-1

m . _

— B — B» ifcJI B , ~a~

CORN

10.9

1910

4

3.72

3.81

0.05

0.12

0.32

0.60

0.44

0 C6

2.63

1.15

1.48

1.34

15 72

W.WHEAT

4.1

1911

3

S.WHEAT

3.7

2

OATS

4.0

1

CORN

3.2

1911

4

1.30

2.40

1.47

0.28

1.36

0.28

1.43

0.78

2.49

2.86

3.39

3.58

21 62

W.WHEAT

33.8

1912

3

S.WHEAT

19.7

2

OATS

42.3

■

1

i

3

I a E

CORN

30.9

*Aa i l l_l l C

1 ■-. ,

— tit

1 .

. i .

.as. BBS

1912

4

1.58

1.88

1.99

0.18

0.29

0.22

0.40

1.57

2.19

1.44

1.35

1.85

14.94

W.WHEAT

7.4

1913

3

S.WHEAT

3.9

2

I OATS

6.6

1

| g a

CORN

3.9

1913

4

1.14

2.08

0.34

0.70

3.27

0.03

0.32

0.20

4.01

1.45

3.54

1.66

18.75

W.WHEAT

25.5

1914

3

■

tra

S.WHEAT

1 6.6

■

2

■

■

■

OATS

42.2

H _

■

1

■

■

irgpj n

w m

m B

CORN

1 1.3

-H_ 1-

_■ mM. .

m , , , BH . . ,

in i ■

.,., ■ I

1914

4

1.05 | 0.23

2.08

0.10

0.90

1.10

; 58

1.50

5-19 g

4.13

3.75

1.10

22.81

W.WHEAT

21.8

1915

3

I

S.WHEAT J 27.3

■i.

OATS

64.3

1

^.jKfc,

CORN

29.2

1915

4

3.51

1.76

0.48

0.15

0.65

0.5C

T.

0.09

1.59

2 24

2.09

1.77

1483

W.WHEAT

13.7

1916

3

S.WHEAT

7.1

2

OATS

11.3

1

pj^

■ , i '

—

k~_r-~~

,,,,.,

i==sJ

CORN

1.1

1916

4

2.82

0.26

1.02

0.75

0.61

0.28

0.63

0.72

0.96

7.79

0.56

1.52

17.92

W.WHEAT

6.6

1917

3

S.WHEAT
OATS

13.2
26.2

2

1

&*ftJ

A

R ■■■

CORN

15.2

1917

4

1.78

2.19

0.57

T.

0.50

0.70

0.80

0.60

1.20 1

1.76

0.96

3.10

14.16

W.WHEAT

5.3

1918

3

S.WHEAT

1.1

2

OATS

1.4

1

j3I

CORN

12.4

1918

4

■587.36

2.43

1.07

0.75

1.55

0.07

0.50

0.65

1.9S

1.59

2.27

1.79

21.99

W.WHEAT
S.WHEAT

15.0
6.3

1919

3

2

1

OATS

16.9

tB rri- ■ ■ ■ .1 . , , ■

CORN

4.S

1919

4

044

2.62

1.64

1.29

•^0.70

0.00

0.02

0.90

3.28

2.90

3.97

4.72

2248

W.WHEAT
S.WHEAT

14.2
18. 7~

1920

|

1

?

OATS

44.2

1

-m

■ . U

CORN

35.6

1920

4

1.45

1.80

0.44

0.47

0.90

1.22 1 T.

1.25

2.77

0.47

1.32

2.88

14.97

W.WHEAT
S.WHEAT

12.3
2.1

1921

3

1
1 1

— n

2
1

t

, K

=1=

Lj

^

L :

■ . . ■■

CORN

6.3

1921

4

3
?

0.92

0.79

0 97

0.20

0.65

0.65

0.25

0.15

3.96

3.63

1.43

3.24

1684

W.WHEAT
S.WHEAT
OATS

0.6

6.9

15 9

1922

1922

1

4
3
?

1.24

B. - :

0.06

0.05

i ■■ l_

1.90

■ i i ... I
0.10

-....■
T.

0.18

0.95

1.65

4.94

2.17

3.62

16 86

CORN
W.WHEAT
S.WHEAT
OATS

1 1.2
2.9
4.6

14.4

1923

1923

1
4

3

—1 i III

0.75

I . ..i . ■
0.82

«j i

1.91

0.47

— 1J~.\ I. —
0.70

-j i_l LL.

0 50

" " 1 — L.

0.59

1.25

0.31

3.26 I 0.35

1.71

12 62

CORN
W.WHEAT
" S.WHE^f

17.9
3.9
0S~

1924

2
1

■ ,

i f-

n , . ■_

— L. VT

i"-^-

■ • — Jl m , , ,

-Krr

CORN

1.8

AVERAGE

2 14

1.58

1.13

0.62

0.82

0.39

055

0.87

2.41

2.72

2.08

2.50

1781

MONTH

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fic. 28.— Relations between annual crop yields and precipitation, by flvc-day, monthly, and crop-year periods, at the Akron (Colo.) Field Station

CKOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

43

[Akron, Colo.)

1915 '20 '19 '12 '09 "14- '17 '10 '23 '22 'ii '21 '13 '16 '18 '24-

(Fig. 29.— Diagram summarizing the relations between rainfall and crop yields at Akron, Colo. (See text, p. 44)

Crop year 1921

Precipitation :

Annual, 22 per cent below

Seasonal, 7 per cent below

Crop yields:

Spring wheat, 7 per cent below

Winter wheat, 68 per cent above_

Oats, 27 per cent below

Corn, 23 per cent below

Small grains began to suffer from drought about July 10.
Winter wheat suffered less than spring wheat, because it was
farther advanced. Corn was affected later by the drought.
Frost-free period, 139 days.

Crop year 1922

Precipitation :

Annual, 24 per cent below

Seasonal, 9 per cent above

Crop yields:

Spring wheat, 66 per cent below

Winter wheat, 78 per cent below

Oats, 90 per cent below

Corn, 5 per cent below

The fall and winter of 1921-22 were unusually dry, the pre-
cipitation for the eight months from August to March, inclusive,
being less than 3 inches. There being no reserve water in the
soil, crops were extremely sensitive to droughty conditions under
a seasonal precipitation only 9 per cent above the normal.
There was no stand of winter wheat in the spring, and plats were
reseeded to spring wheat. Corn survived the drought much
better than the small grains. Frost-free period, 128 days.

Crop year 1923

Precipitation:

Annual, 1 per cent below

Seasonal, 1 per cent above

Crop yields:

Spring wheat, 26 per cent above —

Winter wheat, 6 per cent below

Oats, 5 per cent below

Corn, 124 per cent above

Much of the winter wheat was killed by soil blowing in the
winter. Spring seeding was late. The yields of wheat and oats
were reduced by rust, and oats were damaged by hail as they were
ripening. Conditions were very favorable to corn, the late rains
causing a heavy production of grain. Frost-free period, 149
days.

Crop year 1924

Precipitation :

Annual, 7 per cent above [—

Seasonal, 32 per cent below

Crop yields:

Spring wheat, 3 per cent below

Winter wheat, 57 per cent above

Oats, 2 per cent above

Corn, 1 per cent above

The season of 1924 was marked by a severe drought during
June, July, and August. The relatively good yield of winter
wheat was due to the heavy precipitation in the fall of 1923 and
in May, 1924. Corn and spring-sown small grains were able to
make about average yields. Frost-free period, 146 days.

44

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

RESULTS AT AKRON, COLO.

[Altitude, 4,669 feet; 16-year period (figs. 28 and 29)]

Climatic conditions: Mean annual precipitation, 17.S1 inches;
mean seasonal precipitation, 9.71 inches; mean seasonal evapora-
tion, 43.116 inches.

Average frost-free period, 139 days.

Soil: Clay loam, "hard land."

Number of crop yields averaged each year: Winter wheat, 17;
spring wheat, 23; oats, 31; corn, 27.

Average annual crop yields per acre: Winter wheat, 12.2
bushels; spring wheat, 9.7 bushels; oats, 21.3 bushels; corn,
13.8 bushels.

Crop year 1909

Precipitation:

Annual, 20 per cent above

Seasonal, 5 per cent above

Crop yields:

Winter wheat, 1G per cent above

Spring wheat, 42 per cent above

Oats, 9 per cent below

Corn, 80 per cent above

No stand was obtained with winter wheat, and it was reseeded
to spring wheat.. The season was generally favorable. Some
damage was done by hailstorms on June 9 and July 7. Frost-
free period, 140 days.

Crop year 1910

Precipitation:

Annual, 8 per cent below

Seasonal, 9 per cent below

Crop yields:

Winter wheat, 16 per cent above

Spring wheat, 5 per cent below

Oats, 38 per cent below

Corn, 21 per cent below

Crops suffered from the drought that extended from June 5
to July 29. Small grains began to suffer about June 12 and
corn about July 4. Later rains enabled the corn that set to
mature, but small grains were all harvested by July 18. Frost-
free period, 132 days.

Crop year 1911

Precipitation:

Annual, 12 per cent below

Seasonal, 32 per cent below

Crop yields:

Winter wheat, 66 per cent below

Spring wheat, 62 per cent below

Oats, 81 per cent below

Corn, 12 per cent below

Small grains made a slow growth in April and May, and
during June they suffered acutely from drought. Corn made
a good growth in June, but was severely injured by drought in
July. Frost-free period, 150 days.

Crop year 1912
Precipitation:

Annual, 22 per cent above

Seasonal, 27 per cent above

Crop yields:

Winter wheat, 117 per cent

above.
Spring wheat, 103 per cent
above.

Oats, 99 per cent above

Corn, 124 per cent above

Small grains suffered very little from drought or damage
from any cause. Corn tired Bome in September and was not
fullv mature when frosted on September 20. Frost-frcc period,
130' days.

Crop year 1913
Precipitation:

Annual, 16 per cent below

Seasonal, 30 per cent below

Crop yields:

Winter wheat, 39 per cent below

Spring wheat, 60 per cenl below..

Oats, 69 per cent below

Corn, 72 percent below

The spring was very cold and late, with a sudden change in
temperature and the beginning of a prolonged drought about
the middle of May. Winter wheat began to suffer from drought
in May, and all small grains were firing badly by the middle of
June. Corn began to suffer the first week in July. Frost-free
period, 139 days.

Crop year 1914
Precipitation:

Annual, 5 per cent above

Seasonal, 10 per cent above

Crop yields:

Winter wheat, 109 per cent above

Spring wheat, 71 per cent above

Oats, 98 per cent above

Corn, 18 per cent below

All small grains made good yields, although they suffered
from drought for nearly two weeks before they were harvested
about the middle of July. Corn suffered more seriously from
the drought at this time and again in the latter part of August.
Frost-free period, 124 days.

Crop year 1915
Precipitation:

Annual, 28 per cent above -.
Seasonal, 46 per cent above _
Crop yields:

Winter wheat, 79 per cent

above

Spring wheat, 181 per cent

above

Oats, 202 per cent above

Corn, 112 per cent above

Winter wheat suffered some loss by winterkilling. Small-
grain harvest was about three weeks later than usual. The
maturity of corn was also late. Frost-free period, 137 days.

Crop year 1916

Precipitation:

Annual, 17 per cent below

Seasonal, 21 per cent below

Crop yields:

Winter wheat, 12 per cent above

Spring wheat, 27 per cent below

Oats, 47 per cent below

Corn, 93 per cent below

Precipitation was deficient but was supplemented to some
extent by water stored in the soil from the excess of the previous
season. Winter wheat made short straw but filled well and was
the only crop to yield above the average. Spring-sown small
grains on plats under most methods did not grow tall enough
to harvest with a binder. Corn began to suffer from drought
early in July and on many methods did not tassel. Frost-free
period, 121 days.

Crop year 191?
Precipitation:

Annual, 1 per cent above

Seasonal, 12 per cent above

Crop yields:

Winter wheat, 46 per cent below

Spring wheat, 36 per cent above

Oats, 23 per cent above

Corn, 9 per cent above _. -..

The stand of winter wheat in 1917 was seriously reduced by
drought, low temperatures, and soil blowing in March and
April. Wheat and oats suffered from drought, and some plats
did not fill well. Much of the corn was soft. Frost-free period.
149 days.

Crop year 1918
Precipitation:

\nnual, 20 per cent below

Seasonal, 2S per cent below

Crop yields:

Winter wheat, 57 per cent below

Spring wheat, S9 per cent below

Oats, 95 per cenl below

Corn, ID per cent below

Small grains burned badly, winter wheat early in June and
spring grains during the latter pari of the month. Winter

w beat ripened the firsl of July, and spring grains dried up about
a week later, straw was too shorl to bind except on fallow,
and on many plats it was too short and thin to harvest at all.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

45

Corn burned badly the first of July, but rains later in the month
saved a part of it, and the heavy precipitation of August sup-
plied water to mature a crop only 10 per cent below the average.
Frost-free period, 165 days.

Crop year 1919
Precipitation:

Annual, 23 per cent above

Seasonal, 22 per cent below

Crop yields:

Winter wheat, 23 per cent above

Spring wheat, 35 per cent below

Oats, 21 per cent below

Corn, 67 per cent below

Small grains began to suffer from drought the middle of
June. Straw was short, and some of the spring-sown grain
did not head out. Winter wheat being farther advanced suffered
less and was the only crop to yield above its average. Corn
began to suffer from drought in July, and on many plats it did
not tassel. Frost-free period, 122 days.

Crop year 1920
Precipitation :

Annual, 26 per cent above

Seasonal, 53 per cent above

Crop yields:

Winter wheat, 16 per cent above

Spring wheat, 93 per cent above...

Oats, 108 per cent above

Corn, 158 per cent above

Ample rainfall nicely distributed made 1920 one of the best
crop years in the agricultural history of the region. Frost-free
period, 136 days.

Crop year 1921

Precipitation :

Annual, 16 per cent below

Seasonal, 23 per cent below

Crop yields:

Winter wheat, 1 per cent above .

Spring wheat, 78 per cent below

Oats, 38 per cent below

Corn, 54 per cent below

Small grains began to suffer from drought early in June.
Winter wheat being farther advanced than spring-sown small
grains was able to mature a better crop. The yield of winter
wheat on fallow was especially good. Corn began to suffer
early in July, but the heavy rain of July 22 came in time to
allow it to make a partial yield of grain. Frost-free period,
151 days.

Crop year 1922

Precipitation :

Annual, 5 per cent below

Seasonal, 26 per cent above

Crop yields:

Winter wheat, 95 per cent below

Spring wheat, 29 per cent below

Oats, 25 per cent below

Corn, 19 per cent below .

Winter wheat did not survive the dry fall, winter, and spring.
Small grains began to suffer about the middle of June from
deficient precipitation. The continued dry weather with high
temperatures in the first of July caused them to head short,
ripen rapidly, and yield poorly. Conditions favored corn until
the latter part of August, when a lack of water reduced its
prospective yield. Frost-free period, 160 days.

Crop year 1923

Precipitation :

Annual, 5 per cent below

Seasonal, 28 per cent above

Crop yields:

Winter wheat, 76 per cent below

Spring wheat, 53 per cent below

Oats, 42 per cent below

Corn, 29 per cent above

Winter wheat did not germinate in the fall and in the spring
made a poor stand of plants of low vitality. The yields of
spring wheat and oats were cut down by wind, drought, and
high temperatures in the latter part of June and the first of

July. The light August rainfall seriously cut down the pros-
pective yield of corn. Frost-free period, 136 days.

Crop year 1924

Precipitation :

Annual, 29 per cent below |

Seasonal, 42 per cent below

Crop yields:

Winter wheat, 68 per cent below

Spring wheat, 95 per cent below

Oats, 73 per cent below

Corn, 87 per cent below

With the crop-year precipitation 29 per cent below and the
seasonal precipitation 42 per cent below the normal, all crops
nearly or quite failed. Frost-free period, 130 days.

RESULTS AT COLBY, KANS.
[Altitude, 3,138 feet; 11-year period (rigs. 30 and 31)]

Climatic conditions: Mean annual precipitation, 20.29 inches;
mean seasonal precipitation, 11.11 inches; mean seasonal evapo-
tion, 39.819 inches.

Average frost-free period, 155 days.

Soil: Clay loam (Colby silt loam).

Number of crop yields averaged each year: Winter wheat, 41;
barley, 6; milo, 35; corn, 15.

Average annual crop yields per acre: Winter wheat, 19.2
bushels; barley, 22.6 bushels; milo, 16.5 bushels; corn, 20.9
bushels.

Crop year 1914
Precipitation :

Annual, 3 per cent above

Seasonal, 5 per cent above

Crop yields:

Winter wheat, 42 per cent below

Barley (none sown).

Milo (no yields).

Corn, 96 per cent below

When the Colby station was established the experimental field
had been seeded to winter wheat. This was allowed to remain
on all small-grain plats. The wheat on the plats to be planted
to corn and other cultivated crops was about 6 inches high when
plowed or listed up. . The crops that followed suffered from a lack
of the water which the wheat had used and produced very little
or no grain. The season was very favorable to winter wheat in
the section, but the yields on the station plats were below the
average for the locality. Frost-free period, 161 days.

Crop year 1915

Precipitation:

Annual, 27 per cent above

Seasonal, 69 per cent above

Crop yields:

Winter wheat, 31 per cent above. _.

Barley, 115 per cent above

Milo, 90 per cent below

Corn, 137 per cent above

There was some lodging and poor filling of winter wheat,
evidenced by a light weight per bushel. The season being wet
and cool was unusually favorable to spring-sown small grains,
but too cool for corn, and much of it was soft when frost came.
May and June were so cold and wet that it was impossible to
secure good stands of milo, and only the earliest heads were
mature when frosted on October 5. Frost-free period, 137 days.

Crop year 1916

Precipitation :

Annual, 19 per cent below

Seasonal, 23 per cent below

Crop yields:

Winter wheat, 15 per cent above

Barley, 59 per cent below

Milo, 100 per cent below

Corn, 97 per cent below

The water stored in the soil from the rains of 1915 and the
distribution of the precipitation during the early part of the
season were favorable to the production of a good crop of winter
wheat of high quality. Dry weather in early spring and a heavy

46

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

COL_BV (KANS.

) FIELD STATION

YEAR

a

AUG.

SEPT.

OCT.

NOV.

DEC

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1913

t

0.62

2 69

0.29

0.56

436

005

0 45

0.21

1.21

3.07

2 32 || 5.01

20.84

W WHEAT
BARLEY

112

1914

3

■

I

■

■

2

■

■ B

MILO

--

■

■ H

1

IlLi

i^sziih^i.—

^ i M

■4— I^B.

CORN

08

1914

4

1.85

0.52

0.87

T.

0.S1

0.38

1.49

1.43

3.61

4.55

4.03

6.60

25.84

W. WHEAT

25.1

1915

3

BARLEY

48.S

2

MILO

1.7

1

.■ , .

._ , E

-j^ _,

CORN

49.6

1915

4

4.17

0.67

1.10

0.48

0.48

0.55

0.05

0.33

2.03

1.33

3.15

2.07

16.41

W.WHEAT

22.0

1916

3

BARLEY

92

2

■

MILO

00

9

1

Am

mt f mm

^

■ _

B — "* ■

■

CORN

06

K |

a ■ -

_ H— ,.

■ m.

■ — M_

1916

4

1.48

0.40

0.62

0.21

0.37

0.12

0.20

0.56

1.66

1.99

1.42

3.07

12.10

W.WHEAT

00

1917

3

BARLEY

00

2

MILO

25

1

, „_

szrrrH

^_Jj

__jihI

CORN

1.2

1917

4

5.78

4.25

0.28

0.42

0.20

0.7 7

1.79

1.34

1.05

2.16

0.19

1.86

20.09

W.WHEAT

17.0

1918

3

■

BARLEY

5.8

■

2

m m

■

MILO

6.1

I

■

>■

■ -■-

1 In

1

■H

CORN

1.1

ma , i .

.m . , _

_.. , ■_ ,.i , nf m ._.

,.m i.l , , _.i

HL.

1918

4

1.88

2.16

2.87

0.21

Z.63

T.

1.57

0.59

2.80

2.23

2.47

395

23.36

W.WHEAT

" "barley ~

30.1
44 3

1919

3

2
1

■

MILO
CORN

31.4
25.6

J:

— I"

|

1919

4

0.65

^2.07

0.62

1.63

0.19

0.23

0.31

0.46

3.74

2.42

5.68

4.19

I

22.39

W.WHEAT

31.5

1920

3

BARLEY

28.5

2

MILO

26.4

1

a ■

■

M 1 ft|_ |

CORN

52.4

I , , , ,

1 i 1

H_ .

■ , .H

■iai ti

m\ !■ I i ■■

... i •■ ■

1920

4

3.75

2 56

2.71

0.27

1.31

1.15

0.03

0.58

1.88

1.85

3.52

4.24

23.85

W WHEAT

23.9

1921

3

BARLEY

17.1

2

■ B

MILO

23.6

■ ■

■

■

^ - mm

• E

-mmrl =

— =-*-

Trr*

■ , , ,

Jbn

ILi 1

CORN

23.4

1921

4

2 23

2.80

0.45

0 18

0 46

0.1 8

0.35

1.26

4.06

2.55

1.34

2.74

18.62

W.WHEAT

22.5

1922

3

BARLEY

19.2

2

■

MILO
CORN

20.3
21.2

■

1

Bm^ —

«1^

, . . ■

■~TT"I

rTTm

s-mrr-

i^J^i

1922

4

1.38

0.43

0.08

3.13

0.02

0.05

0.18

0 88

2.80

6.28

3.27

3.46

21.S6

W.WHEAT

5.5

1923

3

BARLEY

35.6

■

2

■

MILO

43.5

■

L

■

CORN

45.9

_

...... m mi , ,

< i

.,.,..

.i. i ■ i •.

-. HtaM .

a^H^»

1923

4

355

1.87

3.33

0.12

0.75

0.22

1.82

1.67

0.46

1.30

0.80

1.77

17.58

W.WHEAT

22.3

1924

3

BARLEY

18.1

2

MILO

9.3

■

1

JL — ■

— ■■ \m» ^i.

■

— ri-m-

■■ —

-7tA\^

"- 1

CORN

8.4

AVERAGE

2.48

1.86

1.22

0.66

1 03

0.34

0.75

0.85

2.30

2.70

2.56

3.54

20.29

MONTH
____

AUG.

SEPT

OCT.

NOV

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fir,.' 30.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Colby (Kans.) Field Station

weed growth made conditions unfavorable to spring-sown small
grains. Dry hot weather in July and August prevented corn
from earing. Poor stands of sorghums were obtained. Their
growth was stunted by a dry hot summer, and a rather early
frost prevented their maturity. Frost-free period, 135 days.

Crop year 1917

Precipitation :

Annual, 40 per cent below

Seasonal, 27 per cent below

Crop yields:

Winter wheat, 100 per cent below..

barley, 100 per cent below

Milo, 85 per cent below

Corn, 94 per cent below

Small grains were total failures. Little winter wheal survived
the dry fall, winter, and spring. That which did was injured by
hail on June 5. The failure of spring-sown small grains was due
to a dry soil to start with, a lack of sufficient seasonal precipita-
tion, and damage by hail and hot winds. Corn was seriously
injured by drought in the latter part of June and during July.
The August rainfall came too late. The crop was Injured by
hail on June 5 and again early in August. Grain sorghums were
delayed in growth up to the fir-t of AugUffl by hot dry weather
and 'hot winds. They were Bet back by the bail in early August

and were frosted when only a small part of the seed was mature.
Frost-free period, 153 days.

Crop year 1918

Precipitation:

Annual, 1 per cent below

Seasonal, 53 per cent below

Crop yields:

Winter wheat, 11 per cent below

Barley, 74 per cent below

Milo, 63 per cent below

Corn, 95 per cent below

Winter wheat suffered severely from drought the latter part
of May. A heavy rain on May .'><) saved the crop, but it was
again materially damaged by hot winds and dry weather during
the latter part of June. Spring-sown small grains were first
injured by a hard northwest wind on May 9 which caused some
soil blowing and was followed by a freeze. They Buffered like
the winter wheat from drought and hot winds. Corn did well
until it tasseled, but hoi dry weather in August prevented it
from earing well. Grasshoppers contributed to the injury.
The first planting of milo was washed out or covered up by
the dashing rain of May 30, and June plantings failed to dome
Up on account of the hot dry weather. The limited stand thai
was obtained produced fairly well, although its yield was kept
down by dry weather. Frost-free period. 169 davs.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

47

BUSHELS
INCHES

54
5 I
48
45
42
39
36
33
30
27
24
2 I
18
I 5
I 2

9

6

3

(Co/6y, Kons\

y

j\.

f* D

\

CO/77 /

v_ n^i i 1 1_ l-\s j

M

"\, Seasono/ Evaporation

•^ Bar/eu^ 1

^ /

• V •---.>

---"

\\

""

N

V

/
/

A'

-'$

/

/V
-/ — \-N

4 — -V

\

\ ■

/

'./

\

t-4

T K

\

\ \

k — ■ -\i

o

\

\

W. Wheat ^

_. . . \\& . .

\

\

X

BARLEY MEAN

CORN MEAN

W. WHEAT

1 \

::. ■"■^?l .— — ■■

~~ - ■%

r V

..' ' i \_ ' V- -

/

1 \

\

\

\
\

\

**** *

s

/

\

\

\

* 1

\

k'

v \

\

\

"** Seasonal Rainfall \

s ■

\

\

fyf

v~^~

i

\^r

\\

1

■

N......-4

1915

'21 '19 '20 '23 '1* '18 '22 '24 '16 '17

Fig. 31. — Diagram summarizing the relations between rainfall and crop yields at Colby, Kans. (See text, p. 45)

Crop year 1919

Precipitation :

Annual, 15 per cent above

Seasonal, 3 per cent above

Crop yields:

Winter wheat, 57 per cent above...

Barley, 96 per cent above

Milo, 90 per cent above

Corn, 22 per cent above

Conditions were very critical for winter wheat in the latter
part of May and for corn in the first part of July, but rains
came in time to relieve the situation. Hot winds and dry
weather in the latter part of June checked the filling of spring-
sown small grains and reduced the prospective yields. Barley
being farther advanced suffered less loss than spring wheat and
oats. Winter wheat was too far advanced to be seriously
affected. Corn suffered some from drought before the rains in
August and was materially injured by hot wind in August.
Conditions were decidedly favorable for milo. Frost-free period,
168 davs.

Crop year 1920
Precipitation:

Annual, 10 per cent above

Seasonal, 44 per cent above

Crop yields:

Winter wheat, 64 per cent above _

Barley, 26 per cent above

Milo, 60 per cent above

Corn, 151 per cent above

In general the season was free from hot winds, periods of
drought, and insect pests. Winter wheat and barley suffered
a little from a lack of water for a short period preceding the

middle of June. Milo was injured to some extent by heavy
freezes in late September. Frost-free period, 153 days.

Crop year 1921

Precipitation:

Annual, 18 per cent above

Seasonal, 3 per cent above

Crop yields:

Winter wheat, 24 per cent above

Barley, 24 per cent below

Milo, 43 per cent above

Corn, 12 per cent above

The stand of oats and barley was thinned by a temperature
of 8° F. on the 9th of April. Conditions were generally favor-
able. Winter wheat that had made the heaviest growth suffered
some from a lack of water in May. Frost-free period, 164 days.

Crop year 1922

Precipitation:

Annual, 8 per cent below.

Seasonal, 4 per cent below

Crop yields:

Winter wheat, 17 per cent above

Barley, 15 per cent below

Milo, 23 per cent above

Corn, 1 per cent above

Winter wheat came through the winter in very weak condition.
Ripening was hastened by dry weather in June. Barley was
affected to some extent by the same dry period. The yield
and quality of corn was lowered by hot, dry weather in August.
Milo suffered from dry weather in August and September.
Frost-free period, 162 days.

48

MISCELLANEOUS CIRCTJLAB 81, U. S. DEPARTMENT OF AGRICULTURE
HAYS (KANS.) FIELD STATION

YEAR

;

AUG. SEPT.

OCT. NOV

DEC

JAN

FEB.

MARCH

APRIL

^MAY

JUNE JULY

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1906

4

2.87

3.39

2.94

o.se

0.51

0.64

0.22

0.65

0.1 1

0.80

4.72

^^9

27.00

W.WHEAT

11.7

1907

3

i

■ -

BARLEY

6o~

2

■ ■

I 1

KAFIR

21 .5

■ 1 1 _ ■

n ■

■ H

1

-t-U-rJ-J-H-

__ i — ^

^ —

■ ... . H

JJUs

AjL

C 0 R '.■

6.1

1907

.;

2.65 | 2.06 1 1 .06

0.1 I

1 .76

7

0.92

T

2.18

2.93

6.05

2.82

22.79

W.WHEAT

,10.6

1908

3

in 1 1

,

_

BARLEY

11.7

2

J

■

KAFIR

0.0

1 H

■

1

H L

.. ■...,

^J-

CORN

6.3

1908

4

S.29 | 0.74

1 .76

1.79

0.03

039

0.28

1 .16

039

1 .28

■JO. 04

3.66

26.61

W.WHEAT

0.0

3

■

BARLEY

00

■

2

■

KAFIR

13.3

1909

1

+J^T^

_M t . t — —

, _ , J

, — , ,

i . . , , ' m

7HS*~

CORN

15.0

1909

4

1.37

2.90

1 .78

3 55

1 .00

0.58

0.26

0.03

0 97

3.88

2.58

2.02

20.92

W.WHEAT

32.5

1910

3

BARLEY

24.3

2

KAFIR

i 73

' S ■ B

B _ ,

, | , L — m-

W7T,

_

, , i., i

|— ««-7 — M^fc

CORN

7.1

1910

4

4,01

0.80

0.3 2

T

0.14

0.12

2.1 2

0.14

0.78

2.10

0.85

2.66

14.04

W.WHEAT I

13

1911

3

BARLEY

0.2

2

KAFIR

1.5 J

1

... . ■

—

CORN

0.0 ^

1911

4

3.44

2.56

0.30

0.14

1.82

0.02

1 98

1.60

1.66

3.40

3.49

0.55

20.95

W.WHEAT

145

1912

3

BARLEY

26.3

^

1

KAFIR

22.7

■

E

^^ —

CORN

2.6

1912

4

3.9 6

1.59

0.56

1.1 3

0.03

0.36

0.68

0.41

2.97 BP5.72

3.34

0.55

21.30

W.WHEAT

7.1 j

1913

3

BARLEY

7.1

2

KAFIR

00

_Bfap_t»

| -

-a ;

— _i-_

__.

CORN

o.o 1

1913

4

0.11

4.64

0.24

0.72

3.1 1 *

0.04

0.42

0.15

2.24

*336

3.13

1.51

19.67

W.WHEAT

20.8

1914

3

BARLEY

15.1

■

2

■

KAFIR

S.I

■

1

m Hi

— . 1 J : 1

CORN

3.3

1914

4

3.01

0.53

1 .17

T

0.63

0.68

1.80

1.74

3.84 [s.96| | 5.04

6.13

30.53

W.WHEAT

17.2

1915

3

BARLEY
KAFIR

35.7
503

2

1 |—

g | _

_ M

m

CORN

176

1915

4TT 3.91

2.88

0.58

0.30

0.04

0.53

0.15

0.31

2.60 1 1.49

5.87 1 0.40

19.06

W.WHEAT

33.2

1916

3

BARLEY

14.7,

2

KAFIR

6.3

< ■

■ ■ .

CORN

2j1

1916

4

2.03

1.15

1.04

0.02

0.61

0.11

T

0.07

2.07

1.65

2.15 | 1.07

11.97

W.WHEAT

5.6

1917

3

BARLEY

1.3

2

KAFK

1.3

1

_ m

CORN

1.2

1917

4

5.56

1.54

0.09

1.64

0.15

0.80

1.15

1.71

2.81 1 4.86

0.60 | 3.24

24.15

W.WHEAT

143

1918

3

1

BARLEY

18.1

2

KAFIR

2.2

■

1

J

N_**c .lb B . . . _■

T*br8

CORN

14

1918

4

1 ,81

1.35

2.31

1.1 0

2.36

T

2.1 8

0.33

6.01» 1 5.89

2.83

1.34

26.53

W.WHEAT

'5 7

1919

3

BARLEY

387

2

B

KAFIR

276

1

^

B_

=t

CORN

40

1919

4

0.8S

3.28

1.85

1.54

0.15

0.05

0.37

0.30

2.25

3.68

1.93

2.27

18.52

W.WHEAT

31.3

1920

3

BARLEY

34.5

■

2

— m

KAFIR

3&2

M

■

1

■ ■_.^

—±m

4^—

■ ~: a

■ ■ ■ ■ ■

CORN

165

i . i •»

-.-jJ.B.B. _M M-m

— ^^B ■

1920

,T5e3

1 .37

3.58

0.73

0.46

0.40

0.10

0.49

339

2.64

3.76

3.28

26.03

W.WHEAT

3t6

1921

1

I 1_

KAFIR

38.3

1921

4

3.46

a- a

0.63

0.05

0.00

0.50

T

0.93

1.71

4.96

3.24 | 3.56 | 2.48

21.52

W.WHEAT

276

1922

3

J

BARLEY

352

2

I

b=B^i

KAFIR
CORN

I7.S

6 5

1922

4

0.59

0.28

0.27

1.28

T

T

0.10

1.04

1.61

4.29 1 4.44

0.64

14.44

W.WHEAT

00

1923

3

BARLEY

IM

KAFIR

171

1

KM—

■ ......

CORN

0.0

1923

4

4.02

■'■ • ■

4.37

0 ?9

C 37

0.31

0.26

1.81

0.92

3.26 1 0.47

1.97

22.38

W.WHEAT

41 7

1924

BARLEY

372

2

■

KAFIR
CORN

26.4
7.1

AVERA

GE

3.04

2.01

1.35

.84

.76

L..

.28

.77

.77

2.28

. . .,._■

336

3.60

2.53

21.59

MONTH

AUG.

SEPT

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

TOTAL
YEAR

Fig. 32,— Relations between annual crop yields and precipitation, by Dve-day, monthly, and crop-year periods, at the Hays (Kans.) Field Station.

CEOP YIELDS AND PRECIPITATION IN THE GEEAT PLAINS AEEA

49

(Hays, Kans.)

1915 '07 '09 '19 '21 '18 '08 '24- '22 '13 '12 '10 '14 '16 '20 '23 'II

Fig. 33. — Diagram summarizing the relations between rainfall and crop yields at Hays, Kans.

Crop year 1923

Precipitation :

Annual, 8 per cent above

Seasonal, 42 per cent above

Crop yields:

Winter wheat, 71 per cent below

Barley, 58 per cent above

Milo, 164 per cent above

Corn, 120 per cent above

Very little of the winter wheat emerged in the fall and that
was very late. The final stand was very poor, weeds offered
serious competition, growth was slow, and the wheat finally
succumbed to the most severe attack of stem rust ever experienced
in the section. Conditions were very favorable to all other
crops. Frost-free period, 172 days.

Crop year 1924

Precipitation :

Annual, 13 per cent below

Seasonal, 61 per cent below

Crop yields:

Winter wheat, 16 per cent above

Barley, 20 per cent below

Milo, 44 per cent below

Corn, 60 per cent below

By the middle of May, winter wheat began to show signs of
lack of water, and from that time until harvest there was not
water enough to overcome the checked habit of growth, but
the crop filled well. Spring-sown srnall grains suffered from
poor stands and from a lack of water. The lack of water during
the growing season accounted for the low yield of corn. Milo
suffered from the same cause. Many plats failed to make a
stand. Frost-free period, 137 days.

RESULTS AT HAYS, KANS.
[Altitude, 2,000 feet; 18-year period (figs. 32 and 33)]

Climatic conditions: Mean annual precipitation, 21.59 inches;
mean seasonal precipitation, 11.77 inches; mean seasonal
evaporation, 46.562 inches.

Average frost-free period, 163 days.

Soil: Clay loam.

Number of crop yields averaged each year: Winter wheat, 40;
barley, 15; kafir, 26; corn, 21.

Average annual crop yields per acre: Winter wheat, 18.2
bushels; barley, 19.9 bushels; kafir, 19 bushels; corn, 6.1
bushels.

11810°— 27-

50

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1907

Precipitation:

Annual, 25 per cent above

Seasonal, 25 per cent above

Crop yield:

Winter wheat, 36 per cent below

Barley, 100 per cent below

Kafir, 13 per cent above

Corn, mean.

Corn was killed by a freeze on May 27 and replanted June 3.

Winter wheat suffered from spring drought. Barley was

destroyed by soil blowing and spring drought. Frost -free

period, 159 davs.

Crop year 1908

Precipitation:

Annual, 6 per cent above

Seasonal, 21 per cent above

Crop yields:

Winter wheat, 13 per cent above

Barley, 41 per cent below

Kafir, 100 per cent below

Corn, 3 per cent above

Grasshoppers injured corn, particularly by eating the silks.
Barley suffered from drought before harvest. Winter wheat
was about normal. Kafir did not germinate; replanted but
did not make a stand. Frost-free period, 168 days.

Crop year 1909
Precipitation :

Annual, 24 per cent above

Seasonal, 31 per cent above

Crop yields:

Winter wheat, 100 per

cent below

Barley, 100 per cent

below

Kafir, 30 per cent below, .
Corn, 146 per cent above.

There was long-continued drought in the spring during which
small grains suffered much from soil blowing. Small grains
were finally destroyed by hail on June 13. Winter wheat on
fallow plats located so they were not destroyed by soil blowing
was estimated before the hailstorm to promise a yield of 30
bushels. Corn was about a foot high at the time of the hail-
storm and only partly recovered from it. Kafir was replanted
after the hailstorm and made a fair crop, although it was too
late to attain its fullest development. Frost-free period, 164
days.

Crop year 1910
Precipitation:

Annual, 3 per cent below

Seasonal, 20 per cent below

Crop yields:

Winter wheat, 79 per cent above

Barley, 22 per cent above

Kafir, 46 per cent above

Corn, 16 per cent above

Corn suffered some from drought and was damaged more or
less by chinch bugs and grasshoppers, but the most serious
damage to it was by hot winds when it was in tassel. These
prevented fertilization. Winter wheat suffered a little from
drought in April and again just before harvest, which was on
June 24. The development of kafir was about normal. Barley
suffered a little from drought preceding harvest. Frost-free
period, 178 days.

Crop year 1911
Precipitation:

Annual, 35 per cent below

Seasonal, 46 per cent below

Crop yields:

Winter wheat, 93 per cent below

Barley, 99 per cent below __

Kafir," 92 per cent below

Corn, 100 per cent below

Ml crops started nicely in the spring, but the rainfall was bo
light that all the small grains began to suffer early in May.
The continued drought —accompanied by high temperatures and
hot winds, together with attacks of chinch bugs, grasshoppers,
and jack rabbits damaged the crops to -such an extent that all

were practically failures,' although a little grain was produced

on plats fallowed the year before. The loss of the grain BOrghumS
was chicllv due to the chinch bugs, while the drought alone was
probably sufficient to account for the greater part of the loss of
corn and small grains. Frost-free period, h'>0da\s.

Crop year 1912

Precipitation:

Annual, 3 per cent below

Seasonal, 23 per cent below

Crop yields:

Winter wheat, 20 per cent below...

Barley, 32 per cent above

Kafir, 19 per cent above

Corn, 57 per cent below

Winter wheat made rank growth until about the middle of
May, when it began to suffer from drought and hot winds. It
appeared ripe before it headed. Spring grain did not suffer so
soon, but dried up before harvest. Barley was also injured by
chinch bugs. Corn and the sorghums suffered from chinch
bugs and grasshoppers. Corn suffered more than kafir and
was also blown down by wind. Frost-free period, 133 days.

Crop year 1913

Precipitation:

Annual, 1 per cent below

Seasonal, 7 per cent above

Crop yields:

Winter wheat, 61 per cent below

Barley, 64 per cent below

Kafir, 100 per cent below

Corn, 100 per cent below

Conditions were favorable for corn until the end of June.
Hot winds, grasshoppers, drought, and chinch bugs entirely
destroyed it between July 4 and July 15. Drought and hot
winds prevented the production of grain, and grasshoppers
destroyed the fodder. Winter wheat made a good growth of
straw, but drought in the later stages of development greatly
reduced the yield of grain. There was much run-off from the
rain of May 2. Kafir and milo were destroyed by chinch bugs
assisted by grasshoppers. Frost-free period, 188 days.

Crop year 1914

Precipitation :

Annual, 9 per cent below

Seasonal, 13 per cent below

Crop yields:

Winter wheat, 14 per cent above

Barley, 24 per cent below

Kafir, 52 per cent below

Corn, 46 per cent below

Winter wheat suffered somewhat from drought in May and
again in the latter part of June, but yielded above the average.
Barley and other spring-sown small grains suffered from drought
in June. Kafir grew normally until about the heading stage in
the latter part of July. It had then exhausted its supply of soil
water. Unbroken save by occasional light showers, the drought
continued until the kafir had matured. Hot winds at tasseling
time prevented fertilization in corn, and very little grain was
formed. Frost-free period, 165 days.

Crop year 1915
Precipitation :

Annual, 41 per cent above. .

Seasonal, 78 per cent above..
Crop yields:

Winter wheat, 5 per cent be-
low

Barley, 79 per cent above

Kafir, 16S per cent above

Corn, 189 per cent above

Winter wheat grew very heavy straw, but the grain yield was
reduced by lodging and hail damage. Barley was thought to be
damaged more than the wheat by the hail, but evidently it
recovered better. Conditions wore very favorable to both corn
and kafir. Frost-free period, 1S5 days.

Crop year 1916

Precipitation:

Annual, 12 per cent below

Seasonal, 12 per cent below

Crop yields:

Winter wheat, 82 per cent above

Barlex , 26 per cent below

Kafir, t>7 per cent below

Corn, 62 per cent below

Winter wheal suffered some from drought in May, but condi-
tions were generally favorable for it. Spring-sown small grains
Buffered serious damage by green i>ug>.. Green bugs, chinch

bugs, grasshoppers, and drought were too much for corn and the

sorghums. Frost-free period, 149 days.

CEOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

51

Crop year 191)

Precipitation :

Annual, 45 per cent below

Seasonal, 41 per cent below

Crop yields:

Winter wheat, 69 per cent below. _

Barley, 95 per cent below

Kafir, 93 per cent below

Corn, 80 per cent below

Little or no grain was produced except where planted on
fallow. Small grains suffered from drought in June and corn
and the sorghums in July. Kafir was so delayed by the drought
that it was frosted before much seed matured. Frost-free
period, 153 days.

Crop year 1918

Precipitation :

Annual, 12 per cent above

Seasonal, 2 per cent below

Crop yields:

Winter wheat, 21 per cent below

Barley, 41 per cent above

Kafir, 88 per cent below

Corn, 77 per cent below

Winter wheat suffered from wind and drought in the middle of
May. By June 15 all small grains were suffering severely from
drought and drying up rapidly. The drought continued until
small grains were harvested. Corn dried up in August without
earing, and only a small percentage of the kafir headed. Frost-
free period, 142 days.

Crop year 1919
Precipitation:

Annual, 23 per cent above

Seasonal, 28 per cent above

Crop yields:

Winter wheat, 14 per cent below

Barley, 94 per cent above

Kafir, 45 per cent above

Corn, 46 per cent below

Small grains responded to favorable moisture conditions with
a very heavy vegetative growth, but there was practically no
rain after June 12 until they were matured or dried up. Both
the quantity and the quality were injured. The heavy growth
of winter wheat was lodged and injured by hail on May 2. The
drought continued until September 17. Corn dried up, and the
development of the sorghums were retarded. Frost-free period,
176 days.

Crop year 1920
Precipitation :

Annual, 14 per cent below

Seasonal, 14 per cent below

Crop yields:

Winter wheat, 72 per cent above.

Barley, 73 per cent above

Kafir, 206 per cent above \

Corn, 170 per cent above

The season of 1920 as a whole was one of the most favorable
experienced at this station, and crops yielded far above their
averages. Frost-free period, 155 days.

Crop year 1921

Precipitation :

Annual, 21 per cent above

Seasonal, 13 per cent above

Crop yields:

Winter wheat, 79 per cent above. .

Barley, 47 per cent above.

Kafir, 102 per cent above

Corn, 85 per cent above

Barley was injured more than other crops by a spring frost
and also suffered from a dry spell in the latter part of May.
A second drought in the latter part of July and the first part of
August checked the development of the grain sorghums, but
was not serious in its results. Corn dried up rapidly during
this drought period and was practically dead by August 13,
when the drought was broken by a heavy rain. Frost-free
period, 158 days.

Crop year 1922

Precipitation :

Annual, mean.

Seasonal, 21 per cent above

Crop yields: %

Winter wheat, 52 per cent above

Barley, 77 per cent above

Kafir, 6 per cent below

Corn, 39 per cent above

The distribution of the precipitation was very favorable to
small grains, as indicated by the yields obtained. It was not,
however, so favorable for cultivated crops, as there were no
good rains after July 9. Frost-free period, 174 days.

Crop year 1923

Precipitation:

Annual, 33 per cent below

Seasonal, 8 per cent below

Crop yields:

Winter wheat, 100 per cent below

Barley, 3 per cent below

Kafir, 10 per cent below _

Corn, 100 per cent below

The drought which began the previous July continued un-
broken until April 24. This made winter wheat too late to
develop much of a crop. With no reserve of water in the soil,
the seasonal precipitation was not sufficient for the needs of the
small grains. The spring-sown grains were dried up during
the latter part of June, and finally all spring-sown small grains
were completely destroyed by hail June 29. Winter wheat
outside of the hail area succumbed to rust. Row crops were
badly damaged by the storm. One of the driest Julys in 56
years followed. Corn made no ears. The sorghums recovered
from the hail and survived the drought sufficiently well to be
able to respond to the August and September rains and produce
some fair yields. Frost-free period, 180 days.

Crop year 1924

Precipitation:

Annual, 4 per cent above

Seasonal, 44 per cent below

Crop yields:

Winter wheat, 129 per cent above.

Barley, 87 per cent above

Kafir, 39 per cent above

Corn, 16 per cent above

The precipitation in June was the lowest on record for that
month. The soil was well filled with water from the preceding
fall, the spring was early, and the average yield of winter wheat
was the highest in the history of the station. Its growth was
checked somewhat by drought in May, and its maturity was
hastened by drought in June. The yield of barley was reduced
by chinch bugs. Row crops began to show the lack of water
by the last of July, and during August corn was so badly
damaged that it made but little grain. Sorghums survived
conditions better. Frost-free period, 155 days.

RESULTS AT GARDEN CITY, KANS.

[Altitude, 2,836 feet; 16-year period (figs. 34 and 35)]

Climatic conditions: Mean annual precipitation, 19.01 inches;
mean seasonal precipitation, 14.26 inches; mean seasonal
evaporation, 52.152 inches.

Average frost-free period, 167 days.

Soil: Sandy loam.

Number of crop yields averaged each year: Corn, 17; milo, 13;
kafir grain, 23; kafir total, 23.

Average annual crop yields per acre: Corn, 7.9 bushels; milo,
18.1 bushels; kafir grain, 13 bushels; kafir total, 3,776 pounds.

Crop year 1909

Precipitation:

Annual, 8 per cent above

Seasonal, 3 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 100 per cent below

Kafir grain, 100 per cent below

Kafir total, 35 per cent above

The season was very dry until May 20. Some plats of small
grains survived and produced straw, but the dry weather in the

52

MISCELLANEOUS CIBCULAB 81, I". S. DEPARTMENT OF AG L'RE

GARDEN CITY (KANS-) FIELD STATION

YEAR,' 5

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
\ EAR

CROP YIELDS "°p

4

C 99

2.72

0.23

0.30

0.35 J 2.15

0 c?

2 50

3.44

5.10

1 31

-.

2059

CORN
MILO

o.o'

3

1908

19C9

2

KAFIR GRAIN

00

1

-rr*r-

■ slL . ^ .

fST — Hi

_ M . —

-J^r

1 KAFIR TOTAL

51060

4

0.68

3.77

0.70

0.50

0.25

0.00

1.04

1.52

3.23

2 00

2.99

0 14

1682

| CORN

0.0

1910

1909

3

Tmilo

15.5

2

Tkafir grain

5.8

1

_

B ■!■-.■

m _

PkAFIR TOTAL fs3l3.0

4

0.00

0.15

0.00

0 00

3.53

0.89

0.32

3.19

0.61

1.84

1.68

0.23

12.44

| CORN

0.0

191 1

J

Tmilo

0.0

1910

'

KAFIR GRAIN

0.0

,

KAFIR TOTAL

924.0

I '

1 • ■ I 1

. «.[

i i i i ,

1 t ■ 1 1

1 ■ _j|

. i M ■

■ ■ . ■ ,,.,,,.

** BmH H

. M .

1911

4

1.85

0.95

1.66

0.28

3.04

0.98

2.55

0.S6

4.07

1.76

3.49

1.34

2253

CORN

0.0

1912

3

MILO

27.7

2

KAFIR GRAIN

24.2

1

1 M

,., |

■*j

KAFIR TOTAL

7185.0

1912

4

0.33

0.29

0.05

0.15

1.15

0.50

1.21

2.30

3.12 V 4.97

0.87

5.47

20.41

CORN

»00

1913

3

MILO

0.0

2

KAFIR GRAIN

0.0

i

— ', , w

KAFIR TOTAL

1 143.0

1913

4

0.23

1.19

2.42 n

027

0.20

0.03

1.74

3.63

1.44

0.56

0.64

0.15

12.50

CORN

1.7

1914

3

MILO

S.7

2

KAFIR GRAIN

4.6

1

— s~BP— — ■ ■

KAFIR TOTAL

2630.O

1914

A

1.48

0.00

0.41

0.45

2.54

0.93

2.67

4.39

2.96

1.66

2.27

2636

CORN

31.0

1915

3

MILO

28.6

2

KAFIR GRAIN

21.8

1

— r, B~

— ■ ;

±il|-

Sq — B9_ . a 1 _BW

KAFIR TOTAL

4956.0

4

1.79

■ .12

0.13

1 09

T.

0.60

2.80

0.40

4.21

0.20

3.89

1.16

1639

CORN

0.0

1916

3

MILO

KAFIR GRAIN
KAFIR TOTAL

4.0

2.9

2190.0

1915

■

■

■

■

■

■

1

I

-JJ

■ ■

. ■ . ,

iBi , . i i

. i. . i. . .

.■.«

_ _■ m UVm. m

M H ■ 1 ■

^h_

i tat •■ i

1916

4

0.67

T. —

0.51

- 0.30

-<-T.

0.60

2.74

3.27

1.19

2.96

2.99

1.13

16.36

CORN

0.0

1917

3

MILO

3.oj

2

KAFIR GRAIN

0.8

I

—5

"-—

KAFIR TOTAL

2393.0

1917

4

0.13

0.30

0.16

0.34

0.64

2.21

0.79

2.48

1.91

3.58

0.64

2.00

15.18

CORN

0.0

1918

3

MILO

3.S

2

KAFIR GRAIN

3.1

—

4

3.23

0.13*

U 3.10*

■■ . . .

0.18

- 1.52

1.S3

2.24

0.86

0.60

3.00

1.12

3.20

20.71

CORN

'J 6

1919

■

MILO

34.3

1918

■

■

■

■

■

KAFIR GRAIN

22.8

-i.

fa

■

■

■

J;

— t

>j^[

L - . .

fcfcd

— n-

— I"

KAFIR TOTAL

4622.0

1919

4

1.6S

0.72

0.00

0.20

0.23

0.21

1.24

2.47

3.27

3.49

3.12

2.55

19.15

CORN

22.0

1920

J

MILO
KAFIR GRAIN

40.0
32.9

2

l

JL=z

— ■ _■

J|

■ !■■!■

KAFIR TOTAL

6657.0

1920

A

2.83

0 86

0.43

1 02

0 32

T.

2.63

0.96 5.81

2.21

2.25

2.46

21.78

CORN

16.1

1921

3

MILO

288

?

— B—

KAFIR GRAIN

20.3

1

_ „ ,

»I~

KAFIR TOTAL

3537.0

4

0.20

0.00

0.65

0.24

0.19

1.35

3.55

3.31

0.64

2.05

2.49

0.07

1474

_CORN_
MILO

_ 9.5
"~21.7

1922

1921

3

2

KAFIR GRAIN

17.7

1

Jn — ■*■>

IKAFIR TOTAL

3946.0

1922

«

0 00

0.49

T.

T.

T.

0.41

3.92

6 69

6 88

4.52

3.86

6 19 K

3296

CORN
MILO

11.8
34.8

1923

1

2

KAFIR GRAIN
KAFIR TOTAL

20.2
3203.0

1

1923

4

3.10

0.33

0.29

T.

0 76

1.73

2.08

1.06

1 39

1 09

1.74

1.73

1530

CORN

MILO

19.1
42.6

1924

t

2

KAFIR GRAIN

30.8

1

-aM—M

■

_■ '■

KAFIR TOTAL

5223.0

AVERAGE

1 20

075

0 67

033

0 92

088

1.97

248

280

256

2 48

1.97

1901

MONTH

OCT.

NOV.

DEC

JAN

FEB

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT

TOTAL
YEAR

*Hall

Fig. 34.— Relations between annunl crop yields and predpItatlOD, by Qve-day, monthly, and crop-year periods, il ilio ti.irdrn City I K:ms .1 Field Station

CEOP YIELDS ASD PRECIPITATION IN THE GEEAT PLAINS ABEA

53

BUSHELS
INCHES

( Garden City, KanS. )

57
54
5 1
48

1 l

~T

1

s

Seasonal t vaporation -^

— ---

— --

S
S

X

^ S"

"* o f~\ i— > w 1 it i r"\ C

/

\^v\\jv i i

_ uuo

Si
\

/

42
39
36
33
30
27
24
2 1

\

s

/

.

j:

Milo -*}}.

•

I

'.

•

;' \

»

•

\. \

•••

•«f^*

• X •

\ '* V *

•

f

j?- Kafir

\

f 1 %

• j*r**V

% *

t Total

* T§*?~ *

X

t+F

fi

\

** *

* •

■ i

* •

■ .

r*jr \

/ o* ix

\

< Ex,

xxlxx

~>;

•&

A-/* f/fl 7"0 TA L MEAN

18
1 5
1 2

9
6

3

n.

«jEL \^

4tX

V;

MILO MEAN

xxxxxxxxxx^

^ ' \

7,w?» Ax I x, x ,', 7js4.Cv.xl

^-c-r*rT

M*"

„,i,

KAFIR MEAN

&

' easonal ^

7"

-\

I

5 '•

Y"

Pr<

icipitation

**
*.

•V

-*

3>*

t4

£ KafirS

•♦«;■

***

•^

5

t

S923 '15 '12 '21 '19 '09 '13 '20 '10 '16 'i7 '24 '18 '22 '14 'II

Fig. 35.— Diagram summarizing the relations between rainfall and crop yields at Garden City, Kans. (See text, p. 51)

latter part of June and the first of July prevented it from filling.
Corn, kafir, and milo made a good growth of stalks, but drought
and hot winds in August prevented the formation of grain.
Frost-free period, 164 days.

Crop year 1910

Precipitation:

Annual, 12 per cent below

Seasonal, 23 per cent below

Crop yields:

Corn, 100 per cent below !

Milo, 14 per cent below

Kafir grain, 55 per cent below

Kafir total, 41 per cent above

Winter wheat was destroyed in the fall by grasshoppers and
jack rabbits. Some of the spring-sown small grain had a good
growth of straw, but the water supply was not sufficient to
mature any of them properly. Corn made a good growth of
fodder, but did not have water enough or was unable to with-
stand the hot winds sufficiently to set grain. Kafir and milo

had good stands and a heavy growth of stalks, but the September
drought interfered with the development of grain. Frost-free
period, 163 days.

Crop year 1911

Precipitation:

Annual, 35 per cent below

Seasonal, 45 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 100 per cent below

Kafir grain, 100 per cent below

Kafir total, 75 per cent below

Crops were unable to survive the drought and produce grain.
Weekly notes show that most of the small grains were gone by
the middle of June, that corn and the sorghums were beginning
to suffer decidedly by the first of July, that corn was fired
beyond the possibility of recovery by July 22, and that most of
the sorghums were practically dead by August 19. Frost-free
period, 159 days.

54

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

\A/OOD\A/ARD iOKLA.) FIELD STATION

VEAR

a

OCT.

NOV.

DEC.

JAN.

_FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1914

4

1.96

0.06

0.77

1.1 7

3.44

1.45

■J6-S3

5.29

2.43

3.14

3.62

5.74

35.60

W. WHEAT

27 4

1915

3

■

MILO

354

■

2

_

_

JhBrB B- = ■—

KAFIR GRAIN

372

1915

1
4

2.36

ij ^ —

0.S5

0.06

1.5 0

0.03

0.82

JUL

1.78

1.70

f 10.26

0.00

B i ■ 1

1.02

2.34

22.42

KAFIR TOTAL
W.WHEAT

26

1916

3

MILO

9.2

2

KAFIR GRAIN

53

1

m L ,_,

.,,,,,.

_ ; j jfc

1 ,

rfB _ 1 =

nr m~

KAFIR TOTAL

33300

1916

4

1 .71

0.75

0.60

0.20

0.20

0.1 0

1 .58

1.03

1.37

1.13

6.65

2.72

18.04

W.WHEAT
MILO

90
23 3

1917

3

2

«

KAFIR GRAIN

249

flH —

1

;, -~^-

i_i pit ~

, ^ , ,

— nsns

„ , K^.B , —

MM

-BlV

KAFIR TOTAL

72920

1917

4

0.05

0.67

0.01

1.60

0.29

2.09

2.22

4.00

1.9 1

0.73

1.35

1.24

16.16

W.WHEAT

78

1918

2

MILO

62

2

KAFIR GRAIN

69

1

■.,«,.'

1 , , , 1 ,

^g ^

f-

KAFIR TOTAL

27050

1918

4

3.35

1.53

2.92

0.06

1.53

1.94

4.1 0

4.2 9 I 2.2 2

1.35

1.87

0.63

25.79

W.WHEAT

147

1919

3

MILO

223

3

2

ft

KAFIR GRAIN
KAFIR TOTAL

203
46080

E

■

3t lb

1

-mli

JLjl

tA

-»=»-

dtln

fltl

1919

4

1.85

2.37

0.00

1.03

0.0 7

0.6 1

1.06

3.40

1.29

-4.69

3.00 L5.0 1

24.38

W.WHEAT

135

r— =

1920

3

i

MILO

21.3

2

— rl —

KAFIR GRAIN

327

1

S&L^_*_

-B—rH

l/ff KLiH ,

KAFIR TOTAL

8007.0

1920

4

2.55

1.32

1 .E3

2.22

0.61

1 .33

1.80

1.91

5.78

2.50

2.94

29.6C

W.WHEAT
MILO

28 4

~ 30~2~

1921

2

H5.11

■

■

2

■3

d£ im~

■

KAFIR GRAIN

30.4

■

■

!

~flltW

■

■

■

KAFIR TOTAL

6108.0

"Tm in' ■

. . . ■

>>, IR i

^jjL

H ufl ■_■_]

■£A ■ 1

■ ._.

i

0.01

0.00

0.1 1

1.02

0.96

5.08

2.97

3.69

0.1 8

1.07

2.31

2.83

20.23

W.WHEAT

250

1922

1921

3

■

■

MILO

11.0

■

■

2

n

■

n

KAFIR GRAIN

9 5

_n

■

■

1

bS .,.

ritzA

■

■

KAFIR TOTAL

36130

.■!■■■

■ • . t i

..iii

.11. , ..

, ... _a

JHfcEta

JLjU

■i , ......

M^n , ., piifl i i . l_

■>...

1922

4

0.74

1.15

0.00

0.00

0.06

1.86

2.32

8.1 1

4.20

0.69

0.39

9.33B J28.85

W.WHEAT

183

1923

3

■ 1

MILO

52

w

IH 1

2

■ HI

- tm S

KAFIR GRAIN

135

|

"

v BH B ■

HI

1

1

5 MB B 38

IK 1

KAFIR TOTAL

35SSO

■a. i.i ■

a«

III

1 1 1 I •

,,,,..

ijffil i i

— 1

■>■

rti.HJR »i>

m> . ^

BS I

1923

4
3

T

0.89

0.84

0.03

0.81

2.96

3.14

0.78

1.46

3.07

3.40

3.22

32.59

W.WHEAT

190

1924

MILO

274

[{-11.99

■

■

KAFIR GRAIN

27.3

■

iJti-

-J-

. KAFIR TOTAL

40610

AVERAGE

2.66

0.93

0.68

0.88

0.80

1.82

2.75

3.42

3.11 I 1.84

2.87

3.61

25.37

MONTH

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE I JULY

I

AUG.

SEPT.

TOTAL
YEAR

Fig. 36.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Woodward (Okla.) Field Station

Crop year 1912

Precipitation:

Annual, 19 per cent above

Seasonal, 3 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 53 per cent above

Kafir grain, 86 per cent above

Kafir total, 90 per cent above

The season of 1912 was especially favorable for all crops
except corn, which fired badly at tasseling lime the latter part
of July and did not set ears. Frost-free period, 15C> days.

Crop year 1918

Precipitation:

Annual, 7 per cent above

Seasonal , 26 per cent above

Crop yields:

Corn, 100 per cent below

Milo. 111(1 per cent below

Kafir grain, 100 per cent below

Kafir total, 70 per cent below.

Although the precipitation was above the mean, the season
was hot and dry. Most of the July precipitation of 1.97 inches

w a-- lieavx .

came in a single hail and rain storm, and run-off .
The September rainfall of nearly BH Inches came too late to
help crops. Winter wheal was eaten by birds in the fall.
Spring-sown small grains on fallow promised a crop until Julj 1.
when they were destroyed by a hailstorm. Corn was killed
at the same lime. The sorghums were so badly injured that

they were doI able to recover enough to make a crop in the hoi

dry weather that followed, continuing through July and August.
Frost-free period, 16S days.

Crop year 1914

Precipitation:

Annual. 34 per cent below

Seasonal, 43 per cent below

Crop yields:

Corn, 7S per cent below.

Milo, 68 per cent below

Kafir grain, 65 per cent below

Kafir total, 30 per cent below

The distribution of the precipitation favored the small grains.
Winter wheal was harvested by June 20 without serious sull'erini
foi water. Spring-sown small grains were later and sufferei
more The continued drought of July, August, and September
was too much for corn and the sorghums. Frost-free period, 185
da\ s.

Crop year 1915
Precipitation:

\nnual. 39 per cent above. .

Seasonal, 11 per cent above.

Crop yields:

Corn, 292 per cent above. . \

Milo. 58 per cent above

Kafir grain, (iS per cent

above

Kafir total, 31 per cent

above.

Small grains and corn produced profitable crops for the

fust time. The corn crop did not suffer serious injury from

CROP YIELDS AND PRECIPITATION IN THE GKEAT PLAINS AREA

55

BUSHELS
INCHES

(Woodward, OK/a.)

1915 '24- '21 '23 '19 '20 '!6 '22 'i7 '18

Fig. 37. — Diagram summarizing the relations between rainfall and crop yields at Woodward, Okla. (See test, p. 56)

lack of water at any time during the season. Water conditions
were favorable to the sorghums, but temperatures were too low
during the greater part of the season for the best results with
these crops. Only about 25 per cent of the kafir matured fully.
Frost-free period, 185 days.

Crop year 1916

Precipitation :

Annual, 14 per cent below

Seasonal, 11 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 78 per cent below

Kafir grain, 78 per cent below

Kafir total, 42 per cent below

General climatic conditions throughout the season were very
adverse to the growth of all crops. From about the middle of
June to the middle of August there were no rains of value to
crops. About the only winter wheat to harvest was on fallow.
Most of the spring-sown small grains were crowded out early in
the season by Russian thistles. Corn began to fire badly about
the middle of July and dried up, being harvested early in August.
The dry condition of the surface soil made it difficult to obtain
good stands of the sorghums. It was necessary to replant many
of the plats, and some of the seed did not germinate until after

the heavy rain of August 15. Rains came too late and in in-
sufficient quantities to enable any of the sorghums except those
on fallow to produce much grain. The little that was threshed
was immature and of poor quality. Frost-free period, 169 days.

Crop year 1917

Precipitation :

Annual, 14 per cent below

Seasonal, mean.

Crop yields:

Corn, 100 per cent below

Milo, 83 per cent below

Kafir grain, 94 per cent below

Kafir total, 37 per cent below

Winter wheat failed to survive the dry winter and spring.
All spring-sown small grains were complete failures. A dry
June with hot winds dried them up without heading or prevented
the heads from filling. There was a severe hailstorm on June 5,
but the small grains were small and apparently soon recovered
from the injury. The first growth of corn was checked by the
hail. By August 1 drought had dried it up and chinch bugs had
eaten much of it. The sorghum crops were damaged by dry
weather and chinch bugs to the extent that they produced
grain only when planted on fallow. Frost-free period, 154 days.

56

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1918

Precipitation:

Annual, 20 per cent below

Seasonal, 20 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 81 per cent below

Kafir grain, 76 per cent below

Kafir total, 63 per cent below

Winter wheat and rye failed to survive the winter. Spring-
sown small grains failed almost completely as a result of drought
and hot winds. Only a few plats of wheat on fallow were har-
vested. A shortage of water checked the growth of corn before
maturity, and no grain was produced. Grasshoppers damaged
it considerably. Poor stands of sorghums were obtained, and
they made slow and irregular growth in the early season. They
ran out of water later and produced practically no grain and but
little forage. Frost-free period, 179 days.

Crop year 1919

Precipitation :

Annual, 9 per cent above

Seasonal, 23 per cent below

Crop yields:

Corn, 85 per cent above

Milo, 90 per cent above

Kafir grain, 75 per cent above

Kafir total, 22 per cent above

The ground was covered with snow from December until
March, and there was a good supply of water in the soil in the
spring. Winter wheat suffered somewhat from a lack of water
in May and June, but yielded more than its average. Spring
grains did well until about the middle of June, when hot winds
and a lack of water dried them so that only poor yields of light
and shrunken grain were obtained. Dry weather during the
summer reduced the yield of corn. The corn earworm attacked
all the ears that were formed, and as a result the quality was poor.
The sorghums did not suffer much from a lack of water during
the summer and had good, well-filled heads. Frost-free period,
176 days.

Crop year 1920

Precipitation :

Annual, 1 per cent above

Seasonal, 13 per cent above

Crop yields:

Corn, 178 per cent above

Milo, 121 per cent above

Kafir grain, 153 per cent above.

Kafir total, 76 per cent above. _

Winter wheat was killed by late freezes and high winds in
April, and spring-sown small grains suffered from a lack of
water in June, but corn and the sorghums developed under
exceptionally favorable conditions and yielded well. The
quality and probably the yield of corn suffered from the usual
ravages of the corn earworm. Frost-free period, 155 days.

Crop year 1921

Precipitation:

Annual, 15 per cent above

Seasonal, 14 per cent above

Crop yields:

Corn, 104 per cent above

Milo, 59 per cent above

Kafir grain, 56 per cent above

Kafir total, 6 per cent below

Work with spring grains was discontinued except one plat of
each. Winter wheat was injured by late freezes and high winds
in April. The yield of corn was greatly reduced by hot winds in
August. The grain was of poor quality and badly infested with
the corn earworms. Milo and kafir were injured considerably
by hot winds and drought in August when they were at about
the heading stage. Frost-free period, 174 days.

Crop year 1922

Precipitation:

Annual, 22 per cent below _

Seasonal, 15 per cent below

Crop yields:

Corn, 20 per cent above

Milo, 20 per cent above

Kafir grain, 36 per cent above

Kafir total. 5 per cent above

Conditions in 1922 were favorable to the production of winter
wheat. All corn plats were badly burned by the end of July, and
yields were small and quality poor. After August 8 there was
almost no precipitation during the growing season. High tem-
peratures and the lack of water in the latter part of August and
in September reduced the yields of sorghums. Frost-free period,
171 days.

Crop year 1923
Precipitation :

Annual, 73 per cent above

Seasonal, 125 per cent above

Crop yields:

Corn, 49 per cent above

Milo, 92 per cent above

Kafir grain, 53 per cent above

Kafir total, 15 per cent below

The drought beginning in August, 1922, was not broken until
April 26. Beginning with the latter date and continuing
through the season, there was much wet weather. There were
many torrential rains and much run-off. The dry fall preceding
prevented a stand of winter wheat. Spring-sown small grains
did not produce satisfactory yields. Wet weather delayed the
planting of corn and the sorghums until later than usual. They
were severely damaged by hail on August 4. Corn did not
recover as well as the sorghums. Kafir did not recover as well
as milo. The quality of the sorghums was injured by wet
weather at and after harvest time. Frost-free period, 182 days.

Crop year 1924
Precipitation :

Annual, 20 per cent below

Seasonal, 36 per cent below

Crop yields:

Corn, 142 per cent above

Milo, 135 per cent above

Kafir grain, 137 per cent above

Kafir total, 38 per cent above

The soil was well filled with water from the previous year, the
rainfall was well distributed, and no long period of drought was
recorded. The yield of winter wheat was one of the best on
record at the station. Corn was damaged to some extent by
a hot wind on June 18, but the plants were so small that they
soon recovered. Milo made the highest average yield recorded
at the station. The average yield of kafir was lowered somewhat
by the poor yield of fisted plats, which washed so badly that it
was necessary to replant one. Frost-free period, 137 days.

RESULTS AT WOODWARD, OKLA.

[Altitude, 1,893 feet; 10-year period (figs. 36 and 37)]

Climatic conditions: Mean annual precipitation, 25.37 inches;
mean seasonal precipitation, 17.60 inches; mean seasonal
evaporation, 49.6S0 inches.

Average frost-free period, 204 days.
Soil: Loamy sand.

Number of crop yields averaged each vear: Winter wheat, 20;
milo, 25; kafir grain, 32; kafir total, 32.

Average annual crop yields per acre:
bushels; milo, 19.2 bushels; kafir grain
total, 5,140 pounds.

Crop year 1915
Precipitation:

Annual, 40 per cent above

Seasonal, 52 per cent above

Crop yields;

Winter wheat, 65 per cent above

Milo, 84 per cent above

Kafir grain, 79 per cent above

Kafir total, 56 per cent above

Winter wheat, 16.6
20.8 bushels; kafir

Cold, wet weather made replanting of most of the grain
sorghums necessary. The final stand, especially of milo, was
poor. This was partly caused by moles (pine mice?). Sor-
ghums were very late in maturing. Frost-free period, 225 days.

Crop year 1916
Precipitation:

Annual, 12 per cent below

Seasonal, 3 per cent below.

Crop yields:

Winter wheat, 84 per cent below

Milo, 52 per cent below

Kafir grain, 75 per cent below

Kafir total, 35 per cent below

Over half of the precipitation for the year fell in the 30 days
from May 26 to June 24, inclusive. Following the latter date

CHOP YIELDS AND PBECIPITATTON IN THE GBEAT PLAINS AREA

57

there was no rainfall until August 7. The only good crop was
broomcorn. Winter wheat suffered from the May drought
and was injured an estimated 25 per cent by hail. Corn and
the sorghums suffered from the drought beginning June 24
and continuing with little relief through the season. Milo also
suffered from chinch bugs. Frost-free period, 193 days.

Crop year 1917
Precipitation :

Annual, 29 per cent below

Seasonal, 18 per cent below

Crop yields:

Winter wheat, 46 per cent below

Milo, 21 per cent above

Kafir grain, 20 per cent above

Kafir total, 44 per cent above

The rainfall previous to August 7 was very deficient. This
resulted in the failure of corn and spring-sown small grains and
in a low yield of winter wheat. Plentiful rains began about the
time the sorghums were heading, and good crops of them were
matured. Frost-free period, 190 days.

Crop year 1918
Precipitation :

Annual, 36 per cent below

Seasonal, 35 per cent below

Crop yields:

Winter wheat, 53 per cent below

Milo, 68 per cent below

Kafir grain, 67 per cent below

Kafir total, 47 per cent below

This was the driest year in the history of the station and the
yields of all crops were low. Frost-free period, 200 days.

Crop year 1919

Precipitation :

Annual, 2 per cent above

Seasonal, 18 per cent below

Crop yields:

Winter wheat, 11 per cent below

Milo, 16 per cent above

Kafir grain, 2 per cent below

Kafir total, 10 per cent below

The season was very late, active field work not beginning
until in May, at which time there was ample moisture in the
soil. The water supply was scanty after July 1, and conditions
became critical a number of times, but were sufficiently relieved
each time to allow crops to mature normal yields. Frost-free
period, 231 days.

Crop year 1920
Precipitation :

Annual, 4 per cent below i

Seasonal, 5 per cent above

Crop yields:

Winter wheat, 19 per cent below

Milo, 11 per cent above

Kafir grain, 57 per cent above

Kafir total, 56 per cent above

The precipitation was fairly well distributed. The most
pronounced dry period was in the latter part of July and the
first of August. Milo appeared to suffer more than other
crops. The average yield of wheat was reduced by soil blowing
and cultivation to prevent blowing. Frost-free period, 202 days.

Crop year 1921

Precipitation :

Annual, 17 per cent above

Seasonal, 14 per cent above

Crop yields:

Winter wheat, 71 per cent above

Milo, 57 per cent above

Kafir grain, 46 per cent above

Kafir total, 19 per cent above

The precipitation was fairly well distributed except for a period
in the latter part of July and the first of August, when crops
suffered slightly. Frost-free period, 206 days.

Crop year 1922

Precipitation:

Annual, 20 per cent below

Seasonal, 26 per cent below

Crop yields:

Winter wheat, 51 per cent above

Milo, 43 per cent below

Kafir grain, 54 per cent below

Kafir total, 30 per cent below

The dry fall gave winter wheat a poor start on most methods,
but excessive precipitation in the spring enabled it to mature a
good crop. Rainfall during the growing season for cultivated
crops was not sufficient for their needs and yields were very low.
Temperatures were very high and evaporation the highest
recorded at the station. Frost-free period, 174 days.

Crop year 1923
Precipitation:

Annual, 14 per cent above

Seasonal, 42 per cent above

Crop yields:

Winter wheat, 10 per cent above

Milo, 73 per cent below

Kafir grain, 35 per cent below

Kafir total, 31 per cent below

Climatic conditions were very unfavorable to most crops.
The total precipitation was high, but its distribution was bad.
From June 19 to September 10 it amounted to only 1.22 inches.
Winter wheat ripened June 15. It was not well filled. The
lack of rain during the growing season for other crops resulted
in very poor yields. Frost-free period, 205 days.

Crop year 1924

Precipitation:

Annual, 28 per cent above

Seasonal, 14 per cent below

Crop yields:

Winter wheat, 14 per cent above

Milo, 43 per cent above

Kafir grain, 31 per cent above

Kafir total, 21 per cent below j.

The crop-year precipitation was very high, but 11.99 inches of
it came in October, 1923. The seasonal precipitation was below
normal, but its distribution made conditions fairly favorable for
most crops. Frost-free period, 210 days.

RESULTS AT DALHART, TEX.

[Altitude, 3,978 feet; 16-year period (figs. 38 and 39)]

Climatic conditions: Mean annual precipitation, 18.68 inches;
mean seasonal precipitation, 14.43 inches; mean seasonal evapora-
tion, 51.828 inches.

Average frost-free period, 177 days.

Soil: Sandy loam.

Number of crop yields averaged each year: Corn, 17; milo, 19;
kafir grain, 16; kafir total, 16.

Average annual crop yields per acre: Corn, 13.4 bushels; milo,
23.1 bushels; kafir grain, 19.1 bushels; kafir total, 5,819 pounds.

Crop year 1909
Precipitation:

Annual, 29 per cent below

Seasonal, 24 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 77 per cent below

Kafir grain, 100 per cent below

Kafir total, 14 per cent below

The soil was very dry. Winter wheat did not survive. Spring
grains on most methods were ruined by the drought, and their
destruction was completed by hail on June 11. Corn was 8 to
10 inches tall at the time of the hail and was badly cut, but made
a rapid recovery. About the time it began to suffer from
drought it was ruined by a high wind and temperature of 104° F.
Milo and kafir were not seriously damaged by the hail. They
began to show effects of drought about August 1. Most of them
did not head. Frost-free period, 159 days.

Crop year 1910
Precipitation:

Annual, mean.

Seasonal, 1 per cent below

Crop yields:

Corn, 5 per cent below

Milo, 55 per cent above

Kafir grain, 87 per cent above

Kafir total, 130 per cent above

Some winter wheat plats were destroyed by soil blowing in the
winter and the remainder by hail on May 21. Spring grains
were killed by soil blowing, were reseeded, and the second plant-
ing was ruined by hail. Corn and the sorghums were not planted
until the last of May and encountered generally favorable con-
ditions. Plats by some methods suffered from drought for a few
days in July and more seriously in September. Frost-free period,
178 days.

58

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
DAI-HART (TEX.) FIELD STATION

YEAR

s

OCT.

NOV.

DEC.

JAN.

FEB.-

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

T908

4

0.29

0.93

0.06

T.

0.28

0.71

0.18

1.70

■ 5.10

1.27

0.65

2.12

13.29

CORN

0.0

1909

3

■

MILO

5.41

■

2

■

KAFIR GRAIN

0.0

■ _

!

■ I

■

■ ■

KAFIR TOTAL

50300

I M

■

'-■ ■ ™ •

I 1 ■

lal 1 rw

,., H*

._■-■.

_■ ■

n ■ ■

1909

4

2.60

1.21

0.15

0.20

0.03

0.12

1.51

2.96

4.04

2.48

3.28

0.05

18.63

CORN

127

1910

3

MILO

35.8

2

_ II ■

KAFIR GRAIN

356

I 1 H ■

'

8 1 ~

S- — 1 — _§**-

KAFIR TOTAL

133630

-

0.00

p.07

0.02

0.00

0.54

0.43

0.59

3.37

0.28

3.65

1.87

0.58

11.40

CORN

07

1911

3

MILO

12.7

1910

2

KAFIR GRAIN

8.5

t

' ,

, , , , ,

=-

KAFIR TOTAL

4510.0

1911

4

1.72

0.25

1.28

0.00

1.30

0.76

2.56

2.37

3.36

1.6S

2.64

1.98

19.90

CORN
MILO

13.0
34.9

1912

3

2

KAFIR GRAIN

6.4

■ =-1

— I"

J

1912

4

0.05

— ' ' ■ i— 1
■0.00

. ..■ ,
0.03

0.C5

1 1 Mfk

■ 0.14

rr H

0.02

0.88

2.35

1.29

0.85

1.50

1.45

8.62

CORN

0.0

1913

3

MILO

1.7

2

KAFIR GRAIN

S.5

1

— --

B ■■

KAFIR TOTAL

3158.0

1913

4

0.1 s

1.78

3.18

0.05

T.

T.

3.98 _

T ?0«S

3.65 _

2.58

1.33

0.32

24.40

CORN

23.3

1914

3

I

MILO

50.2

■

n

2

J

B 1

Li,

1 1

KAFIR GRAIN

346

1914

4

3.00

_,...■
0.00

0.56

0.19

0.72

0.42

5.15

£*5s!Ls

2.58

-— i Bfta B.i
2.15 | 3.70

■

2.11

1.21

21.79

KAFIR TOTAL
CORN

8664.0
456

1915

3

■

MILO

36 9

■

2

■

KAFIR GRAIN

38.7

B

1

■

KAFIR TOTAL

7894.0

III

,11.1

— n i

ii — iii.

' ' ^ll !■

m . . .i i

^5Bl^£L^«

tm mkm

. . . ■■

1915

4

2.60

0.10

0.01

0.44

.0.00

0.12

1.49

0.69

4.42

2.55

3.45

0.72

16.59

CORN

87

1916

3

MILO

17.1

2

KAFIR GRAIN

153

KAFIR TOTAL

4911.0

'

. H i i

> . 1 .

.11,.

i > m ,

1 I

<

0.22

0.03

0.37

0.14

0.09

0.03

0.37

2.70

0.93

1.64

2.28

1.28

10.08

CORN

08

1917

1916

3

MILO

8.7

2

KAFIR GRAIN

3 0

1

-=

—

*^J

—m-r

-■

KAFIR TOTAL

20440

1917

«

0.31

1.02

0.00

0.27

0.05

2.85

0.89

4.87

1.23

1.49

1.67

1.49

16.14

CORN

0.0

1918

3

MILO

16.1

■

2

■

KAFIR GRAIN

112

■ 1

n

■

1

1 M

■

=zH

^^M^ttzmbs

^ —

U — —

KAFIR TOTAL

33090

1918

4

1.87

0.25

1.74

0.09

0.96

3.16

3.48

2.75

1.88

2.41

3.45

27.16

CORN

14.0

1919

3

■

MILO

34.3

■

2

■

KAFIR GRAIN

296

- s

_ B

1

P^-

fc-

i Ml

— n-

kzJL

-M:

r- — ■-

KAFIR TOTAL

51240

1919

4

2.50

1,14

• T.

0.36

0.43

0.05

0.32

3.25

' 6.81

2.56

1.33

0.81

19.56

CORN

19.2

1920

3

MILO

261

2

~t '

1 B 1

-■■>.. —

KAFIR GRAIN

222

1

-fc

1 1

Iftfl

fc+T

KAFIR TOTAL

5638.0

■■ , .

K *■ JE

.1.1.

H.i t

^Mm i •

<

■i

W& ■

Inl

JB _ .

H , , ,

1920

4

4,49 -

0.34

0.08

1.80

0.08

0.15

0.76

3.70

■ 5.82

5.12

0.69

0.04

23.07

CORN

239

1921

3

MILO

233

2

KAFIR GRAIN

248

1

_ — k .

KAFIR TOTAL

5444 0

1921

4

0.54

0.00

0.26

0.37

0.67

0.73

5.20

5.06

3.40

1.57

1.88

0.52

20.20

CORN

9.0

1922

3

2

•■

i-!

fa

KAFIR GRAIN

159

1

-

■_

^iF"

LJL

« I

. ■ 1

■=-

fcfc:

KAFIR TOTAL

4460 0

1922

.;

0.15

0.36

0.02

0.00

1.03

1.72

4.09

1.78

6.05

0.87

2.10

25 09

CORN

19 5

1923

3

MILO

22 7

i

KAFIR GRAIN
KAFIR TOTAL

267

74~70 0~

1

-Lr-

* '

, i .

[ 1 — ._

,

i Mm

§§■« i.i

1923

4

■ 6 29

1.23

1.32

0.05

0.09

1.61

1.16

2.44

0.69

1.32

5.00

1.72

22.92

CORN

13.71

1924

3

I

MILO

r 22.6"

■

2

■

KAFIR GRAIN

29 3

■__

— ■ — -

■

i M-&

i .

'

--■-

u ii J| M

■ ., m m

Jul

=-lT

KAFIR TOTAL

5873 0

AVERAGE

1.68

0.54

0.57

0.25

0.40

0.81

2.04

3,2

3.19.

2.23

2.51

1.34

18.68

MONTH

OCT.

NOV

DEC

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT

TOTAL
YEAR

Fw. 38.— Relations between uuuu.il crop yields uud precipitation, by five-day, monthly, and crop-yeat periods, at the Dalhart (Tex.) Field Station

CHOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

59

BUSHELS
INCHES

(Da/harf, Texas)

1919

'23 '14- '24- '21 '15 '22 '12 '20 '10 '16 '18 '09 'II '17 '13

Fig. 39. — Diagram summarizing the relations between rainfall and crop yields at Dalhart, Tex. (See text, p. 57)

Crop year 1911

Precipitation :

Annual, 39 per cent below

Seasonal, 28 per cent below

Crop yields:

Corn, 95 per cent below

Milo, 45 per cent below

Kafir grain, 55 per cent below.

Kafir total, 22 per cent below '

The low yields in 1911 were the direct result of drought.
The season started under very adverse conditions. The precipi-
tation for the eight months from September to April, inclusive,
was only 1.70 inches. The May rainfall was sufficient for itself,
but not to overcome the deficiency in June. Small grains were
almost destroyed by hot winds on June 7 and 8. Only a few
plats of oats on fallow headed, and they did not fill. Corn
suffered more than the sorghums in the drought preceding the
rains in July, Frost-free period, 169 days.

Crop year 1912

Precipitation :

Annual, 7 per cent above

Seasonal, 1 per cent above

Crop yields:

Corn, 3 per cent below

Milo, 51 per cent above

Kafir grain, 56 per cent below

Kafir total, 7 per cent above

The season opened with more than the usual amount of water
in the soil. With the rains that fell during the growing season
this carried most of the cultivated crops through to maturity
with little damage from drought. The small grains suffered from
soil blowing, but promised fair yields when they were destroyed
in the milk stage by hail on June 17. Cultivated crops were
young and recovered from the hail. The variety of Standard
kafir used was too late for the cool season. Frost-free period,
198 days.

60

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Crop year 1913

Precipitation:

Annual, 54 per cent below

Seasonal, 42 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 93 per cent below

Kafir grain, 82 per cent below

Kafir total, 46 per cent below

The precipitation for both the crop year and the season of 1913
was the lowest in the history of the station. This was doubtless
the cause for an almost complete crop failure, since conditions
were otherwise normal. The only method that provided water
stored from the previous season was fallow, and the only grain
produced was by this method. Frost-free period, 168 days.

Crop year 1914
Precipitation :

Annual, 31 per cent above

Seasonal, 33 per cent above

Crop yields:

Corn. 74 per cent above

Milo, 117 per cent above

Kafir grain, 81 per cent above

Kafir total, 49 per cent above

All tilings considered, the season was one of the most favorable
to crop production in the history of the station. By May 1 the
soil was wet to a depth of about 8 feet. Frost-free period, 17S
days.

Crop year 1915

Precipitation:

Annual, 17 per cent above..

Seasonal, 17 per cent above.
Crop yields:

Corn, 240 per cent above. A

Milo, 60 per cent above

Kafir grain, 102 per cent
above

Kafir total, 36 per cent above

The season was very favorable. The temperature was low.
The yields of small grains were light, but every plat seeded pro-
duced some grain. The corn yields were the highest in the
history of the station. The yields of the grain sorghums were
also among the highest obtained. None of the cultivated crops
suffered at any time from a lack of water. Frost-free period,
152 days.

Crop year 1916

Precipitation:

Annual, 11 per cent below

Seasonal, 8 per cent below

Crop yields:

Corn, 35 per cent below

Milo, 26 per cent below

Kafir grain, 30 per cent below

Kafir total, 16 per cent below

Kafir grain, 84 per cent below

Kafir total, 65 per cent below

It was very dry until June, and crops suffered again from
drought in July and the first of August. The August rainfall
enabled the sorghums to make fair crops. Low yields were the
direct results of a deficient water supply, but on the other hand
the distribution of the deficient supply prevented failures.
Frost-free period, 170 days.

Crop year 1917
Precipitation:

Annual, 46 per cent below

Seasonal, 36 per cent below

Crop yields:

Com. <t4 per cent below

Milo, 62 per cent below.

The season of 1917 was about two weeks later than the
average. The drought was extreme and continued throughout
the season. Most of the plate of small grain were destroyed by
a sand storm on May 25. Those that survived the storm dried
up a few weeks later. Corn was the only one of the cultivated
crops that it was not necessary to replant before a stand was
secured, The yield of corn was very li^ht, and the only grain

produced by kafir and milo was where they were planted on

fallow. Frost-free period, 158 days,

Crop year 191S

Precipitation:

Annual. 14 per cent below

Seasonal, 19 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 30 per cent below

Kafir grain, 41 per cent below.'

Kafir total, 43 per cent below

The low yields were the results of deficient precipitation.
Small grains all failed; corn was past recovery and the production
of grain by it impossible before the end of July; and some of the
earliest plantings of sorghums were definite failures before the
rains in early August, but later plantings were able to recover
and make fair crops. Frost-free period, 17S days.

Crop year 1919

Precipitation:

.Annual. 46 per cent above

Seasonal, 32 per cent above

Crop yields:

Corn, 4 per cent above

Milo, 48 per cent above

Kafir grain, 55 per cent above

Kafir total, 12 per cent below

The crop year was the wettest in the history of the station.
The precipitation was well distributed and sufficient to maintain
crops in good condition at all times. All crops, including
both winter and spring small grains, made good yields. Frost-
free period, 192 days.

Crop year 1920

Precipitation:

Annual, 5 per cent above

Seasonal, 5 per cent above

Crop yields:

Corn, 43 per cent above

Milo, 13 per cent above

Kafir grain, 16 per cent above

Kafir total, 3 per cent below

The distribution of precipitation was quite favorable to the
production of adapted crops. Small grains have practically
disappeared from the picture. The season was late on account
of dryness until the rains began in May. The precipitation in
June was the highest on record at this station, and in July and
August it was sufficient to keep the crops growing well enough
to mature and yield above the average. Frost-free period,
178 days.

Crop year 1921

Precipitation:

Annual, 24 per cent above

Seasonal, 12 per cent above

Crop yields:

Corn, 78 per cent above

Milo, 1 per cent above

Kafir grain, 30 per cent above

Kafir total, 6 per cent below

Precipitation was heavy in May, June, and July. All crops
were in excellent condition from the time they emerged until
after the middle of August. There was practically no rain in
August and September, and crops began to suffer. Early
plantings and early crops suffered little, but later plantings
suffered more and ripened prematurelv. Frost-free period,
178 days.

Crop year 191

Pri cipitation:

Annual, 8 per cent above

Seasonal, 22 per cent above..

Crop yields:

Corn, 33 per cent below - —

Milo, 111 per cent below

Kafir grain, Is per cent below.

Kafir total, 23 per cent below - —

The prcatcr part of the seasonal precipitation fell in the first
part of the season, and crops were suffering from drought before
the end of July. The weather continued hot and dr\ with only
small local showers which were not sufficient to relieve the situa-
tion. Some plats made good yields, and others were nearly fail-
ures. Winter rye and oats yielded well. Frost-free period, 195

days.

CROP YIELDS AND PRECIPITATION" IN THE GREAT PLAINS AREA

61

Crop year 1928

Precipitation :

Annual, 34 per cent above

Seasonal, 51 per cent above

Crop yields:

Corn, 46 per cent above

Milo, 4 per cent below

Kafir grain, 40 per cent above

Kafir total, 28 per cent above

Crop growth and development was checked by dry weather
in July and the first half of August. Excessive rains began on
August 1 and continued until after harvest. The crops started
a new growth, but maturity was much delayed by the wet cool
weather. Frost was late, but even then some crops did not
mature properly. Wet weather interfered with harvesting and
saved the crops. Rye and oats were failures. Frost-free period,
188 days.

Crop year 1924
Precipitation:

Annual, 23 per cent above

Seasonal, 15 per cent below
Crop yields:

Corn, 77 per cent above

Milo, 2 per cent below

Kafir grain, 53 per cent above

Kafir total, 1 per cent above.

The usual effects of a low seasonal precipitation were largely
overcome by the water stored in the soil from the excessive
rains of the preceding fall. Rye and oats were very poor and
were damaged by rabbits. Before heavy rains came, about the
middle of August, cultivated crops suffered from the deficient
precipitation. Frost-free period, 188 days.

RESULTS AT TUCUMCAEI, N. MEX.

[Altitude, 4,185 feet; 12-year period (figs. 40 and 41)]

Climatic conditions: Mean annual precipitation, 18.71 inches;
mean seasonal precipitation, 13.97 inches; mean seasonal evap-
oration, 54.635 inches.

Average frost-free period, 191 days.
Soil: Sandy "yucca land."

Number of crop yields averaged each year: Corn, 7; milo,
25; kafir grain, 11; kafir total, 11.

Average annual crop yields per acre: ' Corn, 16.6 bushels;
milo, 25.7 bushels; kafir grain, 18.7 bushels; kafir total, 3,668
pounds.

Crop year 1913
Precipitation:

Annual, 32 per cent below

Seasonal, 18 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 79 per cent below

Kafir grain, 78 per cent below.
Kafir total, 38 per cent below.

The soil was dry before the April rains, which wet it to a
depth of about 3 feet. Hail on June 12 did some damage to
the young crops, especially to cotton and cowpeas. It was
necessary to replant the latter. The month of July was the most
unfavorable of the season. Temperatures and wind movement
were high, and evaporation was excessive. Small grains were
destroyed by the dry weather and jack rabbits, the sorghum
crops were damaged some by plant lice, and the yields of the
sorghums were reduced to some extent by the attacks of birds.
Frost-free period, 184 days.

Crop year 1914
Precipitation:

Annual, 17 per cent above

Seasonal, 16 per cent above

Crop yields:

Corn, 95 per cent above

Milo, 90 per cent above

Kafir grain, 112 per cent above

Kafir total, 70 per cent above

The season opened with the soil well filled with water, the
rainfall was sufficient, and all crops grew steadily and rapidly
throughout the growing season. There was no apparent lack of
water until after most of the crops were matured. Frost-free
period, 188 days,

Crop year 1915

Precipitation:

Annual, 17 per cent above

Seasonal, 5 per cent above

Crop yields:

Corn, 91 per cent above

Milo, 92 per cent above

Kafir grain, 113 per cent above

Kafir total, 70 per cent above '.

A shortage of rainfall in May, June, and the first two weeks
of July affected small grains adversely. The rainfall from the
middle of July to the end of the season was sufficient, and
unusually good crops of the sorghums and corn were produced.
A hailstorm on August 15 damaged cowpeas so they were
attacked by disease and were necessarily harvested early. The
hail stripped the leaves of corn and the sorghums, but did not
seem to reduce their yields. Frost-free period, 188 days.

Crop year 1916

Precipitation:

Annual, 44 per cent below

Seasonal, 38 per cent below

Crop yields:

Corn, 67 per cent below

Milo, 37 per cent below

Kafir grain, 13 per cent below

Kafir total, 4 per cent below

August was the only month with adequate precipitation.
Soil blowing and planting in dry soil caused poor stands and
in some cases necessitated replanting. Late crops made some
fair yields, particularly of forage. The yields of the grain
sorghums were reduced by birds. Frost-free period, 194 days.

Crop year 1917

Precipitation:

Annual, 22 per cent below

Seasonal, 10 per cent below

Crop yields:

Corn, 34 per cent below

Milo, 15 per cent below

Kafir grain, 12 per cent above

Kafir total, 32 per cent above

The dry fall, winter, and spring caused much soil blowing.
Small grains failed. Cultivated crops started but made little
growth until the drought was effectually broken by the rains in
August. The first frost did not come until October 18, by which
time all crops were either mature or burning badly. Frost-free
period, 174 days.

Crop year 1918
Precipitation:

Annual, 47 per cent below

Seasonal, 39 per cent below

Crop yields:

Corn, 100 per cent below

Milo, 100 per cent below

Kafir grain, 100 per cent below

Kafir total, 77 per cent below

Crops could not be planted until July, and the first rain suffi-
cient to promote crop growth came on September 4. As a result
of these severe conditions all crop yields were light and in most
cases not worth harvesting. Frost-free period, 189 days.

Crop year

Precipitation:

Annual, 86 per cent above

Seasonal, 84 per cent above. ..

Crop yields:

Corn, 61 per cent above

Milo, 14 per cent above

Kafir grain, 26 per cent above
Kafir total, 3 per cent below...

1919

In the spring there were dela}Ts from wet weather and damage
from soil washing, and in the fall there was delay in harvesting
and damage to the crops from excessive rainfall. Yields were
uniformly good but not record breaking. Frost-free period,
203 days'.

62

MISCELLANEOUS CIECULAH 81, U. S. DEPAETilEXT OF AGRICULTURE

XUCUMCARI (N. MEX.) FIELD STATION

YEAR

|

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

-JULY

AUG.

SEPT.

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1S12

4

0.10

0.13

0.28

0.51

0.16

4. SI

1.11

2.80

0.42

1.71

0.94

12.67

CORN
MILO

0.0
55

1913

•>

?

KAFIR GRAIN

1

. St

KAFIR TOTAL

22730

1913

4

0.51

1.49

2.51

0.30

0.40

0.50

2.52

5.24

2.81

3.90

1.06

0.72

21.96

CORN

32.4

1914

3

MILO

48.8

2

KAFIR GRAIN

39.6

1

—

„ cjffl- fJW_

— '. — H — '. — : —

KAFIR TOTAL

6219.0

1914

4

3.48 _

T.

1.31

0.66

0.98

0.90

4.00

■ 1.59

0.71

3.13

2.28

2.94

21.98

CORN

31.7

1915

3

MILO

49.3

2

1

•^m

J

KAFIR GRAIN

39.S

1

J~i~fc"

Jd

1=^

1915

4

0.67

T.

0.27

0.70

' 1

0.09

1.55

■

0.56

i.i i n
0.63

0.98

4.43

0.56

10.44

CORN

5.5

1916

3

MILO
KAFIR GRAIN

16.1
16.2

2

m I

SB B

1

■ ,

G

dt=:

hi I

KAFIR TOTAL

3529.0

1916

4

0.78

0.29

0.32

0.31

0.11

0.12

0.32

1.82

0.90

0.74

PJ6.11

2.74

14.56

CORN

11.0

1917

3

■

MILO
KAFIR GRAIN

219
21.0

■

2

■

1

^

rfe

HEr

Lkd

KAFIR TOTAL

4831 0

1917

4

0.16

0.62

0.04

0.10

0.13

0.21

1.14

0.21

0.80

2.54

1.02

2.85

9.82

CORN

0.0

1918

3

MILO

0.0

2

KAFIR GRAIN
KAFIR TOTAL

825.6]

1

^■Lj ."

Jb=x

_ , , B~

1 J

„ i _B m

1918

4

2.60

0.51

2.00

0.04

0.32

3 " n

3.61

5.84

6.39

3.16

2.53

4.16

34.85

CORN

26.7

3

■

MILO

292

■

■

1919

2

B

D

■

KAFIR GRAIN

2i£

■

■

■

as*

1

z=jfc

— fc"

t4t

■■JL.

■

KAFIR TOTAL

3558.0

1919

4

2.31

0.51

0.93

0.76

0.15

0.34

0.20

2.55

3.91

1.52

1.48

1.44

16.10

CORN

23.3

1920

3

MILO

37.4

2

KAFIR GRAIN

, 20.2

1

bIB —

' — _ ,.

J,

—

nr —- 1 -**"■"— I

~ — Bpn — i-JBi — : — : — ; — "

KAFIR TOTAL

3302

1920

4

3.68

0.49

1.56

0.32

0.83

«■

F 5.88

3.65

1.86

0.75

27.74

CORN

26.0

1921

3

hi a

MILO
KAFIR GRAIN

44.7
22.4

iUn 1!

2

«p m

■

bh a

■

1

1UL-J

.

.

■ 1

dHLu-~ e

J^

_ ■

KAFIR TOTAL

43S&0

1921

4

0.21

T.

0.13

0.13

1.37

r 2.64

2.04

1.24

1.65

0.67

1.20

11.28

CORN

3.3

1922

3

MILO

10.9

2

KAFIR GRAIN

5.1

■

1

-t

zfc^S

B. -^

g^- m

^ ■

KAFIR TOTAL

1991.0

1922

4

0.37

0.93

0.96

1.04

3.35

1.92

3.55

0.63

5.64

1.78

20.17

CORN

17.0

1923

3

MILO

20.6

2

KAFIR GRAIN

14.6

■

1

^=—

fhm

— n

JL&L

^—

^■itr-

KAFIR TOTAL

3090.0

1923

4

^■7.51

1.69

1.64

0.19

0.60

0.63

1.67

2.07

1.93

3.79

1.31

23.03

CORN

22.2

1924

3

MILO

24.2

2
1

KAFIR GRAIN

17.8

I , , i n

JfcjE

,,_,,,

_^ , ^

_ ._.

rJ

— K0S

Jm afi^

KAFIR TOTAL

37 1 4.0

AVERAGE

1.87

0.54

0.76

0.40

-0.35

0.82

2.04

2.77

2.64

2.02

2.72

1.78

18.71

MONTH

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

FlG. 40.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Tucuoiicari (X. Mex.) Field Station

Crop year 1920

Precipitation:

Annual, 14 per cent below

Seasonal, 21 per cent below

Crop vields:

Corn, 40 per cent above

Milo, 46 per cent above

Kafir grain, 8 per cent above

Kafir total, 10 per cent below

From May until July there was plenty of moisture for planting
and getting the crops well started. There were dry spells during
the summer, but small showers which occurred from time to
time kept the crops progressing slowly. Frost-free period, 1SS
days.

Crop year 1921
Precipitation:

Annual, 48 per cent above

Seasonal, 49 per cent above

Crop yields:

< lorn, ">7 per cent above

Milo, 74 per cent above.

Kafir grain, 20 per cenl above

Kafir total, L9 per cent above

Rains did not begin in the spring until May 13, and there were
no effective rains after August 15. In spite of the lack of late
rains the crops filled very well and yields were much above the
average. Frost-free period, 197 days.

Crop year 1 !'.'.'

Precipitation:

Annual, 40 per cent below

Seasonal, 33 per cent below

Crop yields:

Corn, 80 per cent below

Milo, 68 per cent below

Kafir grain, 73 per cent below

Kafir total, 48 per cent below

At planting time, the middle to the latter part of May, there
was sufficient water in the soil to insure good germination.
By the latter part of June many of the plats were suffering
from lack of water. This condition became more pronounced
as i he season advanced, and the yields on all plats were greatly
reduced by it. Corn Buffered from a borer (Diutraca lincolata),
the corn earworm, and the cutworm, as well as from drought.
Frost-free period, 1S7 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

63

(Tucumcari N.MeX.)

1919 '21

Fig. 41. — Diagram summarizing the relations between rainfall and crop yields at Tucumcari, N. Mex. (See text, p. 61)

Crop year 1923

Precipitation:

Annual, 8 per cent above

Seasonal, 21 per cent above

Crop yields:

Corn, 2 per cent above

Milo, 20 per cent below

Kafir grain, 22 per cent below.
Kafir total, 16 per cent below.

Crop year

Precipitation :

Annual, 23 per cent above

Seasonal, 18 per cent below

Crop yields:

Corn, 34 per cent above

Milo, 6 per cent below

Kafir grain, 5 per cent below_
Kafir total, 1 per cent above..

192^

A severe drought during July and early August injured all
crops materially, and excessive rains throughout the fall delayed
maturity on many plats and resulted in much immature seed.
Corn suffered a severe attack b}^ borers, but made about the
average yield. Frost-free period, 209 days.

Planting was later than usual, because the surface soil was
dry during the spring. On many plats full stands did not
emerge until about July 1. Growth after that time was contin-
uous and normally rapid, but full maturity was not reached on
all plats. Corn was heavily infested with borers, but the damage
from it was not as great as in the two previous years. Frost-free
period, 196 days.

64

MISCELLANEOUS CIRCULAR SI, U. S. DEPARTMENT OF AGRICULTURE

AMARILLO (TEX.) FIELD STATION

YEAR S

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

-JULY

AUG.

SEPT lT0TAL
3tn. JYEAR

CROP YIELDS

CROP
YEAR

4

2 49

2 58

0 19

1 11

024

002

1 30

1 13

2 23

1 47

615 |

0 97 | 19.88

W. WHEAT

24

1907

1906

3

MILO

254

2

KAFIR GRAIN

138

9 B

1

fcjUt

— -Bjl rr-

--H

— — n^-

KAFIR TOTAL

^050 0

1907

4

164

0 69

1.46

0 26

0 72

T

1.86

3 44

1.73

4.64 J 3.39

1.50 1 21.33

W.WHEAT

14 2

1S08

3

MILO

40.8

2

KAFIR GRAIN

1 32.8

■

1

irat

■

KAFIR TOTAL

78000

B

B

■_ , .. . .

■ ■ ■ i i

. , . . |

^P

i fc^™—

1908

4

0.37

051

0.00

007

028

1.08

027

113

590

2.19

! 39

1 SO | 15.09

W.WHEAT

04

1909

3

MILO

69

2

KAFIR GRAIN

3.5

1

■ -

i ... . ■

1 .

..■ . m

— _

KAFIR TOTAL

30150

1909

4

1.18

325

054

0.05

0.17

0.41

0.53

2.61

1.48

2.61

2.48

005

15.34

W.WHEAT

78

1910

3

MILO

195

2

■

KAFIR GRAIN

130

■ 1

a

1

— tu

L-Ub-B-

., ,., , , ,

* R*_

. . ■ 1

KAFIR TOTAL 6055.0

1910

4

0.13

0.19

T

007

3.26

0.50

3.90 g

H^^ 0.35

5.92

2.54

1.30

24.90

W.WHEAT

2 5

1911

:

6.74 R

MILO

27.4

■

2

9

KAFIR GRAIN
KAFIR TOTAL

17 9
70240

■

1

. . .i .. i i

_ . . i i

.■.I

i Hai ■

. . —

K^^HH M

■JB. i ■

1911

4

153

0.55

1.14

T

1 S5

0.78

0.82

1.62

2.31

250

1.51

228

16.89

W.WHEAT

95

1912

3

MILO

270

2

KAFIR GRAIN

00

1

Ha u

iJ~~i~

KAFIR TOTAL

58800

1912

4

0.33

T

0.33

0.01

0.41

0 44

1.69

1.71

2.29

1.40

0.47

5.60

14.68

W.WHEAT

2 3

1913

3

MILO

00

2

KAFIR GRAIN

00

1

■ ■-« 1 i.K

. . • . i

... . ^

... . i .

■ H ' —

■ ■1.1 ■

i.i ,

8fa^»

1 1 ! .Hi

■ —

1913

4

0.63

226

2.17

T

0.01

0.02

1.27

3.83

0.65

1.90

2.52

1.10

16.56

W.WHEAT

183

1914

3

MILO

f 24.2

2

KAFIR GRAIN

94

1

=m

a IBS —

fc^h-rr-

~Bm ■

KAFIR TOTAL

43940

1914

4

398 H

0.00

387

0.29

1.49

058

4.89

2.03

1.16

3.74

4.S4

4.93 B

28.60

W.WHEAT

1C6

1915

3

■

■

MILO

KAFIR GRAIN

472
256

■

1

■

2

■

■

■

■

B

H

mB

■

1

■

"ad!

-

7TT-*B

■a

IX H

JL

KAFIR TOTAL

. s

■ It..

^■a

. , ■_■

JB9

»..--■

m, if .

_M_B_

i «

1915

4

1.02

0.25

0.05

017

0.00

0.56

182 0.86

2.70

1.17

•3.41

2.16

14.17

W.WHEAT

4.6

1916

3

MILO

126

2

KAFIR GRAIN

13.1

1

^^Hfi—

4t1-

KAFIR TOTAL

4806 0

1916

4

307

0.08

0.58

0.12

0.06

003

0.61

2.83

066

2.61

5.50

2.05

18.20

W.WHEAT

63

1917

3

MILO

15 0

2

KAFIR GRAIN

99

1917

4

031

055

0.01

0.13

0.29

0.86

048

2.39

1.19

2 69

2.20

0.74

11.84

W.WHEAT

00

1918

3

MILO

S9

2

■

■

KAFIR GRAIN

12

■

■

1

1 ■

■

. .-■

..til.

■ ...... -B

™> i

.,...■ m i i

■ J.B ■ ■ -

T^^fl

■ _ ,

B — .1

1918

4

2.24

0.83

3.13

0.05

0.66

0.84

2.52

2C3

3.53

239

3.43

472 1 26.37

W.WHEAT

108

1919

3

MILO

452

2

■

KAFIR GRAIN

30 9

■

1

... .Ht

ttJL

: —

.- ■ ■

JLb:

KAFIR TOTAL

52210

AVERAGE

1.47

0.90

0.81

0.18

0.73

0.47

1.69

Z49

2.01

2.71

3.05

2^5 ! 18.76

MONTH

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT TOTAL
3crl YEAR

1

Fig. 42.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Amarillo (Tex.) Field Station

RESULTS AT AMARILLO, TEX.

[Altitude, 3,676 feet; 13-year period (figs. 42 and 43)]

Climatic conditions: Mean annual precipitation, IS. 76 inches;
mean seasonal precipitation, 14.20 inches; mean seasonal evapo-
ration, 52.082 inches.

Average frost-free period, 189 days.

Soil: Heavy clay.

Number of crop yields averaged each year: Winter wheat, 15;
milo, 12; kafir grain, 10; kafir total, 10.

Average annual crop yields per acre: Winter wheat, 7.3
bushels; milo, 23.2 bushels; kafir grain, 13.2 bushels; kafir
total, 4,819 pounds.

Crop year 1907

Precipitation:

Annual, 6 per cent above

Seasonal, 7 per cent below

Crop yields:

Winter wheat, 67 per cent below

Milo, 9 per cent above

Kafir grain, 5 per cent above

Kafir total, 46 per cent above

Small grains were nearly destroyed by hail. Cultivated crops
made about average yields. Frost-free period, 1S7 days.

CHOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

65

BUSHELS

(Amarilfo, Tex.)

•19 'II 'OS '07 '17 '12 '14- '10 '09 '13 'Ifc.

Fig. 43. — Diagram summarizing the relations between rainfall and crop yields at Amarillo, Tex.

Crop year 1908
Precipitation:

Annual, 14 per cent above

Seasonal, 17 per cent above

Crop yields:

Winter wheat, 96 per cent above

Milo, 76 per cent above

Kafir grain, 149 per cent above.

Kafir total, 62 per cent above. -
One of the three best years in the history of the station.
Frost-free period, 192 days.

Crop year 1909
Precipitation .

Annual, 20 per cent below

Seasonal, 10 per cent below

Crop yields:

Winter wheat, 95 per cent below.

Milo, 70 per cent below

Kafir grain, 73 per cent below

Kafir total, 37 per cent below.

The fall, winter, and spring was a period of continued drought
which was not broken by heavy rains until about the middle
of June. The only small grains that survived and produced
anything were those on fallow. The latter part of the summer
was too dry for the development of corn and the sorghums under
general and ordinary methods of cultivation, but milo on summer
fallow gave about average yields. Frost-free period, 196 days.

11810°— 27 5

Crop year 1910

Precipitation:

Annual, 18 per cent below

Seasonal, 31 per cent below

Crop yields:

Winter wheat, 7 per cent above

Milo, 16 per cent below

Kafir grain, 2 per cent below

Kafir total, 26 per cent above

Winter wheat came through the winter in fair condition, but
suffered from drought except for a time in May. Spring grains
germinated very unevenly, some coming up shortly after seeding
in March and some not until after the rain in May. The sor-
ghums suffered from drought in the latter part of the season.
Frost-free period, 197 days.

Crop year 1911

Precipitation:

Annual, 33 per cent above

Seasonal, 46 per cent above

Crop yields:

Winter wheat, 66 per cent below

Milo, 18 per cent above

Kafir grain, 36 per cent above

Kafir total, 46 per cent above

Precipitation was high and yields of all crops except winter
wheat were good, but not in full proportion to the precipitation,

66

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

which was not well distributed. Winter wheat did not come up

in the fall and did poorly in the spring. Frost-free period, 209

days.

Crop year 1912

Precipitation :

Annual, 10 per cent below

Seasonal, 22 per cent below

Crop yields:

Wi nter wheat, 27 per cent above

Milo, 16 per cent above

Kafir grain, 100 per cent below

Kafir total, 22 per cent above

Precipitation for both the season and the crop year was below
the normal, but it was very well distributed. The season was
described as dry throughout, but no other factors interfered with
production. No stand of kafir was secured from the first plant-
ing, and the second planting was too late to mature. Frost-
free period, 153 days.

Crop year 1913
Precipitation :

Annual, 22 per cent below

Seasonal, 7 per cent below

Crop yields:

Winter wheat, 68 per cent below

Milo, 100 per cent below

Kafir grain, 100 per cent below

Kafir total, 84 per cent below

The precipitation for the crop year was only 14.60 inches, and
5.60 inches of this came in September, after crops had succumbed
to the drought. Milo on fallow produced a little grain, but it
was eaten by birds. A little winter wheat was harvested.
Frost-free period, 185 days.

Crop year 1914

Precipitation :

Annual, 12 per cent below

Seasonal, 21 per cent below

Crop yields:

Winter wheat, 150 per cent above. .

Milo, 4 per cent above

Kafir grain, 29 per cent below

Kafir total, 9 per cent below

Crops were benefited by the water stored in the soil from the
September, 1913, rains. Small grains made a good growth of
straw, but the yields were reduced by the hot, dry weather in
June. In spite of this the yield of winter wheat was the best in
the history of the station. Corn did not ear. Milo and kafir
suffered intermittently from drought and matured in the latter
part of August which was much earlier than usual. Kafir
especially suffered from a lack of water when the grain should
have been filling. Frost-free period, 191 days.

Crop year 1915

Precipitation:

Annual, 52 per cent above

Seasonal, 50 per cent above

Crop yields:

Winter wheat, 114 per cent above..

Milo, 103 per cent above

Kafir grain, 94 per cent above

Kafir total, 3 per cent above

The chief adverse conditions interrupting the generally favor-
able weather conditions were a late frost in May and a period of
drought in June. The frost chiefly affected winter wheat and
oats, and the dry, hot weather in June reduced the yields of all
small grains. Frost-free period, 191 days.

Crop year 1916

Precipitation:

Annual, 24 per cent below

Seasonal, 15 per cent below

Crop yields:

Winter wheat, 37 per cent below

Milo, 46 per cent below

Kafir grain, 1 per cent below

Kafir total, mean.

The grain sorghums made little headway until the rains begin-
ning August 19, which were in time to benefit them greatly.
Frost-free period, 193 days.

Crop year 1917

Precipitation :

Annual, 3 per cent below

Seasonal, mean.

Crop yields:

Winter wheat, 14 per cent below

Milo, 35 per cent below

Kafir grain, 25 per cent below

Kafir total, 21 per cent below

Very little water was carried over in the soil, and only three
or four rainy periods yielded precipitation sufficient to help
crops. Only one of these, the rainy spell of the second week
of May, was in time to help small grains. The drought in the
latter half of May and all of June resulted in a practical failure
of all the small grains. Corn and milo were suffering desper-
ately before relief came in the August rains. They recovered
to some extent, and the grain sorghums started a second growth,
but this did not fully mature before frost. Frost-free period,
166 days.

Crop year 1918

Precipitation :

Annual, 37 per cent below

Seasonal, 32 per cent below

Crop yields:

Winter wheat, 100 per cent

below

Milo, 57 per cent below

Kafir grain, 91 per cent below

Kafir total, 62 per cent below

The fall and winter were so dry that winter wheat did not
survive. Beginning the latter part of May, moisture conditions
became more favorable, but owing to the lack of stored water
in the soil a shortage existed throughout the season. The
showers were as a rule too light to give crops more than tempo-
rary relief. Small grains failed almost completely. Corn
failed to make any grain, and kafir was delayed until only a part
of it matured. Milo made some grain on all plats and a good
yield on some fallow plats. Frost-free period, 189 days.

Crop year 1919

Precipitation:

Annual, 41 per cent above

Seasonal, 31 per cent above

Crop yields:

Winter wheat, 48 per cent above...

Milo, 95 per cent above

Kafir grain, 134 per cent above

Kafir total, 8 per cent above

The yield of winter wheat and other small grains was reduced
somewhat by hail and that of winter wheat possibly by rust.
Corn made its usual poor yield of low quality. Milo aud kafir
developed normally. Frost-free period, 207 days.

RESULTS AT LAWTON, OKLA.

[Altitude, 1,200 feet; 9-year period (figs. 44 and 45)]

Climatic conditions: Mean annual precipitation, 2S.51 inches;
mean seasonal precipitation, 17.45 inches; mean seasonal
evaporation, 43.308 inches.

Average frost-free period, 214 days.

Soil: Heavy clay.

Number of crops averaged each year: Winter wheat, 26; lint
cotton, 27; kafir grain, 33; kafir total, 33.

Average annual crop yields per acre: Winter wheat, 16.6
bushels; lint cotton, 200 pounds; kafir grain, 16 bushels; kafir
total, 4,002 pounds.

Crop year 1916

Precipitation :

Annual, 28 per cent below.

Seasonal, 8 per cent below

Crop yields:

Winter wheat, 50 per cent below

Lint cotton, 42 per cent below.

Kafir grain, 80 per cent below

Kafir total, 41 per cent below

Small grains were injured by dry, windy weal her in March
and were ripened prematurely by dry weather in May and June.
The yields were also reduced by chinch bugs. Corn was

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

67

destroyed by chinch bugs. Sorghums suffered from drought in
the latter part of July and August, but probably would have made
fairly satisfactory yields if it had not been for chinch bugs,
which destroyed some and badly injured others. During the
severe conditions of summer there was a heavy abortion of
cotton squares, and only a top crop was produced. Frost-free
period, 194 days.

Crop year 1917

Precipitation :

Annual, 34 per cent below

Seasonal, 23 per cent below

Crop yields:

Winter wheat, 14 per cent below

Lint cotton, 17 per cent above

Kafir grain, 14 per cent below

Kafir total, 23 per cent above

Lack of water in the spring made it difficult to secure stands
and much late replanting was necessary. Heavy rain on May
30 enabled wheat to ripen normally. All chance for a corn crop
was destro3red by hot winds in the latter part of June and the
first of July. Other crops, including the first crop of kafir heads,
were badly injured at the same time. The first crop of kafir
heads were badly blasted and the greater part of the yield was
from later branch heads. Cotton stood the hot weather better
than other crops and suffered more from drought in the cool
weather of September than at any other time. Milo and corn
suffered more than other crops from chinch bugs. Frost-free
period, 189 days.

Crop year 1918
Precipitation :

Annual, 34 per cent below

Seasonal, 14 per cent below

Crop yields:

Winter wheat, 83 per cent below

Lint cotton, 100 per cent below

Kafir grain, 100 per cent below

Kafir total, 65 per cent below

Wheat was too severely damaged by drought and chinch
bugs to benefit from the 2.34 inches of rainfall in the first week
of June. Corn was planted April 9 and did very well until the
third week in June, when it soon yielded to hot parching winds
without forming many tassels. Some plats received much
injury from chinch bugs. All oat plats were heavily infested
with chinch bugs, which only hastened the effect of the drought
and hot winds. Hot winds and drought retarded the growth
of cotton and aborted squares as rapidly as they formed. Bolls
formed in September and October, too late in the season to
develop. Kafir, planted on May 6, made about normal growth
until the middle of June, when it was injured by hot winds and
chinch bugs and barely kept alive during the remainder of the
season. Most of it headed but did not make grain. Milo
succumbed more quickly and completely than kafir. Frost-free
period, 223 days.

Crop year 1919

Precipitation:

Annual, 41 per cent above

Seasonal, 25 per cent above

Crop yields:

Winter wheat, 53 per cent above

Lint cotton, 75 per cent above

Kafir grain, 74 per cent above

Kafir total, 39 per cent above

Precipitation was excessive, and the season was free from the
high winds and soil blowing in spring, the hot winds of summer,
and the attacks of chinch bugs. Winter wheat was damaged
somewhat by arm}' worms, which went to the corn as the wheat
ripened and did some damage there. Cotton was late and its
quality was injured by the excessive precipitation in October
and continued wet weather in November. Frost-free period,
246 days.

Crop year 1920
Precipitation :

Annual, 39 per cent above

Seasonal, 11 per cent above

Crop yields:

Winter wheat, 33 per cent above

Lint cotton, 97 per cent above

Kafir grain, 122 per cent above

Kafir, total, 54 per cent above

The quality of forage and grain was good. June and July
were dry, but the soil was well filled with water, and crops
suffered but little from drought. Wheat was infested with
chinch bugs, but its growth was so strong that they probably
reduced its yield but little. They did some damage to corn and
injured milo seriously. Frost-free period, 211 days.

Crop year 1921

Precipitation :

Annual, 12 per cent above

Seasonal, 12 per cent below

Crop yields:

Winter wTheat, 14 per cent below

Lint cotton, 28 per cent below

Kafir grain, 48 per cent above

Kafir total, 18 per cent above.

The season was favorable to crop growth until May, when
small grains suffered for water. Row crops had not made much
demand on soil moisture up to this time and were pushed along
in good condition by abnormal rainfall in June and about normal
precipitation in July. About the middle of July a severe drought
began that continued throughout the season. Hot winds and
high temperatures in August reduced the yields of row crops,
which began to show serious effects of the drought about the
10th of the month. The mild winter was apparently responsible
for an unusual number of insect pests which very noticeably
damaged small grains, sorghums, and cotton. Green bugs
damaged the winter wheat, chinch bugs damaged corn and the
sorghums, and boll weevils seriously infested the cotton. Frost-
free period, 207 days.

Crop year 1922

Precipitation :

Annual, 19 per cent below

Seasonal, 15 per cent above

Crop yields:

Winter wheat, 83 per cent below- _.

Lint cotton, 30 per cent below

Kafir grain, 87 per cent below

Kafir total, 52 per cent below

Fall and winter drought left the ground seeded to winter
wheat practically bare until the winter rains. The wheat was
injured by leaf rust and chinch bugs and died in the dry weather
of June. Corn and the sorghums were ravaged by chinch bugs
throughout the summer and suffered from high temperatures,
hot winds, and a shortage of water from June and thereafter.
The growth of cotton was satisfactory until the middle of July.
Lack of water after that time reduced the crop to a low yield,
short staple, and weak lint. Frost-free period, 239 days.

Crop year 1923

Precipitation :

Annual, 5 percent above

Seasonal, 13 per cent above

Crop yields:

Winter wheat, 30 per cent above

Lint cotton, 44 per cent below

Kafir grain, 42 per cent below

Kafir total, 33 per cent below

Winter wheat made a heavy growth of straw and matured
early in June without suffering from a lack of water. Heat and
drought, from the latter part of June to the last days of August,
cut the production of corn to a minimum. Milo was destroyed
entirely by chinch bugs. Hot winds, drought, and chinch bugs
reduced kafir to a low yield of very poor quality. Cotton suffered
from cold wet weather in the spring, webworms in June, drought
and grasshoppers in the summer, and excessive precipitation in
the fall. Frost-free period, 215 days.

Crop year 1924

Precipitation:

Annual, 18 per cent above

Seasonal, 6 per cent below

Crop yields:

Winter wheat, 131 per cent above

Lint cotton, 56 per cent above

Kafir grain, 81 per cent above

Kafir total, 57 per cent above

The only period of drought suffering was in the first 10 days
of August. The season was very free of the insect enemies that

68

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
LAVA/TON (OKL_A.) FIELD STATION

YEAR

a

X

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

191 S

&

0 85

0 09

0.11

234

003

119

3.52

1.61

406

460

087

1.11

20.58

W.WHEAT
L COTTON

83
11576

191.6

3

■

2

_ _

■

KAFIR GRAIN

32

1 ■ ■

1

fTTm

^ 1

~fc_

_jp-M

tin

KAFIR TOTAL

2377 0

1916

4

1.49

1.36

0.06

0.30

0.57

1.74

128

4.50

1.01

302

284

0.72

1889

W.WHEAT

14.21

1917

3

■

L COTTON

233.61

■

■

2

|

|

■

KAFIR GRAIN

138

■

■

■

■

1

-J-r

_^J_

.,,,,,

; ■ ■ ,

=-Itt-

_^m^M

-M±l

■ _,nff

=-1-

7»-K-

KAFIR TOTAL

49310

1917

4

0.19

103

003

0.20

0.25

2.16

2.36

1.29

3.08

2.57

1.48

4.18

18.87

W.WHEAT

2.8

1918

3

■

L COTTON

00

■

2

■

KAFIR GRAIN

0.0

■

1

i i '•'-<

B , , , B

■--_■

| _■ , :

KAFIR TOTAL

,- -

.... i

■ ■ H ■

i— i i.i i

VI

1 . , i ...

-•< «B

1918

T1

8 6B ■■

1.20

3.50

0.54

141

2.99

4.60

5.44

m 4.36

3.71

1.98

1.67

40.08

W.WHEAT

25.4

1919

3

1

■

L COTTON

349 0

■

■

■

2

■

■

■

asi

flfirt.

fc]

-JN

KAFIR TOTAL 5570 0

1919

ZflT^

2.25

0.92

1.04

0.61

1.64

3.14

■ 7.53

0.69

1.88

4.18

205 •

3991

W.WHEAT

22.1

1920

i

^■13.7eH

_

L COTTON

3940

■_ -M

1 ■

■ 1

III

KAFIR GRAIN
KAFIR TOTAL

355
61690

H n

■

■ ■ ■

fcj

l^i

-... ■■■

±Ji

- 1

r—m-M.. ..

1920

4

8 78 ^

229

0.66

1 15

1.47

2.05

2.14

1.30

593

2.95

0.83

2.13

31.88

W.WHEAT

142

1921

3

L COTTON

1450

2

KAFIR GRAIN

237

1

, „ a

^~ia^fcifcl _ .-■

■ ■

KAFIR TOTAL

47170

1921

4

0.03

T

0.53

0 89

0.46

0.97

6.85

P 6.63

1.01

3.40

0.64

1.61

23.02

W.WHEAT

28

3

L COTTON

140 0

■

1922

2

—■

■

KAFIR GRAIN

20

1

■■ , ..-

__

Jt^fc

,.-■■..

4rr-J

KAFIR TOTAL

19220

1922

4

2.46

1.04

0.21

4.37 4

070

1 30

3.48

5.56

2.68

1.25

179

4.99

29.83

W.WHEAT

215

3

L COTTON

1130

1923

2

KAFIR GRAIN

93

1

■ Km y -_y

t Ln

TTT*

HJH

KAFIR TOTAL

26730

1923

4

th

3.S1

1.76

0.20

0.1!

2.47

3.88

3.05

3.36

1.39

4.15

061

33.53

W.WHEAT

384

1924

3

— a

■

■

L COTTON

3130

— ■-

■

■

2

■ so*

■

■

KAFIR GRAIN
KAFIR TOTAL

29 0
6273 0

ffliw

7t=

fMf

H

r=lt—

aj-

AVERAGE

■■■.■

5.03

■ ■ i i.
1.43

0.89

123

0.62

1.86

3.47

4.12

2.91"

2.75

2.08

212

28.51

MONTH

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

Fig. 44.— Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Lawton (Okla.) Field Station

characterized other years. Persistent efforts were necessary to
control grasshoppers in the cotton plats. Frost-free period,
206 days.

RESULTS AT BIG SPRING, TEX.

[Altitude, 2,400 feet; 9-year period (figs. 46 and 47)]

Climatic conditions: Mean annual precipitation, 17.80 inches;
mean seasonal precipitation, 12.06 inches; mean seasonal evapora-
tion, 58.372 inches.

Average frost-free period, 212 days.
Soil: Sandy loam, high prairie.

Number of crop yields averaged each year: Milo, 38; kafir
grain, 12; kafir total, 12; cotton, 20.

Average annual crop yields per acre: Milo, 22.2 bushels; kafir
grain, 15.6 bushels; kafir total, 3,562 pounds; lint cotton, 206
pounds.

Crop year 1916
Precipitation:

Annual, 14 per cent below

Seasonal, 5 per cent below

Crop yields:

Milo, 12 per cent above

Kafir grain, 26 per cent above.
Kafir total, 72 per cent above.
Seed cotton, 64 per cent below

Winter wheat was cut short by drought, May was dry with
high winds, and June and the first 27 days of July were dry and
very hot. August was the most, favorable month of the summer
in regard to temperature and rainfall. Most crops in it too badly
burned by the drought revived and put on new growth. The
sorghums were the crops that revived t lie most. Most varieties
of cotton withstood the drought remarkably well, and if it had

not been for an attack of the bollworm, good yields would have
been obtained on all plats. Frost-free period, 195 days

Crop year 1911

Precipitation:

Annual, 61 per cent below

Seasonal, 65 per cent below

Crop yields:

Milo, 63 per cent below

Kafir grain, 94 per cent below

Kafir total, 89 per cent below

Seed cotton, 92 per cent below

The section represented by the Big Spring station was visited
in 1917 by the severest drought recorded since climatic records
have been kept. Practically the only production was fight
yields on fallow. Frost-free period, 165 days.

Crop year 1918

Precipitation:

Annual, 53 per cent below

Seasonal, 43 per cent below

Crop yields:

Milo, 90 per cent below

Kafir grain, 100 percent below

Kafir total, 63 per cent below

Seed cotton, 68 per cent below

The failures and low yields were the result of the second year
of continued extreme drought. Planting was completed and
stands obtained following the receipt of :>' _> inches of rain in the
first week of June. From this rainy period to the early part of
September less than half an inch of rain fell. New growth,
notably in kafir, after the September rains increased the yield of
forage. Frost-free period, 223 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

69

(Lawfon , OA/o.)

42

39

36

33

30

27

24

2 1

18

15

I 2

9

6

3

0-

Sept

r

/lug.
— Julu—

June

— ^^ AUG. -

JULY~~~ —

JUNE

r

'RECIPH

ATIAM

•^^

1

A 1 IUfN

May

_=^---

>*s^

"X.

ANNUAL MEAN

^\ ^^\l_ 1"^*^^^

MAY NT'

April

APR

^"^cr^^-ir^-^^^

— Mar.

■

■ L^\ T~c:=:::::::^

tt CROP YEAR

I

GROWING SEASON

WINTER
■EALL

jM' '*,„

^^^

~^~~^

^"--.^^

^\i^\

Dec.

~r~~

^---..^

—J^^^

*^c^ —

OCT.-NOV.-DEC

N

'

S

^v

— ^ — r

****<

"

- —

19

19 '20 '24 '21 '23 'ZZ '16 '17 '18

Fig. 45. — Diagram summarizing the relations between rainfall and crop yields at Lawton, Okla. (See text, p. 66)

Crop year 1919

Precipitation :

Annual, 73 per cent above

Seasonal, 91 per cent above

Crop yields:

Milo, 126 per cent above

Kafir grain, 114 per cent above

Kafir total, 70 per cent above

Seed cotton, 91 per cent above

Following two years of extreme drought the crop year was
the wettest in the history of the station. The precipitation
equaled that of the three preceding years combined. There was
some washing and loss of stands in June. The low precipitation
in July and the first three weeks of August caused the sorghum
crops to ripen rapidly, and most of them were harvested by the
middle of August. The excessive precipitation of September and
October caused much spoilage and loss to crops still in the field.
Frost-free period, 246 days.

Crop year 1920

Precipitation :

Annual, 35 per cent above

Seasonal, 21 per cent above

Crop yields:

Milo, 35 per cent above

Kafir grain, 81 per cent above

Kafir total, 60 per cent above

Seed cotton, 120 per cent above

Good rains in the fall and winter filled the subsoil with water,
but the surface was dry in the spring, and planting was delayed
until after the rains about the middle of May. Winter wheat
was harvested June 9. Dry hot weather in July caused all
crops to mature very rapidly. Most of the grain sorghums were
matured before the August rains came. Late-planted and late-
maturing crops were benefited by these rains and made larger
yields. Conditions especially favored cotton, which is a late
crop. Frost-free period, 213 days.

70

MISCELLANEOUS CIRCl'LAR 81, U. S. DEPARTMENT OF AGRICULTURE

BIG SRRINC3 (TEX.) FIELD STATION

YEAR

a

OCT.

NOV.

DEC.

JAN.

FEB. .

MARCH

APRIL

MAY

JUNE

-JULY

AUG.

SEPT.

TOTAL
YEAR

CROP YIELDS

CROP
YEAR

1915

4

1.33

0.00

0.67

0.13

0.00

1.74

2.12

0.14

1.59

2.48

4.31

0.87

15.38

MILO 24.9

1916

3

KAFIR GRAIN

19.6

2

KAFIR TOTAL

6137.0

1

-r-M-r

■ .. . .

— Hi- ■

LINT COTTON

75.0

1916

4

1.30

1.01

0.10

0.28

0.00

0.03

0.97

0.61

0.98

0.73

0.17

0.79

6.97

MILO

8.3

1917

3

KAFIR GRAIN

1.0

2

KAFIR TOTAL

388.0

1

LINT COTTON

16.0

B ■'

. . .■

-i.l I ! a

, «., ,.

; . i i i

fill;

■ mm .a

. — ... _ .

■l t ■

.•- i..i#t '■

■ Tt ■■ l

1917

4

0.00

0.12

0.00

0.60

0.73

0.09

0.10

1.19

3.53

0.16

0.24

1.66

8.42

MILO

2.2

1918

3

■

KAFIR GRAIN

0.0

■

2

■

KAFIR TOTAL

1323.0

■

1

Jf

LINT COTTON

65.0

i i _ if

I'll.

- -

■ , , .

— — • , I . la it

mm . . .

_ ... ,..

i ■■ i i H-

1918

4

1.99

0.74

1.32

0.57

0.06

3.06

1.45

1.43

H 8.28

0.95

3.60 _

«mm

30.88

MILO

50.1

1919

3

■

KAFIR GRAIN

33.*

■

2

■

■

KAFIR TOTAL
LINT COTTON

6C5A0
393.0

■

■

■—

1

■

■

HI

... Jt

m —

: tlhte

. ■ . _

■•■•..

m . Hi

... ■ _

i -rl_

am-

1919

4

6.31

0.78

0.09

1.97

0.20

0.12

0.08

5.32

1.33

0.91

6.30

0.69

24.10

MILO

KAFIR GRAIN

KAFIR TOTAL

29.9

28.3

5701.0

1920

3

■

2

i

■ 1

IL. I

Mb n

_ Hiii

■ ■ ■

LINT COTTON

454.0

B9H ..■_._

., i ■•■ i

mt-u .

I.H 1

i i i _

i i .....

■ BD i w

m 1 HL*

S - _

1920

4

1.95

2.22

0.20

0.25

0.90

1.15

0.11

3.69

. 2.77

0.45

0.85

0.71

15.25

MILO

21.5

1921

3

KAFIR GRAIN

16.3

2

H

■

KAFIR TOTAL

3074.0

■

1 I ■

1

-4vrrr

oj_ H

^7*-T

■■ ... ■ ■-

LINT COTTON

163.0

1921

4

0.23

T.

T.

0.38

0.08

2.36

2.89

0.38

0.22

0.00

21.04

MILO

25.3

1922

3

KAFIR GRAIN

18.2

2

KAFIR TOTAL

3251.0

1

, _ , ,

>i<i , _.

j -

- _ l_Lr — BB— ■. — ^M-

m . , . ,

LINT COTTON

199.0

1922

4

1.15

1.35

0.00

0.29

3.01

• 2.16

4.58

1 24

2.61

1.68

0.98

1.53

20.58

MILO

30.9

1923

3

KAFIR GRAIN

16.2

2

1 ■■

KAFIR TOTAL

2895.0

■

1

, — -

1-

_,,,.! .■ SB_

-iVr

J-T-

gj-

n _

--T^

LINT COTTON

322.0

1923

4

5.31

1.18

1.69

0.03

0.50

0.62

0.91

3.62

0.05

0.96

2.03

0.68

17.58

MILO

6.9

1924

3

KAFIR GRAIN

7.0,

2

KAFIR TOTAL

3237.0

^ tn

■

1 1 ■ J 1 ..■

— zrM-

rlHh

...■■■

^rJ-» —

LINT COTTON

188.0

AVERAGE

2.17

0.82

0.45

0.50

0.61

1.19

2.57

2.18

2.67

0.97

2.08

1.59

1730

MONTH

OCT.

NOV.

DEC.

JAN.

FEB.

MARCH

APRIL

MAY

JUNE

JULY

AUG.

SEPT.

TOTAL
YEAR

Fig. 46. — Relations between annual crop yields and precipitation, by five-day, monthly, and crop-year periods, at the Big Spring (Tex.) Field Station

Crop year 1921

Precipitation: •"" -r*

Annual, 14 per cent below

Seasonal, 29 per cent below

Crop yields:

Milo, 3 per cent below

Kafir grain, 4 per cent above

Kafir total, 14 per cent below

Seed cotton, 21 per cent below

Light precipitation in the spring of 1921 delayed the planting
of the main crops until after the middle of May. The rainfall
from May 14 to June 30 was ample to start the young crops into
vigorous growth, but drought and high temperatures in July,
August, and September reduced yields. Rain and hail on May
31 necessitated much replanting. Frost-free period, 174 days.

Crop year 1922

Precipitation:

Annual, 18 per ceni above

Seasonal, 55 per cent above

Crop yields:

Milo, 14 per cent above

Kafir grain, 17 per cent above

Kafir total, 9 per ceni below

i cotton, 3 per ceni below

0.6 inch of rain after July 1. Kafir did not withstand the
drought as well as milo. Frost-free period, 247 days.

Crop year 192S

Precipitation :

Annual, 16 per cent above

Seasonal, 5 per cent above

Crop yields:

Milo, 39 per cent above

Kafir grain, 4 per cent above

Kafir total, 19 per cent below

Seed cotton, 56 per cent aboVe

The soil wae -o .In in the fall and winter thai no fall planting

done and bu1 little tillagi accomplished until late in March.

The precipitation for the crop year and the season «as above

normal, but 12.77 inches came in April, more than 7.5 inches

falling within 21 hours. There was considerable run-off. Cot-
ion yielded very well, considering the fact thai il ; only

The season as a whole was favorable to the production of the
staple crops of the locality. The principal factor in determining
yields was dry weather in July and August. Kafir plats were
injured by birds. The quality of cotton and unthreshed grains
was injured by the heavy rains beginning in October. Frost-
free period, 214 days.

Cnij> year !■'
Precipitation:

Annual. 1 per cent below

Seasonal. 32 per ceni below
Crop yields:

Milo, 69 per cent below.

Kafir grain, 55 per cent below.

I\ ifir total, 9 per cent below..
>. ,• 1 cotton, 18 per cent below.

on did relativelj better than other crops, its yields
being only Is- per ceni below the '.'-year average. The yields
of other crops were very low. The controlling factor was the
extremely hoi and dry weather of June. July, and the first three
weeks of August. Frost-free peril I, 232 days.

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

71

BUSHELS
INCHES

66

63
60
57
54
51
48
45
42
39
36
33
30
27
24
21
18
15
12
9
6
3

(Big Spring, Texas)

____--'■

>•*

^v/ r*,sm^rs

■*•*
^

^t

--''"

S

s

S

x

N

■*"

„-~'~

>

**

-"

c

:rop yie

~ i r~> c

•

L

_ L.LO

V,

\ s Lint Cotton

V

♦,

\

rv

\

^ Kafir Tn fa/

*

+is"£- -ij:i~

/

'Z£

1 v >-.••*" /

ui iiV infill ni mi u,

tW7" COTTON MEAN-
M/LO MEAN

^ j.....^L.A

.j: j v.l...j :jr....;':L..:.v±-.* .

1

■v+. -

?S ' !s~J." • ' *»

¥ :• | * «

V+W SI Will

jL.„i.^L\:

\

KAFIR TOTAL MEAN-
KAFIR MEAN

a.^.^S^L^zr^r'S

WS^****4'' v«h3? "'.^'T "7**4

ffirzri

^^^-r

§
#*

*%£..

Seasonal Rainfall^

>^,\

j&v

^^*****_

^>8

+ VJS

^vxXXXXXX*

1919 '20 '22 '23 '24 '16 '21 '18 '17

Fig. 47.— Diagram summarizing the relations between rainfall and crop yields at Big Spring, Tex. (See text, p. 68)

RESULTS AT THE NORTHERN GROUP OF 16 STATIONS

GROUPING OF COMPOSITE CROP YIELDS

In the preceding pages four staple crops have been

used for comparison at each of the 23 stations located

in the 10 States lying wholly or in part within the

Great Plains area. Crop yields aggregating 28,400 in

number have been grouped into 1,235 average annual

yields per acre covering a period of time aggregating

303 years. Meteorological observations have been

made each day for a total of 110,595 days. The

precipitation for this period has been reported herein

in five-day, monthly, seasonal, and annual periods.

I It was, of course, impossible to use the same four

j crops at all stations, as no four crops could be found

j that are equaUy adapted to all parts of a region

| extending from Canada to Mexico.

This wealth of detailed information provides a
basis for many instructive and interesting studies and

comparisons of crop with crop at the same station, or
at other stations where the same crops were grown.
But the crop yields recorded in Figures 2 to 47 are not
sufficiently homogeneous to serve as a definite, quan-
titative basis for the study of the broad problem of
the relations between crop yields and precipitation.
It therefore was deemed desirable to regroup the data
from 16 of the northern stations where winter wheat,
spring wheat, and oats are staple crops, and to combine
these three crops into a single composite unit equivalent
to 1 bushel of wheat. This has been done by assuming
that 2^bushels of oats are equivalent to 1 bushel of
wheat. This assumption is fully warranted by the
yields obtained from these three crops at the 16 stations,
as shown in Table 3 (p. 4). The averages of these com-
posite yields for each of the 16 stations are summarized
in Table 5 (p. 73), and they are presented in detail for
ready comparison in Table 7 (p. 75).

72

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

RANK

2

4-

6

8

10

12

14

16

18

10

x

i

i
i
i
i
i

>

m

_i
o
o

LiJ

5

X

h
x
o

z

I

I
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I
I
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z
o

<

co
<

o
o
O

1

>

Id
_l
CU

O

o

u

LI
X
O

Q

<

i

2
O
co

Z

o

u

X

o

IX

3

z

o

<

u.

a

u

z
<

-i
li

k

CD

u.

-I

m

CO

r-
H
O
O
CO

I
x

LI

X

u

X

<

z
<
a

x

CO

>

u

-J
r-
Z

X

nnual i

1

°re cipitation

I

-

/
/
— /—
-/

1^***

--C

1

I

%

:i k

-

\

\

\

^^

***"^^i

*

3

If^

•'•J

\
\

: r^

•*

•

\

N
\

•
•
•
•
•

•

•
•

v ••"

-\— V

\ ^

\

— i

•
•

•
•

- •
•

•

\
\ \

9

t

:#
:/

\

> •

\

.*

.7

-

•
•
•

N

•

t

e

Crop Yields^

X

\

J

i

«N^~

-

r*;

-

I

I

ui

I

z

z

O

o

CD

r-
co

Z

z

_l

—

-J

CO

£

CO

<

Fig. 48. — Diagram summarizing the relations between the ranks of each of 1C northern Great Plains field stations, based upon annual precipitation, ratios, and crop

yields, as shown in columns A, B, and C in Table 7. (See text, p. 76)

BUSHELS
INCHES

( Assinnibo/ne, Mont.)

GRAIN PRODUCTION PER INCH OF PRECIPITATIO

M

RA'i

'/OS

V

V An

nual Precipiti
(Bu. per incf

Ttion
)

s

easonal Precif.
[Bu. per in

citation
eh)

^

^/

*****^

N

•— .—

I9I6

I923

Fig. 49.— Diagram showing (lower portion) the composite yield ol Brain, In bushels per acre; seasonal and annual precipitation and seasonal evaporation, in Inches;
and (upper portion) the ratios of composite yield) In bu bels of grain to inches of precipitation, I il and annual. Oops and number of plats used fur

each: Winter wheat 32, sorin wheat 30, outs M, total 120; for a period of nino years, at the Assinnibolno (Mont.) field Station. (See Tables 7, 13, and 14)

BUSHELS
INCHES

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

(Wiliiston, N. Dak.)

73

6
5
t+

3
7

i 1 — ■■■I i i i i

GRAIN PRODUCTION PER INCH OF PRECIPITATION

-

RA Tl OS

/Seasonal Precipitation
, Y (Bu. per Inch)

~~~f

K. *»

NV[

\v

&■

\>- ...

— T\..

i

n.

^

• ~^ Annua/ Precipitation ' ""■••^. N,

(Bu.per/nch) j •*■*

^TtStti'

&&~*~

4-5

PRECIPITATION, EVAPORATION, AND CROP YIELDS

AV. SEASONAL
EVAPORATION

AV. CROP YIELDS
AV. ANNUAL
PRECIPI TA TION

AV. SEASONAL
PRE CI PI TAT I ON

1914-

1912

1911

Pig. 50. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches; and
(upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each: Spring
wheat 19, oats 21, total 40; for a period of 12 years, at the Wiliiston (N. Dak.) Field Station. (See Tables 7, 13, and 14)

Table 5. — Mean annual and seasonal precipitation, seasonal
evaporation, and crop yields, arranged, respectively, in order of
their magnitude for 23 field stations in the Great Plains area

SOUTHERN GROUP

Annual precipita-
tion (inches)

Lawton 28.51

Woodward.. 25.37
Garden City 19. 01

Amarillo 18.76

Tucumcari.. 18. 71

Dalhart 18.68

Big Spring.. 17.80

Average— 20. E

Seasonal precipita-
tion (inches)

Woodward.. 17.60

Lawton 17.45

Dalhart 14.43

Amarillo 14.20

Garden City 14. 26
Tucumcari— 13.97
Big Spring— 12. 06

Seasonal evapora-
tion (inches)

Big Spring- 58. 372
Tucumcari- 54. 635
Garden City 52.152
Amarillo— 52.082

Dalhart 51. 828

Woodward- 49. 680
Lawton 43.308

Average— 14. 85 Average— 51. 722

Composite acre
crop yields (bushels)

NORTHERN GROUP

Hays 21.59

Colby 20.29

North Platte 20. 02

Akron 17.81

Moccasin 17.11

Edgeley 17.01

Ardmore 16.69

Dickinson— 16.05

Mandan 15.88

Bellefourche 15.80
Scottsblufl- 15.06

Archer 14.81

Sheridan 14.79

Huntley 14.76

Wiliiston— 14.68
Assinniboine 12. 36

Average... 16. 54

Grand

average- 17.89

Hays 11.77

North Platte 11.36

Colby 11.11

Ardmore..-- 10.84

Edgeley 10.51

Mandan 10.13

Akron 9.71

Dickinson.. . 9. 55
Bellefourche 9. 07
Moccasin- _ - 8. 88
Scottsbluff- 8.43

Sheridan 7.99

Archer 7.86

Wiliiston 7. 74

Huntley 7.54

Assinniboine 6. 99

Average— 9. 34

Grand
average - 11.02

Hays 46.562

Akron 43.116

North Platte 41.955

Colby 39.819

Scottsblufl- 37.391
Ardmore... 36.919

Archer 36.897

Bellefourche 36.543
Assinniboine 35. 214
Sheridan— 34.212
Mandan ... 34.211
Moccasin. _ 33.348
Wiliiston— 33. 103
Dickinson- 32. 516
Huntley. __ 32.497
Edgeley— 29.482

Average- 36.487

G rand
average. 41. 123

Dickinson 19.6

Colby 19.2

Mandan- 19.1

Sheridan 18.8

Huntley 18.6

Hays 18.2

Moccasin 17.7

Edgeley 17.2

WiDiston 17.0

Bellefourche.- 16.9

Ardmore 16.3

North Platte- 15. 0
Assinniboine— 12. 1

Scottsblufl 11.6

Akron.- 10.8

Archer... 9.6

Average 16. 1

Grand aver-
average.— 16. 1

In Table 5 the stations are arranged in two groups,
7 southern and 16 northern stations. It shows the
means of the annual and the seasonal precipitation
and the seasonal evaporation for all stations. It also
shows the composite crop yields for the northern group.
The crop yields for the southern group have not been
composited. This table will be found convenient for
reference, as the means of each of the four factors pre-
sented are arranged so as to be readily compared.

The number of plats of each of the three grains used
for this purpose at each station each year is shown in
Table 6. These numbers range from 40 to 133 and
average 75 each year per station, 1,199 each year for
all stations, and 15,450 for all years at all stations. It
is believed that this large number of determinations
furnishes a sound basis for comparison with the mete-
orological data gathered from observations taken at
the stations and that these comparisons will throw
some light upon many problems that have been very
obscure and concerning which many misconceptions
exist. However, it must be constantly kept in mind
that, although it seems necessary to use mathematical
expressions in the presentation, mathematical exactness
can not be expected in the conclusions. Some of the
reasons for the lack of mathematical exactness are as
follows:

(1) At some stations the number of plats averaged is
as low as 40, while at others it is as high as 133, as
shown in Table 6.

74

BUSHELS
INCHES

5
4

3

2

I

0
50

45

40

35

30

25

20

5

MISCELLANEOUS CIKCULAB 81, U. S. DEPARTMENT OF AGRICULTURE

( Huntley. Mont.]

GRAIN PRODUCTION PER INCH OF PRECIPITATION

RA T/OS

V Seasonal Precipit
~ V jf ( Bu. per inch j

ation

.^Tv X.

r 1

>,

(/^.s

>•'

"\

y ^

**••-,

' Annual Precipitation *
(Bu. per inch)

«»

--V

*******

PRECIPITATION, EVAPORATION, IRRIGATION, AND CROP YIELDS

AV. SEASONAL
EVAPORATION

1920 1922 1924 1915

1917

1914 1923 1913

1918 1912 1916 1921 1919

FlG. 51. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches,
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: Winter wheat 25, spring wheat 36, oats 34, total 95; for a period of 13 years, at the Huntley (Mont.) Field Station. (See Tables 7, 12, 13, and 14)

(2) The period during which the experiments have
been conducted at the several stations ranges from 8 to
18 years.

(3) In the grouping and regrouping of the data it
becomes necessary to use the averages of averages and
of ratios, the sums of averages, and the averages of
sums. It is obvious that mathematical exactness can
not be obtained where such sources of error exist.

(4) It is true that some of these errors might lie
eliminated by weighting the averages. But there are
many other sources of inexactness that could not be so
eliminated.

(5) It has been decided, therefore, to submit the
figures as thejr are presented in Table 7, which shows
clearly the relations in time, place, quantity, duration,
and the number of pints upon which the data lor each
station are based.

Table 7 has been prepared to show the annual precipi-
tation, the composite yields of winter wheat, spring
wheat, and oats, the ratios between precipitation in
inches and yields in bushels, and the relations between
thes< factors for each year at each of the 16 stat n-for
an aggregate period of 218 years.

Tin composite yields are computed for each station in
the equivalents of bushels of wheal. The number of
pi ni i of each of these grains al en eh station is -how n in

Table (i. The yields per acre of each crop are given in
Figures 2 to 33j inclusive, and the composite yields
computed from these data are given in Table 7.

Table 6. — Number of plats upon which wheal and oats were grown
each year at each station and for various periods at 16 stations in
the northern Great Plains area

Years

. Each

year

For ent

re period

Field stations

at
each
st a-

Wheat

Oats

Total

Wheat

Oats

Total

Win-
ter

Spring

Win-
ter

Spring

12

19

21

40

1 S)

Assinniboine...

9

32

30

58

120

288

270

52-2

1,060

17

6

-

31

102

587

lluntlev

13

25

36

■ :i

95

468

442

18

-

27

486

•i;i,

Matidan

11

67

66

133

1,463

17

28

28

176

8

23

37

50

110

184

400

ssO

Bellefourchc

17

6

30

32

68

in.'

510

1.1. V,

12

12

39

41

141

468

192

Scottsblufl

10

11

27

110

270

750

North l

18

IV

3 12

414

1,206

Archer.

11
111
11
18

13
17
41

in

30

31

..1

71
41

10

847

1, 136

Colin-..

I.M

Ml

Tot .

2 IS

251

435

813

1,190

3, 291

5. 638

0, 521

A.V61

Tin ratios between precipitation and yield- are
obtained l>\ dividing the yields expressed in bushels
pel- acre by the annual precipitation expressed in inches
per annum. These ratios also indicate the number of
bushels of grain produced for each inch of annual pre-
cipitation.

uiauii

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

75

Table 7. — Annual precipitation, bushels of grain produced for each inch of precipitation, and composite annual acre yields of wheat

and oats at 16 field stations in the northern Great Plains area

Station, number of plats, and coi

nparison

1906

1907

1908

1909

1910

1911

1912

1913

1914

1915

1916

1917

1918

1919

1920

1921

1922

1923

1924

Means

Rani

factors

A

B

C

Assinniboine, 120 plats:

Precipitation .

20.01
2.25
45.0

18.44

1.78

32.8

12.53
1.21
15.2

7.70
.78
6.0

12.47

.73

9.1

15.13

.86

13.0

13.95
.69
9.6

17.74

.81

14.4

15.30
.76
11.7

13.74
.52
7.1

11.58
1.20
13.9

11.88
.86
10.2

15.20
.52
7.9

13.72

.74

10.2

17.88
.37
6.6

17.92

.64

11.5

16.49
.23
3.8

12.10
0
0

11.97
.47
5.6

14.05

.64

8.8

16

11.98
.52
6.2

1L49
.30
3.5

14.06

.92

13.0

14.48
2.02
29.2

16.96
1.04
17.7

13.63
.68
9.3

14.42
1.08
15.6

12.10
1.04
12.6

10.53
.54
5.7

19.42

1.54

29.9

11.24
1.04
11.7

18.09
1.07
19.3

14.16
.13
1.9

17.75
. 32
5! 6

20.09

.85

17.0

24.15
.59
14.3

15.28
.85
13. 3

16

9.40
.26
2.4

16.34
.20
3.3

8.32
.22
1.8

9.71
.10
1.0

11.77
.14
1.6

12.50
.19
2.4

14.99
.09
1.3

13.75
.84
11.6

10.35
.22
2.3

16.22
.81
13.1

19.12
.32
6.1

10.26
.22
2.3

21.99

.44

9.6

24.59

.76

18.8

23.36

1.29

30.1

26.53

.59

15.7

10.78
.89
9.6

14.58

.75

11.0

20.51

.87

17.8

14.60
1.77
25.9

20.86
.26
5.4

18.44

.85

15.7

28.08

.85

23.8

12.89
.47
6.0

12.71
1.52
19.3

18.52

1.49

27.6

13.38
1.41
18.9

19.72

.67

13.2

22.48
.86
19.3

21.58
1.02
22.1

22.39

1.41

31.5

18.52

1.69

31.3

13.35

.76

10.2

10.80
.50
5.4

14.86

.79

11.8

12.38

.96

11.9

12.36

.86

12.1

14.68
1.07
17.0

14.76

1.18

18.fr

14.79
1.19
18.8

14.81
.63
9.6

15.06

.76

11.7

15.80

.97

16.9

15.88
1.14
19.1

16.05

1.19

19.6-

16.69

.90

16.3

17.01
1.00
17.2

17.11
1.02

17.5

17.81

.56

10.8

20.02

.70

14.7

20.29

.92

19.2

21.59

.84

18.2'

16

-.11

Yield

13

Williston, 40 plats:

Precipitation -.-

inches..

14.72
2.10
30.9

10.02
.18
1.8

10.01
.52
5.2

20.29
1.65
33.4

13.17
.40
5.3

13.79
1.28
17.7

14.15
1.76
24.9

21.00

1.53

32.2

14.30
2.01
28.7

13.06

1.79

23.4

17.08

2.24

38.2

15

5

Yield

..bushels..

q

Huntley, 95 plats:

._ inches..

11.58
.87
10.1

11.23
.55
6.2

11.59
.87
10.1

11.75
.61
7.2

13.31
.46
6.1

14.83
.15
2.2

14.47
.39
5.6

14.09
1.37
19.3

18.33

.81

14.8

14.29

.76

10.8

14.97

.46

6.9

15.92

.80

12.8

23.85
1.00
23.9

26. 03
1.25
32.6

18.56
1.44
26.8

16.30
1.62
26.4

11.25
.17
1.9

14.17

.99

14.0

16.77
1.28
21.4

14.68

.68

10.0

18.20

1.53

27.9

21.25

1.46

31.0

15.85

.71

11.2

14

3

Yield . -

..bushels..

5

Sheridan, 110 plats:

13

2

Yield ---

..bushels..

4

Archer, 77 plats:

Precipitation -

14.80
.49
7.3

15.09

.83

12.5

13.08
1.05
13.7

23.79

1.76

41.9

23.51
.57
13.3

14.36
0
0

24.67

.84

20.7

16.78

1.30

21.8

18.75

1.13

21.1

16.27
.35
5.7

20.84

.54

11.2

19.67

1.06

20.8

15.50

1.46

22.6

15.78

1.51

23.8

21.14
2.60
54.9

23.97

1.53

36.6

19.21
2.26
43.4

26.82
1.47
39.3

18.94

2.04

38.6

17.94

1.93

34.6

22.81
1.25
28.4

33.33

.99

33.0

25.84

.97

25.1

30. 53

.56

17.2

21.57

1.61

32.8

14

11.90
.33
3.9

17.01
.36
6.1

13.13
1.20
15.8

15.47
1.65
25.5

18.54
1.62
30.1

18.24
1.27
23.1

22.32

.47

10.4

18.83

.95

17.8

14.83
.54
8.0

17.07

1.27

21.6

16.41

1.34

22.0

19. 00

1.74

33.2

16.92
1.20
20.7

15

12

15

..bushels..

lfi

Scottsbluff, 75 plats:

Precipitation

...inches..

15.82
1.02
16.2

13.57

.15

2.0

15.27
.77
11.7

14.45

.97

14.0

11

13

Yield

..bushels..

14

Bellefourche, 68 plats:

Precipitation

inches .

13.52
1.33
18.0

17.62
1.68
29.6

12.51
.22
2.8

6.62

0

0

20.55

1.57

32.2

15.99
1.53
24.4

19.84

1.73

34.3

15. 79
0
0

17.12
1.13
19.3

15.41

1.51

23.2

16.84
.34
5.8

20.27
.38
7.8

18.62

1.21

22.5

21.52

1.28

27.6

17.06
1.03
18.4

14

17.00
1.57
26.7

15.68
.75
11.8

17.95

1.19

21.3

16. 49

1.53

25.2

20.76

1.16

24.0

14.70

1.63

23.9

16.55

1.66

27.4

13.94
.62
8.6

10

8

Yield

..bushels..

in

Mandan, 133 plats:

Precipitation

___inches._

9

4

Yield

..bushels..

3

Dickinson, 52 plats:

Precipitation

inches. .

bushels..

...inches..

.:..:

15.17

1.73

26.2

16.32

1.70

27.8

18.97
1.82
34.6

19.13

.99

19.0

10.70
.46
4.9

20.58
0
0

12.55
2.16
27.1

11.19
.13
1.4

15.63

1.35

21.1

15.28

1.88

28.8

14.94
.30

4.5

17.88

.25

4.4

8

7

Ratio

Yield

Ardmore, 92 plats:

Precipitation

1

....

10

Yield

..bushels.

11

Edgeley, 56 plats:

Precipitation

inches..

18.58

1.66

30.8

12.77

.88

11.3

16.13

.69

11.1

14.99
.48
7.2

16.72

1.67

27.9

22.18

1.67

37.1

21.36
.55
11.8

23.27

.65

15.2

11.16

.44

4.9

18.11

13^9

17.12

.54

9.2

12.18
.58
7.1

14.79
.14
2.1

17.02

1.46

24.9

15.72

.18

2.9

13.68
0
0

24.62
1.30
31.9

22.31
.14
3.2

21.62

1.11

23.9

20.89
.35
7.4

6
5

7

Yield

Moccasin, 62 plats:

Precipitation

Ratio

bushels.
...inches__

18.33
1.09
19.9

16.86
.33
5.5

24.48

.97

23.8

21.96
.25
5.5

14.44
0
0

13.46

1.02

13.7

12.62
.21
2.6

17.18

1.57

27.0

17.68

1.26

22.3

22.38

1.86

41.7

8

6

Yield

bushels
. inches .

7

Akron, 71 plats:

Precipitation

4

16

Yield

..bushels

16

North Platte, 67 plats:

Precipitation...

inches_ .

bushels. .

. _inches_.

:::::

25.94
.72
18.7

21.62

1.35

29.2

3

Ratio

Yield

14

"n

Colby, 41 plats:

Precipitation ..

2

Ratio .

9

Yield

.bushels .

■J*

Hays, 40 plats:

Precipitation

inches..

—

27.00

.43

11.7

22.79

.90

20.6

26.81
JO
0

20.92

1.55

32.5

15.14

.66

11.4

8

14.04
.08
1.3

20. 9.r

.69

14.5

19.38

.68

13.8

10

21.30
.33
7.1

15.13
1.02
14.8

11

1

12

Yield

bushels. _

inches..

bushels..

6

Average:
Precipitation

18.58

1.66

30.8

1

20.22

.94

17.0

t

17. 5fi
1.07
19.0

6

20.21

1.27

23.4

8

12.8:
.3f
5.2

18.35

.96

17.9

14

15.58
.42
7.7

16

18.13
1.05
18.7

16

15.31
.74
11.9

15

17.20

.88

15.1

13

16.69

1.20

21.0

13

16.54
.93
16.1

Ratio. _..

Yield.... ____--___.

Number of stations for each year '

1 218 station years.

The number of years that these investigations have
been conducted at each of the stations can be seen at a
glance.

Only those stations having corresponding periods of
the same years are mathematically comparable. But
for the purpose of obtaining a rough approximation of
the relations between the annual precipitation and
crop yields it has seemed best to give the simple facts
as shown by the records. Moreover, it is believed that
any attempt to weight the averages from the several sta-
tions so as to make them more nearly comparable would
result in no closer approximation to the truth than can
be had by using the figures as they appear in Table 7.

Comparisons of the relations between precipitation
and crop yields for the several years at any one station
are not subject to the complications above mentioned.
The stations, therefore, have been treated individually

in the figures and tables that follow, and it is believed
that these data are by far the most reliable of any now
available bearing upon the relations between annual
precipitation and crop yields.

There are some distinct advantages to be gained,
however, by using the results from the entire period of
218 crop years at the 16 northern stations and making
comparisons between the individual crop years regard-
less of the station at which the results were obtained;
and also by comparing the means of the results obtained
at each of the 16 stations with those obtained at all of
the other stations. In making such comparisons it
must be borne in mind, for the reasons already explained,
that these results are not strictly comparable from a
mathematical standpoint. Such comparisons never-
theless serve a useful purpose by showing the relations
between crop }delds and precipitation.

76

BUSHELS
INCHES

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
(Sheridan, Wyo.)

1924

1923

1919

Fig. 52. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: Winter wheat 23, spring wheat 37, oats 50, total 110; for a period of eight years, at the Sheridan (Wyo.) Field Station. (See Tables 7, 13, and 14)

It will be noted that the relative rank of the several
stations for precipitation, ratios, and crop yields are
given in the last three columns of Table 7, indicated
as A, B, and C, respectively. The means of each of
these factors, annual precipitation, ratios, and crop
yields, are given in the column headed "Means."

In column A are given the ranks based on precipita-
tion. As the stations were arbitrarily arranged in the
inverse order of the magnitude of the annual precipita-
tion, the ranks based on this factor* appear in regular
sequence from the bottom toward the top of the table.
In column B are given the ranks based on the ratios
and in column C the ranks based on crop yields.

If the relations between annual precipitation and
crop yields were directly proportional, the relative
ranks of crop yields would be the same as those of the
annual precipitation, and the ratios would be constant
for all crop years; but nothing even remotely approach-
ing such an arrangement exists.

Of course, perfect regularity can not be expected, as
it is well known that there are always present some
inhibiting factors that will disturb perfect equilibrium;
hut where so little semblance of orderly arrangement
exists it seems certain that the inhihiting factors have
eliminated the effects of any directly proportional rela-
tionship that might have existed between annual pre-
cipitation and crop yields (fig. 48).

There is another method of comparison that might
help to interpret the facts set forth in this table.

As the stations are arranged in the order of increas-
ing magnitude of annual precipitation, it is ohvious

that the first 8 stations would show an average annual
precipitation lower than the second 8 stations. The
first 8 have an average of 14.77 inches, the second of
18.32 inches, a difference of 3.55 inches.

The mean crop yield for the first 8 is 15.43 bushels
and for the second 16.69 bushels, a difference of 1.26
bushels. If the relations between precipitation and
crop yields were directly proportional, the differences
would be about the same, whereas the difference in
precipitation is nearly three times that of yields. The
mean ratio for the first group is 0.9S and for the second
group 0.S9, which reflects the discrepancies in the rela-
tions between precipitation and yields. This test gives
the same indications as the previous ones, which is
that the relations between precipitation and yields are
not directly proportional. Many other interesting
comparisons are made in considering the data of the
individual stations which follow.

AVERAGE YIELDS OF WHEAT AND OATS

Table 7 gives the composite yields of wheat and oats
for (Mich year for the 16 field stations. By grouping
these according to yields per acre, regardless of stations,
the facts shown in Table 8 are presented.

Two bushels of oats are computed as approximately
equivalent to one bushel of wheat. At 10 stations
winter wheat, spring wheat, and oats arc used for
computing the composite yields. This is done by
taking one-fourth of the sum of the yields in hushels of
these three crops. At four of the stations, Williston,
Dickinson, Mandun, and Edgeley, spring wheat and

CEOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

(Archer, Wyo.)

77

PRECIPITATION, EVAPORATION, AND CROP YIELDS

^■Seasonal Evaporation

1917 1918 1924 1915 1914- 1923 1916 1919 1921 1922

Fig. 53. — Diagram showing flower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each:
Winter wheat 13, spring wheat 30, oats 34, total 77; for a period of 11 years, at the Archer (Wyo.) Field Station. (See Tables 7, 13, and 14)

BUSHELS
INCHES

( Scoff sb/uff, Neb.)

GRAIN PRODUCTION PER INCH OF PRECIPITATION

■

RATI OS

/Seasonal Preci pi fat/on
/ (Bu. per Inch)

,»*•' ' * "»m_L_

t

.^-^ r*o-

'— -•.^ *"|" t***^\Annua/ Prec/pifation"'-—— •—•—•— •■—• — *~V— •—■ •— •^£t^»*»— ^
•"*■»•"""" . (Bu. per Inch) 1 ***•"•.,

-.— •-""""*"

50
4-5
40
35
30
25
20
I 5
I 0
5

PRECIPITATION, EVAPORATION, IRRIGATION, AND CROP YIELDS

AV. SEASONAL
EVAPORATION

AVERAGE ANN UAL
PRECIPITA TION
AV CROPYIELOS

AV. SEASONAL
PRECIPITA TION

1920

1916

1912

1915

1917

1913

1914

1918

1919

1921

Fig. 54. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each:
Winter wheat 11, spring wheat 27, oats 37, total 75; for a period of ten years, at the Scottsblufl (Nebr.) Field Station. (See Tables 7, 12, 13, and 14)

78

MISCELLANEOUS CIRCULAR 81, U. B. DEPARTMENT OF AGRICULTURE

(Bellefoarche. S.Dak.)

1920 '15 '24- '22 '09 '23 "19 '13 '18 '17 '12 '08 '21

I I

Fig. 55. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: Winter wheat 6, spring wheat 30, oats 32, total 68; for a period of 17 years, at the Bellefourcho (S. Dak.) Field Station. (.See Tables 7, 12, 13, and 14)

oats only are used. The sum of the yields in bushels
of these two crops is divided by 3 to obtain the com-
posite yield. At Colby and Hays the actual yields in
bushels of winter wheat only are used, neither spring
wheat nor oats being well adapted to these locations.
Average yields per acre calculated from 15,450 deter-
minations covering 218 crop years arc equivalent to
16.1 bushels of wheat per acre. (Table 7.)

It is generally believed by practical farmers that a
crop of wheat yielding less than 10 bushels per acre is
produced at a loss, but that higher yields may re-
present a profit if prices and production costs are
normal. This division into two groups, representing
unprofitable and profitable crops, is therefore of much
interest to the practical farmer.

It will be seen from Table 9 that, taking the 16 sta-
tions collectively, 66 per cent of the 218 crop years
are classed as profitable and 34 per cent as unprofitable.
Expressed in other terms, about two years out of three
were profitable and one year unprofitable. Ii ia
believed that this is a fair estimate of what may be
expected throughout the northern dual Plains,
extending as far south as central Kansas.

Mm \Jien the stations are considered individually
it i- seen thai there is a wide departure from this ratio.

The station at Assinniboine, Mont., has a record of
only nine years. For five of the nine years the annual
precipitation was below normal and averaged only
10.5 inches. Two other years averaged 14.10 inches,
but the crop year 1916 had 20.01 inches of annual
precipitation. These adverse climatic conditions re-
sulted in the production of but four crop yields above
10 bushels per acre and five below, or a ratio of 56 per
cent below and 44 per cent above.

Table S. — Average composite yields of winter wheat, spring wheat,
and oats grown by all methods for 918 crop years at IB fix Id stations
in the northern Great Blaine area

Acre-yield data compared

1 Jure

Yields up i" 5 bushels, Inclusive

I ind up to id bushels, Inclush e

More than 10 and up ta IS bushels, Inclusive..

nd up to 20 bushels, inclusive
More than 20 and up to 25 bushels, Inclusive
I ■ nd up to -<n i'ii ihcls, Ini

0 ind up to 35 bushels, Inclu \\ i
ind up to 40 bushels, Ini Ii
\lore LbaniOandui bushi Is, Inclusive

S ia I inn years

Propor-

her

tion (pi i
cent

a

28

12 -'.

39

17.89

10

ia i

11.01

12.89

23

in ;.;,

l'i

S :i

;,

2, 29

-

100

im*M

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA
(Mandan, N. Dak. )

79

4-5
40
35
30
25

! PRECIPITATION, EVAPORATION, AND CROP YIELDS

AV. SEASONAL
EVAPORATION

1915

1914-

1922

1923

J9I6

1921

1924

1919

1920

1918

1917

Fig. 56.— Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each:
Spring wheat 67, oats 66, total 133; for a period of 11 years, at the Mandan (N. Dak.) Field Station, (See Tables 7, 13, and 14)

The station showing the lowest percentage of years
when the yields fell below 10 bushels per acre is Hunt-
ley, Mont. This station has a record of 13 years. In
only two of these years have the crop yields been below
10 bushels per acre, and in 11 years they have been
above, or a ratio of 15 per cent below and 85 per cent
above.

These two stations are both in Montana, about 200
miles apart. The altitude of Assinniboine is about
2,500 feet and that of Huntley 3,000 feet. The soil
of the Assinniboine station is as well adapted to dry
farming as that at Huntley, if not better. The general
climatic conditions of the two stations are very similar.
The annual precipitation at Huntley averaged 14.76
inches for the 13-year period and that at Assinniboine
12.36 inches for the 9-year period. But the average
annual precipitation at Assinniboine for the 4-year
period from August 1, 1911, to July 30, 1915, was 14.78
inches, and at Huntley it was 14.68. From these facts
it seems probable that if the investigations at Assinni-
boine had been started in 1911, when they were at
Huntley, there would have been no such differences in
the results obtained at these two stations. Many
other such comparisons might be made to account for
the differences in the results from the individual sta-
tions.

Tables 10 and 11 are arranged on the same general
plan as Table 9, except that the crop yields have been
divided into 10 classes instead of 2 and that the
numbers of crop years are used in Table 10 and the
percentages of crop years in Table 11. The average

crop yields also have been given in both Tables 10
and 11 and the average annual precipitation for each
station has been given in Table 11, in order to facilitate
comparisons.

Table 9. — Comparison of composite small-grain acre yields below
and above 10 bushels per acre, by station years, at 16 field stations
in the northern Great Plains area

Station years with yields of—

Location

10 bushels or less

More than 10 bush-
els

Total

Number

Propor-
tion (per
cent)

Number

Propor-
tion (per
cent)

Williston. .

5
5
4
2
5
2
3
3
6
5
4
8
6
10
2
5

42
56
24
15
28
18
18
38
35
42
40
44
55
62
18
28

7
4

13

11

13
9

14
5

11
7
6

10
5
6
9

13

58
44
76
85
72
82
82
62
65
58
60
56
45
38
82
72

12

9

Moccasin

17

13

Dickinson..

18

Mandan. _ ._

11

Edgeley..

17

8

17

12

Seottsbluff

10

North Platte..

18

Archer

11

Akron

16

Colby

11

"Hays

18

Total _

75

34

143

66

218

It is believed that Tables 9, 10, and 11 are well worth
careful study even if for no other purpose than to show
the danger of making broad generalizations from in-
adequate data.

80

BUSHELS
INCHES

6
5
4-
3

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

(Dickinson, At. Dak.)

GRAIN PRODUCTION PER INCH OF PRECIPITATION

i

RAT /OS

•Seasonal Precipitation 4

, ( Bu. per inch) \ /

Annual Precipitation

( Bu. per inch)

t\ -*-•**

|%

f ***■ *

J *'

•v y-. 1 "v»

1

J*

^

•

d •

^

*^1^

\ \

Jf A

\ X

X

I /

J*

V

1 *-•*

1914 '12 '22 '15

Fig. 57. — Diagram showing Oower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches; and
(upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each: Spring
wheat 25, oats 27, total 52; for a period of 18 years, at the Dickinson (N. Dak.) Field Station. (See Tables 7, 13, and 14)

Table 10. — Distribution of crop yields, by station years, at 16 field stations in the northern Great Plains area

Number of years with respective acre yields

Average

Field stations

Total
failure

0to5
bushels

5 to 10
bushels

10 to 15
bushels

15 to 20

bushels

20 to 25
bushels

25 to 30

bushels

30 to 35

bushels

35 to 40

bushels

40 to 55

bushels

Total

yields
(bushels)

3
1
2
1
2
1
2
1
3
1
1
2
3
4

2
4
2
1
2
1
1
2
2
2
3
6
3
c
1

2

1
3

4
4
2
4
6

1

1

4

12
9
17
13
IS
11
17
8
17
12
10
18
11
16
11
18

17.0

1

12.1

3
2

2

3

1
1
2
2
1
2
1
1
3
1
2
4
2

1
3
4
1
1
3
2
3

1

1

1

17.5

18.2-

1

3

1
1

19.6

1

1

19. 1

2

2

1
1

17.2

18.8

1

2

2
1
3
1
3
2
1
3

3

1
2
3
1
1
1
2

1

16.9

1

16.3

Scottsblufl

11.7

North Platte

1

2

1

14.7

9.6

1
1

1

10.8

Colby

1
2

2
4

19.2

1

1

18.2

B

3.67

28
12.85

39
17.89

40
18.35

24
11.01

27
12.39

23
10.55

19
;.. 71

5
2.29

5
2.29

218
100.00

16.1

These considerations furnish just a little more weight
to the steadily increasing evidence indicating thai the
annual rainfall is a very poor index to the crop yields
in a region like the northern Great Plains, where the
normal rainfall ranges from 15 to 20 inches per annum,
and thai it will never be possihle to make an agri-
cultural classification of this region on the basis of
meteorological information. A knowledge of the
climatic conditions throughout the United States is
undoubtedly of inestimable value to the farmers of the
entire country, and the daily weather reports and storm

and frost warnings can not be too highly estimated as
assisting farmers in their farm operations. But the
agricultural possibilities of any given locality or farm
can be determined in only one way, and that is by the
experience of practical fanners.

RESULTS UNDER IRRIGATION AT HUNTLEY. BELLEFOURCHE. AND
SCOTTSBLUFF

At three of the field stations -lluntlev, Bellefourche,
and ScottsblufF — the Office of Western Irrigation Agri-
culture of the Bureau of Plant Industry is conducting

BUSHELS
INCHES

CHOP YIELDS AND PKECIPITATION IN THE GEEAT PLAINS AREA
( Ardmore, S.Dak.)

81

GRAIN PRODUCTION PER INCH OF PRECIPITATION

RA T/OS

^Seasonal Precipitation .
' lu. per inch)

Annual Precipita
( Bu. per inch)

' L

Fig. 58. — Diagram showing (lower portion) the composite yield of grain, in bushels Per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: Winter wheat 12, spring wheat 39, oats 41, total 92; for a period of 12 years, at the Ardmore (S. Dak.) Field Station. (See Tables 7, 13, and 14)

Table 11. — Distribution of small-grain crop yields reduced to percentages of the total number of station years at 16 field stations in the

northern Great Plains area

Percentage of years with respective

acre yields

Total
crop
years

Average annual

Field station

Total
failure

0to5
bushels

5 to 10
bushels

10 to 15
bushels

15 to 20
bushels

20 to 25
bushels

25 to 30
bushels

30 to 35
bushels

35 to 40
bushels

40 to 55
bushels

Acre

yields

(bushels)

Precipi-
tation
(inches) ]

Williston

25.00
11.11
11.76

7.69
11.11

9.09
11.76
12.50
17.65

8.33
10.00
11.11
27.27
25.00

16.67
44.45
11.76

7.69
11.11

9.09

5.88
25.00
11.76
16.67
30.00
27.77
27.27
37.50

9.09
11.11

8.33
33.33
23.54
30.77
11.11
36.36
35.30

8.33

8.34

33.33

12
9
17
13
18
11
17
8
17
12
10
18
11
16
11
18

17.0
12.1
17.5
18.2
19.6
19.1
17.2
18.8
16.9
16.3
11.7
14.7
9.6
10.8
19.2
18.2

14.68

11.11

12.36

17.65
15.39
11.11

17.65
7.69
5.56
18.18
11.77
12.50
11.76
8.33
10.00
16.66
9.10
12.50
36.36
11.11

5.88
23.08
22.22
9.09
5.88
37.50
11.77
25.00

5.88

5.88
7.69

17.11

14.76

5.56

16.67

5.55
9.10

16.05

9.09
5.88

15.88

Edgeley

11.76

11.77
12.50
5.88

17.01

14.79

5.88
16.67

11.77
8.33

30.00
5.56

27.27

12.50
9.09

16.67

17.65
8.33

20.00

16.67
9.09
6.25
9.09

11. 11

5.88

15.80

8.34

16.69

Scottsbluff--.

15.06

North Platte .

5.56

11.11

5.56

20.02

14.81

6.25
9.09
5.56

17.81

Colby

9.09
11.11

18.19
22.22

20.29

Hays

5.56

5.55

21.59

218

16.1

16.54

investigations with the same crops as those used in these
investigations. That office has kindly consented to
allow the use of some of its results. The periods of
time covered by these two lines of investigations did
not correspond entirely; the number of plats used for
each of the three grains was not so great as in the dry-
land investigations, and there were other factors which
make any precise comparison of them with the dry-land
yields of doubtful value. But the results are given in
Table 12, and they are shown in Figures 51, 54, and 55

11810°— 27 6

for these three stations by the line marked "Irrigation."
They have little significance except to show that irri-
gation farming is by no means exempt from the influence
of inhibiting factors and that yields are nearly as erratic
under irrigation as in dry farming.

At Huntley the yields under irrigation are consist-
ently higher except for the year 1915 when they were
slightly exceeded by the dry-land yields. They were
fairly uniform, ranging from about 27 bushels to about
40 bushels per acre.

82

BUSHELS
INCHES

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

( Edge ley, N. Dak.)

6
5

GRAIN PRODUCTION PER INCH OF PRECIPITATION

/?/? 77 OS

3
2

^****j\

Seasonal Precipitation

/ (Bu. per Inch) 1

■

//

•>Vv

[^

i

0-

.**

VN

Br ^*"— Annual Precipitation
| (Bu.perlnch)

>

.'

^* •«^.--»-

^;

45
40
35
30
25
20
15
I 0
5

PRECIPITATION, EVAPORATION, AND CROP YIELDS

Seasonal Precipitation — Vf-/ -

III V

AV. SEASONAL
EVAPORATION

AV. CROP YEAR

AV. ANNUAL
PPCCIPITA TION
AV. SEASONAL
PRECIPITATION

1914 '12 '16 '19 '15 '06 '21 '22 '09 '08 '13

'II

77 '20 '07 '18 '10

Fig. 59. — Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: SDring wheat 28, oats 28, total 56; for a period of 17 years, at the Edgeley (N. Dak.) Field Station. (See Tables 7, 13, and 14)

BUSHELS
INCHES

(Moccasin, Mont. )

GRAIN PRODUCTION PER INCH OF PRECIPITATION

45
40
35
30
25
20
I 5

PRECIPITATION.'eVAPORATION, AND CROP YIELDS

1912 '09 '20 *I6 '23 '10 '18 '15 '17 'II "14 '22 '13 '08 '21 '24 *I9

i howlng (lower portion) the compo Ite yield "f grain. In bushels pi i I inual precipitation and seasonal evaporation, In Inches;

and (upper portion) the ratios of a eld In bu be! ol pltation, bol mual. Crops and number of plats used for

each: winter wheat 8, spring whi il 2 5, oats II, total 62; for a period of 17 years, al the Moccasin (Mont J Field Station. (See I abli • 7, 13, and M)

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

(Akron, Colo.)

83

1915 '20 '19 '12 '09 '14 '17 '10 '23 '22 'II '21 '13 '16 '18 '24

Fig. 61.— Diagram showing (lower portion) the composite yield of grain , in bushels per acre; seasonal and annual precipitation and seasonal evaporation in inches;
and (upper portion) the ratios of composite yields in bushelsof grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each- Winter wheat 17, spring wheat 23, oats 31, total 71; for a period of 16 years, at the Aaron (Colo.) Field Station, (bee Tables 7, 13, and 14)

At Bellefourche the irrigation yields are far less
uniform or consistent than at Huntley. They range
from 10 to nearly 35 bushels and are about as erratic,
from year to year, as are the dry-land yields. They are
lower than the dry-land yields in 5 out of 13 years.
The dry-land yields in 1915 were about 55 bushels,
while those under irrigation were only about 35 bushels.

Table 12. — Composite yields of winter wheat, spring wheat, and
oats under irrigation at Huntley, Bellefourche, and Scottsbluff
field stations

Acre yields (bushels)

Year

Acre yields (bushels)

Year

Huntley

Belle-
fourche

Scotts-
blufl

Huntley

Belle-
fourche

Scotts-
bluff

1912

24.7
17.5
33.0
34.9
20.0
26.3
29.9

46.1
35.8
30.5
14.0
20.3
32.7
28.8

1919

1920
1921
1922
1923
1924

26.7

30.0
29.6
38.5
34.0
35.8

17.1
10.2
16.0
19.7
18.3
20.8

19.4

1913
1914
1915

37.1
40.8
37.2
34.9
33.8
38.2

23.8
17.5

1916

1917

1918

At Scottsbluff the irrigation yields ranged from about
14 to 46 bushels. In only one year, 1915, did the irri-
gation yields fall below dry-land yields. They were
more erratic than at Huntley, but not quite so much so
as at Bellefourche.

RELATIONS BETWEEN CROP YIELDS AND EVAPORATION

Although evaporation data are included for all
stations and have been included in most of the diagrams,

this factor has not heretofore entered into the discus-
sions. The reason for this omission is that the Weather
Bureau has not given the subject of evaporation much
attention and has no evaporation data comparable
with its data upon other meteorological factors for its
observation stations. If as much information were
available concerning evaporation throughout the United
States as there is concerning precipitation, it might be
of greater value in estimating the crop-producing
possibilities of different regions than is the annual
precipitation; for evaporation is an integration of
several other important meteorological factors, such as
precipitation, temperature, wind velocity, and relative
humidity. Table 13 gives the seasonal evaporation for
the 16 northern field stations, shown graphically in
Figures 49 to 66, inclusive. These data were obtained
by making daily measurements of the evaporation from
the surface of the water contained in tanks 6 feet in
diameter and 2 feet deep, sunk 20 inches in the ground.
The water level was kept at about 4 inches below the
top of the tank. The season of observation was the
six months from April to September, inclusive, each
year at each station.

RELATIONS BETWEEN CROP YIELDS AND SEASONAL
PRECIPITATION

Figures 49 to 66, inclusive, show graphically the
relations between composite yields of wheat and oats
and seasonal precipitation for the 16 stations in the
northern Great Plains. Table 14 presents these same
data in statistical form.

84

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE
Table 13. — Average seasonal evaporation at 16 field stations in the northern Great Plains area

Field stations

Num-
bei of
years

Average evaporation (inches)

1907

1908

1909

1910

1911

1912

1913

1914

1915

1916

1917

1918

1919

1920

1921

1922

1923

1924

Mean

Williston

10
9
16
13
18
11
14
8
17
12
10
18
11
16
11
18

32.586

37. 981

37.105

29.078

35. 479

32.205

3tt 454

29.940
3tt 558
35.529
34. 180
27.081
31. 277
25.562

33. 143
34.638

35. 673
31.459

36. 679
35.682
31.632
36.665
34.819
39.261
38.633
40. 578
35.349
42.709
38. 720
50.469

33.054
36. 473
29.711
32.507
32. 362
35.499
30.271
31.567
32.566
34.533
33.849
41.849
33.520
41. 422
41. 375
47.569

|

33.103
35. 214

Assinnihninp

39.980
43.186
41.425
44.629

39. 591
30.097
43.663
42.102

40. 624
42.539
40. 126
42.660
47.232
39.641
4tt 996

36.985
32.576
31.763
30.042
35.251
27.185
30. 472
28.903
33.082
34.438
36.376
33.083
40. 912
32. 721
39. 776

38.302
32.075
33.729
36.104
39.262

34.390
34.750
32. 149
31.990
33.855

32. 505
31.533
31.122
30. 072
33.536

33.097

Moccasin

32. 607
29.518

40. 135
36.158

32.242
36.441

28.770
2a 998

32. 326
31.352
33.870

32.272
31.320
31. 139
33.949
29.189

28.492
27.852
26.628
28.616
26.053

31.6891 33.348

TTimtlp.y

30.633

33.375

31.3061 32.497

29.577 32.516

29.799 34.211

Edgeley

29.927

32. 121

28.047

35.096

32. 393

25.950

29.220

29.482

Sheridan

39.238
41.998
41. 167
37.953
42.782
37.278
45.903
39.363
44.5.57

31.086
34.392
34.207

31.581
33.713
30.853

29.424
36.547
35.607

34.212

Bellefourche

40.965

36. 871

41.715

46. 701

37.744

37. 139

44. 135

37. 136

51.456

35.111
41. 777
40.428
47.441
40. 935
41.863
43. 743
47.096

27.457
28.908
33. 476
35. 4C9
30.363
33.409
31. 657
33. 277

32,482
38.870
40.277
43.603
39. 612
47.166
45.532
50.231

36.543

Ardmore...

36.919

Scottsblufi

35.183
41. 678

37. 391

North Platte

41.319

41. 936

40.423

46.564

49.702

4tt 973
37.968
44.579
42.585
47.320

34.209
34.445
41.429
37. 371
42.803

38.705
4tt 655
47.688
45. 306
48.622

41.955

36.897

Akron

42.353

43. 621

48.818

37.696

43.053

43. 116

Colby

39. 819

Hays

44.648

44.381

47.471

43. 819

59. 824

46.965

58.283

46.562

36.487

Table 14. — Seasonal precipitation and ratios of composite yields of wheat and oats produced from 1 inch of seasonal precipitation at 16

field stations in the northern Great Plains area

Field station and comparison factors

1906

1907

1908

1909

1910

1911

1912

1913

1914

1915

1916

1917

1918

1919

1920

1921

1922

1923

1924

Av-
erage

Assinniboine:

Seasonal precipitation.

12.90
3.49

9.21
3.56

6.31
2.41

3.30
1.82

4.21
2.16

7.01
1.85

5.92
1.62

8.66
1.66

9.94
1.18

7.99
.89

6.36
2.19

5.48
1.86

10.26
.77

7.54
1.35

0.71
.98

10.83
1.06

8.25
.46

8.14
0

6.94
.81

2.77
2.24

6.98
.50

5.25
2.48

8.80
3.32

11.52
1.54

10.12
.92

8.58
1.82

8.21
1.53

7.12
.80

14.08
2.12

a 58

1.36

7.63
2.53

7.02
.27

9.33
.60

5.26
3.23

11.51
1.24

3.58
.67

7.25
.46

2.21
.82

3.84

.26

4.24
.25

4.40
.55

6.22
.21

7.64
1.52

4.60
.50

9.72
1.35

13.45
.45

3.00

.77

7.61
1.26

17.15
1.10

11.45
2.63

15. 07
1.04

6.66
1.44

7.35
1.50

8.54
2.08

9.25
2.80

11.50
.47

11.54
1.36

19.37
1.23

6.83
.88

9.40
2.05

12.85
2.15

10.22
1.86

13.14
1.00

14.87
1.30

12 97
1.70

16.03
1.97

10.13
3.08

8.47
1.20

6.60
.82

11.22
1.05

7.46
1.60

6.99

1.59

Williston:

Seasonal precipitation.

8.92
3.47

5.62
.32

6.09

.85

11.91
2.80

8.83
.60

6.07
2.92

5.00
4.98

12.00
2.68

7.35
3.90

7.23
3.24

11.83
3.23

7.74

Ratio.

bushels. .

204

Huntley:

Seasonal precipitation.

inches..

7.59
1.33

7.06
.88

7.31
1.38

,6.80
1.06

7.82
.78

9.84
.23

7.50
.75

8.73
2.21

13.37
1.11

10. 13
1.07

7.44
.93

7.86
1.63

11. to
2. OS

13.27
2.46

12 63
2. 12

12.05
2.19

8.59
.22

S. 91
1.57

10.71
1.99

7.91
1.26

6.49
4.29

6.29
4.93

5.32
2.10

7.54

Ratio..

bushels..

2.44

Sheridan:

Seasonal precipitation.

inches..

7.99

Ratio

bushels.

2.25

Archer:

Seasonal precipitation.

inches..

6.55
1.11

7.70
1.62

6.74
2.03

17.15
2.44

16.54
8.80

8.24
0

13.23
1.56

9.38
2.32

10.67
1.98

9. OS
.63

11.61
.96

10.24
2.03

10.16
2.22

10.78
2.21

15.38
3.57

18.89
1.94

14.41
3.01

20.34
1.93

13.81
2.80

11.06
3.13

14.17
2.00

23.52
1.40

18.79
1.34

20.97
.82

4.64
.84

6.75
.89

8.01
1.97

8.42
3.03

11.26
2.67

9.03
2.56

12.48
.83

9.45
1.88

7.69
1.04

7.73
2.79

8.58
2.56

10.36
3.20

7.86

Ratio

bushels.. |

1.19

Scottsblufi:

Seasonal precipitation.

inches..

9.44

1.72

8.07
.25

6.86
1.71

5.68
2.46

8.43

Ratio.

bushels..

1.32

Bellefourche:

Seasonal precipitation.

inches..

7.84
2.30

12.75
2.32

5.76
.49

1.92
0

16.52
1.95

9.31
2.62

11.57
2.97

12 45
0

8.56
2.25

9.07
2.56

12.26
.47

12.93
.60

10.71
2.10

14.24
1.94

11.48
2.33

9.09
1.30

12.23
1.74

11.38
2.21

3.9S
6.03

9.72
2.46

8.44
3.25

6.00

1.4.1

9.07

Ratio

bushels..

1.80

Mandan:

Seasonal precipitation.

inches..

iai3

Ratio

bushels..

1.83

Dickinson:

Seasonal precipitation.

inches..

9.18
2.85

10.46
2.66

11. .53
3.00

8.35
2.28

6.01

.82

12.46
0

5.31
5.10

6.93

.19

9.53
2.21

9.32
3.09

6.83
.66

10.10
.44

9.55

Ratio

bushels..

2.06

Ardmore:

Seasonal precipitation.

inches..

10.84

Ratio

bushels..

1.41

Edgeley:

Seasonal precipitation.
Ratio

inches..

bushels..

inches..

14.03
2.20

6.44
1.75

9.18
1.21

10.57
.68

10.40
2.68

10.90
3.40

10.20
1.16

14.11
1.08

5.08
.97

6.50
2.14

8.87
L04

5.61
1.27

7.09
.30

7.69
3.24

6.60
.44

7.79
0

15.73
2.03

7.93
.40

12.32
1.94

8.22
.90

10.51

1.58

Moccasin:

Seasonal precipitation.

11.73
1.70

12.38
.44

18.34
1.30

15.81
.35

lass

0

6.88
1.99

5.63
.46

7.00
3.86

4.35

5.13

6.62
6.30

s ss

Ratio

bushels..

1.93

Akron:

Seasonal precipitation.
Ratio

inches..

bushels..

9.71
1.03

North Platte:

Seasonal precipitation.

inches..

10. 11
1.85

14.49
2.02

11.36

Colby:

Seasonal precipitation.

inches..

1.31
11.11

Ratio

bushels..

2.03

Hays:

Seasonal precipitation.

inches..

14.72
.80

14.03
1.47

15.37
0

9. 45
3.44

6.39
.20

9.09
1.60

12.58
.56

11. 77

Ratio

bushels..

1.72

QUANTITY OF WHEAT PRODUCED FOR EACH INCH OF RAINFALL

The data contained in Table 7 have been expressed
graphically in Figures 49 to 64, inclusive. The number
of plats used in growing each of the three grains is
given in the legends of the several diagrams. The
lower portion of each figure shows in graphic form the
annual and seasonal precipitation, the composite yields,
and the evaporation. Unlike Table 7, in which (he
respective years are arranged in chronological order,
these diagrams show the year's in (he order of (he
magnitude of their annual precipitation, the year of
highest annual precipitation being at the left and the
owest at the right.

The reader therefore has before him in these 16 dia-
grams all of the essential meteorological and crop-yield
factors necessary to enable him to see at a glance the
relations that have existed between these factors during
all of the years covered by these1 investigations at each
of the 10 stations for a period aggregating 21S years.

If the relations between annual precipitation and
crop yields were directly proportional, the ratios for all
the years at any given station would fall upon a single
Straight horizontal line across the figure. The location
of this horizontal line with reference to the scale at the
left-hand side of each figure would he determined by
the ratio between the mean annual precipitation and the

BUSHELS
INCHES

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA
{North Platte, Nebr.)

85

GRAIN PRODUCTION PER INCH OF PRECIPITATION

RA TIOS

i

seasonal Precipitation
( Bu. per inch) —

v

nnual Precipitation
(Bu per inch)

"""T\

ii*"***.

"X,

//

-<\

1

-..>•

\:

^***~*~~~~m

/

1

•*^**'

i — , '

1

L_,.,

60

1915

Fig 62 —Diagram showing (lower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite Yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each- Winter wheat 25, spring wheat 19, oats 23, total 67; for a period of 18 years, at the North Platte (Nebr.) Field Station. (See Tables 7, 13, and 14)

mean annual crop yield for that station for the entire
period of observation. The same would be true of the
ratios between seasonal precipitation and yields.

It is a well-established fact that the annual precipita-
tion is sometimes so low in the Great Plains area that
no seed is produced, and therefore there are no grain
yields. In such instances the ratio point would be
zero. When the crop yields are as low as 5 bushels per
acre, the ratio point would be expected to show a
marked depression. But such instances are not com-
mon. Yields of 5 bushels or less occurred in only 36
of the 218 years, and many, probably most, of the
instances were due wholly, or in part, to causes other
than deficient annual precipitation. We should there-
fore expect to find that departures from the horizontal
in the ratio lines would be confined to less than one-fifth
of the period of observation at each station, or from
two to four years at any station. If this were true,
we would then expect that the ratio lines beginning at
the left-hand side of each figure would extend in an
approximately horizontal direction for about four-fifths
of the distance across, and would then curve sharply
downward through the remaining one-fifth of the dis-
tance to the right-hand margin. An examination of

each of the 16 Figures 49 to 64, or of Figure 65, will
convince anyone that such is very far from being the
case. In fact, horizontal ratio lines, even between any
two adjacent points, are conspicuous by their rarity.

What is the explanation of the very erratic differences
in ratios at the same station with the same crops, in
different years, when the annual precipitation is prac-
tically the same? The obvious answer seems to be that
there are always present certain factors other than
deficient annual precipitation that inhibit directly pro-
portional relations between annual precipitation and
crop yields. Among these inhibiting factors are inop-
portune distribution of rainfall, hailstorms, high winds,
hot winds, and their concomitants, soil blowing and
breaking or beating down of crops; also diseases,
insects, and many others which are described more
in detail elsewhere.

These inhibiting factors vary widely _ in their fre-
quency, in their potency, and in the relations that they
bear to one another. Sometimes they work in con-
junction and sometimes in opposition to one another.
Sometimes beneficient influences that cause a very rapid
growth of crop plants also create an equally favorable
environment for the parasites that prey upon the crop

86

MISCELLANEOUS CLRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

BUSHELS
INCHES

t*5

35

(Co/by. Kons.)

GRAIN PRODUCTION PER INCH OF PRECIPITATION

RATIOS

Seasonal Precipitation f
( Bu. per inch) jl

X

Annual Precipitation jf
^( ' Bu. per inch) y*

. J*

1

3p-**^"r* I

PRECIPITATION, EVAPORATION, AND CROP YIELD

^._» — ""^ sWheaf and Oats

— v —

Annual Precipitation

fAV SEASONAL
EVAPORATION

AV. ANNUAL
PDCC I PITA TION

V*K CROP YIE1X

Fig. fi3.— Diagram showing flower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches i
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for
each: Winter wheat only, 41; for a period of 11 years, at the Colby (Kans.) Field Station. (See Tables 7, 13, and 14)

plants, and the damage done by the parasites may be
greater than the benefits of the favorable environment
to the crop plants. The stage of growth of the crop
plants when subjected to many of these inhibiting
factors often determines the extent of the damage done.
It is therefore generally very difficult to make any close
estimate of the damage done by any single inhibiting
factor, but it is believed that it is possible to make a
rough estimate of the net effects of all inhibiting
factors, as has been done in explaining the diagrams
\\ hich follow those now under consideration.

It seems from the evidence of these diagrams that
directly proportional relations never exist between
annual precipitation and crop yields. Such relations
arc always thrown more or less out of equilibrium by
inhibiting factors.

SI MMARY OF PRECIPITATION, CROP-YIELD, AND RATIO DATA

ure 65 presents in gra piil' fon a summary of the
otained in Figure '. inclusive. In this

cars are arranged in chronological sequ-
in accordance with Table 7. instead of in the order of
ide of the anm i ion. As onbj one

I- : was reported in 1906 and only tour stations in
M" 17, these year-, have nol been included in this dia-
gram. Each" one of the fine lines in the lower portion
"f the diagram represents a single station. The heavy

line marked "Average ratio" is the mean of all these
lines. The figures upon which this diagram is based
are presented in Table 7, with the stations they repre-
sent. The year 1908 presents but 6 stations, the years
1909, 1910, and 1911, 8 stations each; 1912, 10 stations;
1913, 11 stations; 1914 and 1915, 14 stations each;
1916, 15 stations; 1917 to 1920, inclusive, 16 stations
each; 1921, 15 stations; 1922, 14 stations; 1923 and
1924, 13 stations each. The values of I he several years,
therefore, are not strictly comparable, but this differ-
ence in weight is not sufficient to affect materially the
significant feature of the diagram, which is the intricate
maze of lines representing the ratios between crop yields
and annual precipitation owing to the absence of any-
thing approaching proportional relations between thc--o
two factors. This fact is also d< monsl n the rela-

i bhi upper part of this figure by the lines
representing crop yields and mean annual precipitation.

EU l \TIONS BETWEEN CHOP YIELDS AND SEASONAL EVAPORATION
- COMPARED WITH ANNUAL PRECIPITATION

In order to >he\\ the relations between evaporation,
crop yields, and precipitation Figure 66 is presented.
The two lines repre Ids and precipita-

tion are the same as in Figure 65. 'That representing
ratios is the "average ratio" shown in Figure 65, and
the line representing evaporation has been inverted,

BUSHELS
INCHES

65
60

55

SO

*5

40

35

30

25

20

\5

JO

5

CEOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

( Hays. Kans. )

87

GRAIN

PRODUCTION PER INCH OF

PRECIPITATION

1

RAT/OS

Seas

onal P
Bu. p

recipit
er incl

afion^ i

(

■

/N

\ Annual Precipiiation
pf ( Bu. per inch)

/TV

~-V

SsS*

A y^-^^y

'"—•-—<

'

.K

1

i i

\\

„^

PRECIPITATION, EVAPORATION, AND CROP Yl

ELDS

1915 *07

Fig. 64. — Diagram showing flower portion) the composite yield of grain, in bushels per acre; seasonal and annual precipitation and seasonal evaporation, in inches;
and (upper portion) the ratios of composite yields in bushels of grain to inches of precipitation, both seasonal and annual. Crops and number of plats used for each:
Winter wheat only, 40; for a period of 18 years, at the Hays (Kans.) Field Station: (See Tables, 7, 13, and 14)

so as to show more clearly the inverse relations between
evaporation and crop yields. These relations seem to
be somewhat closer than those between crop yields and
annual precipitation except for the year 1923, when
some inhibiting factors seem to have intervened and
reversed the normal relations. Although the subject
of evaporation and its relation to crop yield undoubt-
edly deserves further study, it seems very doubtful
whether such consideration will develop anything that
will contravene the rule that
usually dominate crop jdelds.

the inhibiting factors

REDUCTION OF YIELDS DUE TO FACTORS CTHER THAN DEFICIENT
ANNUAL PRECIPITATION

If it were possible to eliminate completely all of the
adverse factors that inhibit the full realization of the
crop-producing capacity of the soil with optimum
conditions of temperature, moisture, and physical con-
ditions for even a single year at each of the field sta-
tions, the crops produced under such ideal conditions

would provide a standard by which it would be possible
to calculate the reduction of crop yields due to factors
other than deficient annual precipitation. It is, of
course, useless to hope ever to realize any such condi-
tions; for, in the first place, the forces of nature never
have been and probably never will be completely under
the control of man. In the second place, man is woe-
fully ignorant of what constitutes such optimum con-
ditions and would not know what conditions to provide
for each crop during all of the stages of its growth and
maturity even if he had the power to do so. But
nature does occasionally provide conditions under
which crops are produced that are so much superior
to the average that they may be used as a standard of
comparison for such average crops. The year 1915
was such a year at 8 of the 16 stations — Huntley,
Archer, Scottsbluff, Bellefourche, Dickinson, Edgeley,
Moccasin, and Akron. The year 1924 was such at
North Platte and Hays, 1918 at Sheridan and Ardmore,
1916 at Assinniboine, 1909 at Williston, 1914 at Man-

88

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

BUSHELS
INCHES

55

50

45

40

35

30

25

20

15

10

5

0
3.00

2.75

2.50

2.25

2.00

1.75

1.50

1.25

1.00

.75

.50

.25

1 1 1 1 1 1 1 1 1
PRECIPITATION AND EVAPORATION AND CROP '

1

riELDS

Each point on this chart represents 820 independent determinations of

_, ■ ~, , T,W.W

' ^1 r

yif

Crop Yield

V

\

v

^

!v

/

Annua/

>

S[**^

^*v_

\

Prt

icipitotion

*u*

jr

j* ^v^^^"

^'^fc.^t

I i^-^r"

^

■*^^^-

V

1/

»^^~"

\T2^ 1/

/

S

/

>

*V

BUSHELS OF GRAIN FROM I

NCH

OF PRECIPITATION

16 STATIONS, 218 YEARS

— Each point represents the average of 4 j

72 independent determinations /

1

\ RATIOS

\

/ //

^

V^

\\y\

""" j

\ r^c

rVfokx

/' vs.

\

\Jr

1

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\w\

K\W_

A— /-

\~l~i

n't \X\I m\k

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41 \

W\ Xf-Averaqe Ratic

A\v \y . I mi

J^fSS/ \ \ 1 /\\lyfl

ijjfr^ — -/r

7— \\-

\\\ \V/\V\ /^^^Vi\^ \ >"7 / J\/>V

A V

/ \

^yXKSfScx^

v W'

JffR

//u /

if)

^^kr/vlfh

\Xl

/\ i/V

67 vc

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7y\iy$MW

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N^

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1 \

i908 1909 1910

1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924

Fig. C5. — Diagram relating to 16 field stations in the northern Great Plains area for a period of 17 years, showing (lower portion) ratios of hushels of grain to inches of
annual precipitation for each year at each field station, »«d the average of the ratios for all the stations for each year; and (upper portion) the means of the
annual precipitation, and the seasonal evaporation, in inches, and the composite crop yields, in bushels per acre, for each year. (See Tables 7, 13, and 14)

dan, and 1920 at Colby. The yields produced at
these stations and the ratios of bushels of grain to 1
inch of annual precipitation arc given in Table 15.

The data presented in Table 15 are arranged as
follows :

In section 1 is given the year showing the highest
ratio of yields to precipitation for each station with the
figure- representing the yields in hushels, the ratios of
grain in bushels to inches of rainfall, and the annual
precipitation for that year in inches.

In section 2 are given the same data concerning
yields, ratios, and precipitation, but the year for each
station is that showing the highest annual precipita-
tion, instead of the bighesl ratio, as in section 1.

In section 3 the results presented are those for years
showing the highest yields, respectively, for each
station.

Some very interesting and instructive facts are
brought out by this presentation. Among them are the
following:

(1) In 14 instances out of 16 the years giving the
highest ratio were not the years of highest precipita-
tion.

(2) In 5 instances out of 16 the years having the
highest ratio were not the years of highest yields.

(3) In 11 instances out of 16 the years having the
highest precipitation were not the years of highest
yields.

CKOP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

89

PRECIPITATION
INCHES

YIELD

BUSHELS

30

25

20

15

10

RATIOS
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
.75
.50

.25

Crop Yields I

VII

i \

J

Am

lual

1/

/y

oitation

I

mv

Evaporation
(Scale Reversed V

V

s*S J

^ i

\

fAx.

\

^7

— A

/

/

*

I v^

/
i
i
i

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\
\

\

\y

M

\

>

i

*/ \

1 *>

4
/

*

i J
/ V

*■ **
\

//

//

//

W

%/

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A

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Ratio

J*

V

V

EVAPORATION

INCHES

25

30

35

40

45

50

1908*09 '10 'II '12 '13 '14 '15 '15 '17 '18 '19 '20 '21 '22 '23 '24

Fig.

i. — Diagram showing the relations of the means of crop yields, and ratios to annual precipitation and seasonal evaporation (reversed) for a
period of 17 years at 16 field stations in the northern Great Plains. (See Tables 7 and 13)

Many other similar comparisons can be made from
the figures given in Table 15, demonstrating that
directly proportional relationships do not exist be-
tween crop yields and annual precipitation.

Table 15. — Comparisons of crop yields, ratios, and annual pre-
cipitations, by groups of the years showing the highest values for
each of these factors, at 16 field stations in the northern Great
Plains area

Field stations

Assinniboine__

Williston

Huntley _

Sheridan

Archer

Scottsbluff

Bel)efourche.__

Mandan

Dickinson

Ardmore

Edgeley

Moccasin

Akron

North Platte. _

Colby

Hays

Average...
Mean aver-

Difference

Section 1. — Years of
highest ratios

1916
1909
1915
1918
1915
1915
1915
1914
1915
1918
1915
1915
1915
1924
1920
1924

45.0
30.9
38.2
29.2
22.6
23.8
54.9
41.9
43.4
29.9
38.6
34.6
28.4
27.0
31.5
41.7

35.1
16.1

19.0

2.25
2.10
2.24
2.02
1.46
1.51
2.60
1.76
2.26
1.54
2.04
1.93
1.25
1.57
1.41
1.86

.93
.93

■a-a

20.01
14.72
17.08
14.48
15.50
15.78
21.14
23.79
19.21
19.42
18.94
17.94
22.81
17.18
22.39
22.38

18.92
16.54

2.38

Section 2.— Years of
highest precipitation

1916
1914
1920
1924
1920
1920
1920
1915
1914
1915
1914
1912
1915
1915
1915
1915

45.0
32.2
1
31.0

5.4
15.7
23.
36.6
13.3
39.3
20.7

3.2
28.4
33.0
25.1
17.2

24.2
16.1

8.1

2.25

1.53
.87

1.46
.26
.85
.85

1.53
.57

1.47
.84
.14

1.25
.99
.97
.56

.93

.09

20.01
21.00
20.51
21.25
20.86
18.44
28.08
23.97
23.51
26.82
24.67
22.31
22.81
33.33
25.84
30.53

24.00
16.54

7.46

Section 3. — Years of
highest yields

1916
1912
1915
1924
1915
1915
1915
1914
1915
1915
1915
1909
1915
1915
1920
1924

45.0
33.4
38.2
31.0
22.6
23.8
54.9
41.9
43.4
39.3
38.6
37.1
28.4
33.0
31.5
41.7

36.5
16.1
20.4

2. 25 20. 01

1. 65,20. 29
2.24117.08

1.

1.46
1.51
2.60
1.76
2.28
1.47
2.04
1.67
1.25
.99
1.41
1.86

21.25
15.50
15.78
21.14
23.79
19.21
26.82
18.94
22.18
22.81
33.33
22.39
22.38

1.74
.93
.81

21. 43

16.54

i See Table 7.

ESTIMATING THE MAGNITUDE OF INHIBITING FACTORS

As these investigations have progressed, and espe-
cially since this publication has been in preparation,
the importance of inhibiting factors has become more

apparent. Much time and effort have been devoted
to the attempt to devise a method of making some kind
of quantitative estimate of the relative magnitude of
inhibiting factors in determining crop yields. Although
it is known that these inhibiting factors are always
present, because their effects are always apparent, the
causes themselves are so elusive that it is only recently
that any method has been found that seemed to render
any assistance in estimating quantitatively the potency
of the inhibiting factors. It is only after long and
patient investigation that a method has been devel-
oped. Its limitations are fully realized, and it is for the
purpose of bringing the method to the attention of those
competent to assist in its development that it is now
presented.

In Table 15 use has been made of the highest ratios
of bushels of grain per inch of annual precipitation as a
measure of the crop-producing possibilities at the
various field stations. These are well established facts.
It is known beyond a reasonable doubt that these
numbers of bushels of grain equivalent to bushels of
wheat have been produced from each inch of annual
precipitation occurring at the respective stations.
There is nothing theoretical about it. It has been
done, not alone on a single plat but by replications
ranging from 40 to 100.

The mean average annual precipitation has been
established by meteorological observations made at
each station for periods ranging from 8 to 18 years and
averaging between 13 and 14 years. Although these
means would be more reliable if they covered a longer
period of time, they are unquestionably more trust-
worthy for this purpose than any other data now
available.

The crop yields have been observed for the same
length of time and at the same place where the meteoro-
logical observations have been made.

90

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

Three well-established groups of facts are therefore
available: (1) The mean average crop yields, (2) the
mean average annual precipitation, (3) and the ratios
between these two, at 16 field stations on the northern
Great Plains.

If, now, the mean annual precipitation for each one of
these field stations is multiplied by the respective
highest ratio of bushels of grain per inch of annual
precipitation for each one of these field stations, it will
furnish a fairly trustworthy basis for noting the actual
mean yields that have been obtained and comparing
them with the mean yields that might be produced at
these stations, respectively, if the inhibiting factors
were on an average no more potent than they have been
on one or more years in the past. These computations
have been made, and they are presented in Table 16.

Table 16. — Comparison between calculated composite yields and
mean yields actually obtained, showing the reduction due to
inhibiting factors, at each of 16 field stations in the northern
Great Plains area

[Composite yields are calculated by multiplying the mean annual precipitations by
the highest yield ratios obtained]

Field station

Assinniboine..

Will is ton

Huntley

Sheridan

Archer...

ScottsblufL...
Bellefourche..

Mandan

Dickinson

Ardmore

Edgeley

Moccasin

Akron

North Platte..

Colby..

Hays

Average

Mean
annual
precipi-
tation

Inches
12.36
14.68
14.76
14.79
14.81
15.06
15.80
15.88
16.05
16.69
17.01
17.11
17.81
20.02
20.29
21.59

16.54

Average acre yields (bushels)

Highest

ratio
obtained

2.25
2.10
2.24
2.02
1.46
1.51
2.60
1.76
2.26
1.54
2.04
1.93
1.25
1.57
1.41
1.86

1.1

Calcu-
lated

27.8
30.8
33.1
29.9
21.6
22.7
41.1
28.0
36.3
25.7
34.7
33.0
22.3
31.4
28.6
40.2

30.5

Obtained

12.1
17.0
18.2
18.8
9.6
11.7
16.9
19.1
19.6
16.3
17.2
17.5
10.8
14.7
19.2
18.2

16.1

Reduc-
tion due

to in-
hibiting

factors

15.7
13.8
14.9
11.1
12.0
11.0
24.2

8.9
16.7

9.4
17.5
15.5
11.5
16.7

9.4
22.0

14.4

It is found that the actual mean yields for the sta-
tions fall short of the calculated yields by differences
ranging from 8.9 to 24.2 bushels per acre, and averag-
ing 14.4 bushels per acre for all stations. It is believed
that 14.4 bushels per acre represents approximately
the average annual effects of inhibiting factors through-
out the entire period of the investigations for all sta-
tions; and that the figures in the right-hand column of
the table represent, approximately, the average reduc-
tion in A'ields owing to inhibiting factors for each sta-
tion, respectively.

It must be kept in mind that "the highest ratios
obtained" may be, and probably are in many in-
stances, considerably below the ratios that may be
obtained in the future if these investigations are con-
tinued. Ratios of more than 2 bushels of grain per
inch of annual precipitation have been obtained at 7
of the 16 stations. These 7 stations average a mean
annual precipitation of 15.06 inches, which is 1.4S
inches below the mean. Their ratios average 2.21
bushels of grail] per inch of annual precipitation, which
is 0.35 above the average of the highest ratios for all
stations (1.86). The mean of the annual precipitation

of the years when these highest ratios were obtained i^
17.d4 inches. This is only 1.40 inches above the mean
for ;,|| stations for all year- (10.54 inches); and all of

the stations excepl Scottsbluff have exceeded this

annual precipitation of 17.94 inches by from 2 to 15
inches in some years since the investigations began.
There seems, therefore, to be no reason for supposing
that ratios as high as any of those reported in Table 16,
or higher than they are, may not be reached at any or
all of these stations. It is simply a question of time
when a season may occur at any of these stations when
conditions are so favorable, or when inhibiting factors
are so impotent, that ratios of 2.21 or higher may be
attained at all stations.

If the inhibiting factors other than deficient annual
precipitation could be held in abeyance to the same
extent at all of the stations that they have been at seven
of them, the average yields would be 36.55 bushels per
acre, or more than twice what they have been on an
average at all these stations during the period of these
investigations. As a matter of fact, the average of the
highest yields actually produced at all the stations is
36.5 bushels of grain per acre, as shown in Table 15.
It therefore becomes obvious that crop yields on the
Great Plains are determined by inhibiting factors other
than deficient annual precipitation and that such in-
hibiting factors, on an average for all stations, have
reduced the yields from 30.5 to 16.1 bushels, or 47 per
cent, while for some stations this reduction has been
over 50 per cent. These calculations are made upon
different degrees of inhibition less than total destruc-
tion of a crop. It is obvious that when a crop is totally
destroyed, as by hail, the potency of the inhibiting
factor is 100 per cent. The lowest percentage given in
Table 16 is 32. It may therefore be stated that, so far
as our investigations show, the potency of the inhibiting
factors ranges from 32 to 100 per cent.

Attention is again called to the fact that all of this
comment concerning Table 16 is based upon differences
in degrees of inhibition of crop production by factors
other than deficient annual precipitation. If it were
possible to eliminate entirely the inhibiting factors in a
single instance, at each station, the resulting yields
would afford a standard of comparison that would show
much more impressively the dominating effects of the
inhibiting factors upon crop yields. But the evidence
contained in this table is sufficient to show that these
inhibiting factors in many instances are the dominant
factors.

Table 17 contains a rearrangement of some of the
data given in Table 7, but so grouped as to facilitate the
comparison of the composite 3*ields obtained from the
same crops grown on the same soils under the same
methods of rotation and tillage, at the same stations
and with annual precipitation the same to within 0.50
inch per annum. Opportunity is thus afforded to make
77 direct comparisons of yields with annual precipita-
tion. The ratios of bushels of grain produced for each
inch of annual precipitation and their deviations are
also given. The years during which these similar
precipitations occurred are not designated in Table 17,
but can be foiuid in Table 18.

In columns 2 and 3 the annual precipitations differing
by not more than half an inch for each station are given.
The higher precipitation i> always given in column 2
and the lower in column 3. Tin1 corresponding yields
are given in the same order in columns 5 and (> and the
ratios in columns !) and 10. The yields corresponding
to the precipitations given in column 2 are in column 5
and the ratios in column 9. The yields corresponding
to the precipitations given in column 3 are in column 6
and the ratios in column 10. Deviations in precipita-
tion are given by years in column 4; of yields by years

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

91

in column 7, and the average deviation in yields by
stations in column 8; and the deviations in ratios by
years are in column 11. The figures in column 12 refer
to the numerical designation of the several crop years
in Table 18 and Figure 67.

Table 17. — Deviations of composite yields of small-grain crops as
related to precipitation at 16 field stations in the northern Great
Plains area, arranged in the order of magnitude of station
precipitation

Field stations

Assinniboine
Wiliiston

Huntley

Sheridan

Archer

Scottsblufl...

Bellefourche -

Mandan

Dickinson.

Ardmore.

Edgeley.

Moccasin.

Akron..

North Platte.

Colby.
Hays..

Annual precipi-
tation (inches)

Corresponding crop
yields (bushels)

Deviation

Average-
Mean
average

10. 80
12.38
14.72
10.02
18.56
14.30
14.17
14.15
14.60
fll. 59
11.77
11.90
14.80
15.85
15.82
15.78
15.30
15.27
21.14
20.76
14.45
13.74
13.57
13.31
23.97
15.99
15.68
14.83
19.21
19.13
18.97
16.55
12.71
10.70
10.53
10.70
[18. 52
16.49
16.22
14.36
14.
24. 67
18.58
18.94
17.12
16.13
11.24
22.31
18.83
17.02
18.09
17.94
18.11
15.41
15.28
18.33
22.81
22.48
21.99
21.62
17.12
16.
14.97
14.94
24.59
21.62
16.49
17.88
17.18
16.27
22.39
27.00
26.81
22.79
21.52
21.30
20.95

10.78

11.

14.58

10.01

18.20

14.17

14.15

14.06

14.48

11.25

11.59

11.77

14.68

15.50

15.78

15.30

15.27

15.09

20.76

20.55

14.42

13.57

13.52

13.13

23.79

15.68

15.47

14.70

19.13

18.97

18.54

16.32

12.55

10.53

10.35

10.35

18.24

16.22

15.79

14.09

13.94

24.62

18.33

18.58

16.72

15.63

11.16

22.18

18.33

16.78

17.94

17.88

18.09

15.28

14.99

18.11

22.48

21.

21.62

21.36

16.86

16.84

14.94

14.83

24.48

21.58

16.27

17.75

17.07

15.92

21.96

26.81

26. 53

22.38

21.30

20.95

20.92

17.08 16.87

16. 97

0.02
.40
.14
.01
.36
.13
.02
.09
.12
.34
.18
.13
.12
.35
.04
.48
.03
.18
.38
.21
.03
.17
.05
.18
.18
.31
.21
.13
.08
.16
.43
.23
.16
.17
.18
.35
.28
.27
.43
.27
.15
.05
.25
.36
.40
.50
.08
.13
.50
.24
.15
.06
.02
.13
.29
.22
.33
.49
.37
.26
.26
.02
.03
.11
.11
.04
.22
.13
.11
.35
.43
.19
.28
.41
.22
.35
.03

.21

5.4

11.9

30.9

1.8

26.8

28.7

14.0

24.9

25.9

10.1

1.6

3.9

7.3

11.2

16.2

23.8

11.7

11.7

54.9

24.0

14.0

7.1

2.0

6.1

36.6

24.4

11.8

2.2

43.4

19.0

34.6

27.4

19.3

4.9

5.7

4.9

27.6

25.2

13.1

0

19.3

20.7

30.8

38.6

19.3

11.1

11.7

3.2

17.8

24.9

19.3

34.6

13.9

23.2

28.8

19.9

28.4

19.3

9.6

23.9

9.2

5.5

6.9

4.5

18.8

29.2

3.8

44

27.0

5.7

31.5

11.7

0

20.6

27.6

7.1

14.5

6.2
11.0

5.2
27.9
14.0
24.9
13.0
29.2

1.9
10.1

1.6
10.0
22.6
23.8
11.7
11.7
12.5
24.0
32.2
15.6

2.0
18.0
15.8
41.9
11.8
25.5
23.9
19.0
34.6
30.1
27.8
27.1

5.7

2.3

2.3
23.1
13.1

0
19.3

8.6
31.9
14.8
30.8
27.9
21.1

4.9
37.1
19.9
21.8
34.6

6.6
19.3
28.8

7.2
13.9
19.3

9.6
23.9
11.8

5.5

5.8

4.5

8.0
23.8
22.1

5.7

5.6
21.6
12.8

5.5

0

15.7
41.7

7.1
14.5
32.5

17.17 16.73

16.95

4.2

5.7

19.9

3.4

1.1

14.7

10.9

11.9

3.3

8.2

8.5

2.3

2.7

11.4

7.6

12.1

0

.8

30.9

8.2

1.6

5.1

16.0

9.7

5.3

12.6

13.7

21.7

24.4

15.6

4.5

.4

7.8

.8

3.4

2.6

4.5

12.1

13.1

19.3

10.7

11.2

16.0

7.8

8.6

10.0

6.8

33.9

2.1

3.1

15.3

28.0

5.4

5.6

21.6

6.0

9.1

9.7

14.3

12.1

3.7

.3

2.4

3.5

5.0

7.1

1.9

1.2

5.4

7.1

26.0

11.7

15.7

21.1

20.5

7.4

18.0

9.84

} 4
lll.f

9.65
3.30

6.62

• 5.12

11.92

Ll3. 32

7.44

11. 94

10.07

13.44

• 6.89

4.62

26.00

15.73

Ratio of yield to
rainfall

(0.50

\ .96

12.10

\.18

1.44

2.01

.99

1.76

1.77

' .87

.14

.33

.49

.71

1.02

1.51

.76

.77

2.60

1.16

.97

.52

.15

.46

1.53

1.53

.75

.15

2.26

.99

1.82

1.66

1.52

.46

.54

.46

fl.49

1.53

.81

.00

1.37

.84

1.66

2.04

1.13

.69

1.04

.14

.95

L46

1.07

1.93

.77

1.51

1.88

U-09

rl. 25

.86

.44

1.11

.54

.33

.46

.30

.76

1.35

.23

.25

1.57

.35

1.41

.43

.00

.90

1.28

.33

10

0.89

.52

.75

.52

1.53

.99

1.76

.92

2.02

.17

.87

.14

.68

1.46

1.51

.76

.77

.83

1.16

1.57

1.08

.15

1.33

1.20

1.76

.75

1.65

1.63

.99

1.82

1.62

1.70

2.16

.54

.22

.22

1.27

.81

0

1.37
.62
1.30
.81
1.66
1.67
1.35
.44
1.67
1.09
1.30
1.93
.37
1.07
1.88
.48
.77
.86
.44
1.11
.55
.33
.34
.30
.54
.97
1.02
.35
.32
1.27
.80
.25
0
.59
1.86
.33
.69
1.55

. 988 . 974

0.981

0.39
.44

1.35
.34
.09

1.02
.77
.84
.25
.70
.73
.19
.19
.75
.49
.75
.01
.06

1.44
.41
.11
.37

1.18
.74
.23
.78
.90

1.48

1.27
.83
.20
.04
.64
.08
.32
.24
.22
.72
.81

1.37
.75
.46
.85
.38
.54
.66
.60

1.53
.14
.16
.86

1.56
.30
.37

1.40
.32
.39
.42
.67
.56
.21
.01
.16
.24
.21
.33
.12
.07
.30
.45

1.16
.43
.59
.96
.95
.36

. 572

Table 18. — Deviations of composite yields of small-grain crops as
related to precipitation at 16 field stations in the northern Great
Plains area, arranged in the order of annual precipitation for
use as a key to Figure 67

Field stations

Wiliiston.

Dickinson

do

do

Assinniboine..

Edgeley

Archer

do

do

Assinniboine.

Dickinson

Bellefourche...

do

do

Ardmore

Huntley

do

do

Ardmore

Bellefourche

Sheridan

Wiliiston

Archer.

Mandan

Akron

do

Scottsbluff

Moccasin. .

Scottsbluff

Moccasin

Mandan

Scottsbluff

do....

Archer...

Mandan

Edgeley

Ardmore

North Platte.. _

Ardmore

North Platte...

Dickinson

Akron

Moccasin

Edgeley

Akron

North Platte...

....do

Moccasin

....do....

....do

....do

Ardmore

Huntley

Edgeley

Moccasin

Edgeley

Dickinson

do

do

Bellefourche

Hays

Bellefourche

Hays

....do

North Platte...

Akron

....do

Moccasin

Colby

Akron

Hays.

Akron

Mandan _.

North Platte...

Edgeley

Hays

....do

Average

Mean average

Annual precipitation
(inches)

Pair of

years

1910,
1918,
1911
1911
1922,
1918,
1921
1919
1916.
1924,
1920,
1921
1912,
1917,
1921,
1913,
1923,
1914,
1914
1913,
1920,
1909,
1914
1921
1913
1921
1913,
1913,
1917,
1922,
1923,
1915,
1912,
1924,
1922,
1908,
1919,
1914,
1923,
1917,
1924,
1923,
1911.
1922,
1910,
1924,
1913
1915,
1918,
1910,
1923
1920,
1922,
1906,
1916,
1915,
1909,
1910,
1915,
1924,
1912,
1915,
1913,
1922,
1908,
1912
1919,
1912,
192U,
1920,
1908,
1915,
1915,
1919,
1914,
1909,
1907,

1911
1919
1918
1919
1920
1910
1922
1921
1919
1918
1913
1916
1908
1912
1924
1918
1913
1923
1921
1918
1918
1920
1923
1924
1916
1913
1914
1908
1913
1913
1916
1917
1915
1915
1923
1913
1922
1921
1919
1914
1908
1922
1914
1909
1923
1916
1918
1917
1915
1918
1910
1916
1924
1921
1923
1906
1916
1909
1910
1922
1910
1924
1912
1913
1920
1909
1912
1909
1923
1919
1924
1920
1914
1923
1912
1919
1909

10.02

10.53

10.70

10.70

10.80

11.24

11.59

11.77

11.

12.38

12.71

13.31

13.57

13.74

14.09

14.15

14.17

14.30

14.36

14.45

14.60

14.72

14.80

14.83

14.94

14.97

15.27

15.28

15.30

15.41

15.68

15.78

15.82

15.85

15.99

16.13

16.22

16.27

16.49

16.49

16.55

16.86

17.02

17.12

17.12

17.18

17.88

17.94

18.09

18.11

18.33

18.52

18.66

18.58

18.83

18.94

18.9'

19.13

19.21

20.76

20.95

21.14

21.30

21.52

21.62

21.62

21.99

22.31

22.39

22.48

22.79

22.81

23.97

24.59

24.67

26.81

27.00

10.01
10.35
10.53
10.35
10.78
11.16
11.25
11.59
11.77
11.98
12.55
13.13
13.52
13.57
13.94
14.06
14.15
14.17
14.

14.42
14.48
14.58
14.

14.70
,14.83
14.94
15.09
14.

15.27
15.28
15.47
15.30
15.78
15.50
15.68
15.63
15.79
15.92
16.22
16.27
16.32
16.84
16.78
16.72
16.86
17.0
17.75
17.88
17.94
18.09
18.11
18.24
18.20
18.33
18.33
18.58
18.54
18.97
19.13
20.55
20.92
20.76
20.95
21.30
21.58
21.36
21.62
22.18
21.
21.99
22.38
22.48
23.79
24.48
24.62
26.53
26.81

17.08 16.87
16.97

0.01
.18
.17
.35
.02
.08
.34
.18
.13
.40
.16
.18
.05
.17
.15
. OH
.02
.13
.27
.03
.12
.14
. 12
.13
.11
.03
.18
.29
.03
.13
.21
.48
.04
.35
.31
. 50
.43
. 35
.27
.22
.23
.02
.24
.40
.26
. 11
.13
.06
.IT)
.02
.22
.28
.36
.25
.50
.36
.43
.16
,0s
.21
.03
.38
.35
.22
.04
.26
.37
.13
.43
.49
.41
.33
.18
.11
.05
.28
.19

..'1

Corresponding
crop yields
(bushels)

1.8

5.7

4.9

4.9

5.4

11.7

10.1

1.6

3.9

11.9

19.3

6.1

2.0

7.1

19.3

24.9

14.0

28.7

0

14.0

25.9

30.9

7.3

2.2

4.5

6.9

11.7

28.8

11.7

23.2

11.8

23.8

16.2

11.2

24.4

11.1

13.1

5.7

25.2

3.8

27.4

5.5

24.9

19.3

9.2

27.0

4.4

34.6

19.3

13.9

19.9

27.6

26.8

30.

17.8

38.6

34.6

19.0

43.4

24.0

14.5

54.9

7.1

27.6

29.2

23.9

9.6

3.2

31.5

19.3

20.6

28.4

36.6

18.8

20.7

0

11.7

5.2
2.3
5.7
2.3
9.6
4.9
1.9
10.1
1.6
6.2
27.1
15.8
18.0
2.0
8.6
13.0
24.9
14.0
19.3
15.6
29.2
11.0
10.0
23.9
8.0
4.5
12.5
7.2
11.7
28.8
25.5
11.7
23.8
22.6
11.8
21.1
0

12.8
13.1
5.7
27.8
5.8
21.8
27.9
5.5
21.6
5.6
6.6
34.6
19.3
13.9
23.1
27.9
14.8
19.9
30.
30.1
34.6
19.0
32.2
32.5
24.0
14.5
7.
22.
11.8
23.9
37.1
5.5
9.6
41.7
19.3
41.9
23.8
31.9
15.7
0

17.17 16.73
16.95

3.4
3.4
.8
2.6
4.2
6.8
8.2
8.5
2.3
5.7
7.8
9.7
16.0
5.1
10.7
11.9
10.9
14.7
19.3
1.6
3.3
19.9
2.

21.7
3.5
2.4
.8
21.6
0

5.6
13.7
12.1
7.6
11.4
12.6
10.0
13.1
7.1
12.1
1
.4
.3
3.1
8.6
3.

5.4
1.2
28.0
15.3
5.4
6.0
4.5
1
16.0
2.

7.8
4.5
15.6
24.4
.8.2
18.0
30.9
7.4
20.5
7.1
12.1
14.3
33.9
26.0
9.7
21.1
9.1
5.3
5.0
11.2
15.
11.7

9.84

Ratio of yield
to rainfall

Q

0.18
.54
.46
.46
.50
1.04
.87
.14
.33
.96
1.52
.46
.15
.52
1.37
1.76
.99
2.01
0
.97
1.77
2.10
.49
.15
.30
.46
.77
1.

.76
1.51
.75
1.51
1.02
.71
1.53
.69
.81
.35
1.53
.23
1.66
.33
1.46
1.13
.54
1.57
.25
1.93
1.07
.77
1.09
1.49
1.44
1.

.95
2.04
1.82
.99
2.26
1.16
.69
2.60
.33
1.28
1.35
1.11
.44
.14
1.41
.86
.90
1.25
1.53
.76
.84
.00
.43

10

0.52
.22
.54
.22
.89
.44
.17
.87
.14
.52

2.16

1.20

1.33
.15
.62
.92

L76
.99

1.37

1.

2.02
.75
.68

1.63
.54
.30
.83
.48
.77

1.

1.65
.76

1.51

1.
.75

1.35

0

!si

.35
1.70

.34
1.30
1.67

.33
1.27

.32

.37
1.
1.07

.77
1.27
1.53

.81
1.09
1.

1.62
1.82

.99
1.57
1.55
1.16

.69

.33
1.02

.55
1.11
1.67

.25

.44
1.88

.86
1.76

.9
1.30

.59
0

.974
0.981

11

0.34
.32
.08
.24
.39
.60
.70
.73
.19
.44
.64
.74

1.18
.37
.75
.84
.77

1.02

1.37
.11
.25

1.35
.19

1.48
.24
.16
.06

1.40
.01
.37
.90
.75
.49
.75
.78
.66
.81
.45
.72
.12
.04
.01
.16
.54
.21
.30
.07

1.56
.86
.30
.32
.22
.09
.85
.14
.38
.20
.83

1.27
.41
.86

1.44
.36
.95
.33
.56
.67

1.53

1.16
.42
.96
.39
.23
.21
.46
.59
.43

.572

Table 18 contains the same data as Table 17, but so
arranged as to serve as a key to Figure 67. In Table 18
there is no grouping by stations, as has been done in the
other tables; but each pair of years is arranged in the
order of magnitude of the annual precipitation, to cor-
respond with the graphical arrangement of these data in

92

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

BUSHELS

1.5

DEVIATIONS IN RATIOS- BUSHELS PER INCH OF ANNUAL PRECIPITATION

1.0

Jill]

6 e to 12

16 IS 20 22 24 26 28 30 32 34 36 38 40 42 44 4* 48 SO 52 54 56 S8 60 62 64 66 68 TO 72 74 76

50

45

40

35

30

25

20

15

10

DEVIATIONS IN YIELDS PER ACRE

Maximum 33.90 Bu.
Mean 9.8* "

Minimum .30 "

DEVIATIONS IN ANNUAL PRECIPITATION

Maxim um .5 0 inches
Mean .21 "

Minimum .02 "

II 13 IS 17 19 21 23 25 27 29 31 33 3S 37 39 41 43

49 51 S3 55 57 S9 61 63 65 67 69 71 73 75 77

Fio. (.7— Diagram showing the deviations in OOmposlte OOP yield and ratios In 77 instances where the difference in annual prci-ipit :it ion.

in two diiTereui >•< .r ,w . ii than one-half inch at the Mine station, with the same crops, the nine soO, the same tillage methods, and
the same crop scqueure, bI 16 field station In tbo northern Great Plains. (See Tables 17 and 18)

CROP YIELDS AND PRECIPITATION IN THE GREAT PLAINS AREA

93

Figure 67. In Table 18 the numbers from 1 to 77, in-
clusive, which are used to indicate the pairs of years, are
found in the first column, while in Figure 67 the even-
numbered designations are found extending from left
to right across near the top of the page, and the odd
numbers in like manner appear near the bottom.

There are a number of facts concerning Table 17
that make it of more value than is perhaps apparent.
Although it presents the results of only 129 crop years,
it embodies facts that are as representative of condi-
tions as those contained in other tables dealing with the
results of 218 or 303 years. It contains the data for
all the crop years at the 16 northern field stations
where there were one or more pairs of years having
annual precipitations differing by less than one-half
inch. The range in annual precipitation is from 10.01
to 27 inches. The yields are from 0 to 54.9 bushels per
acre. The average annual precipitation for all crop
years used is 16.97 inches, whereas the average for 218
crop years is 16.54, a difference of only 0.43 inch.
The average yields are 16.95 bushels per acre as com-
pared with 16.10 bushels, a difference of 0.85 bushel.
Although the average deviation in annual precipitation
is only 0.21 inch, the average deviation in crop yields
regardless of station grouping is 9.84 bushels per acre,
ranging from 0 to 33.9 bushels.

There is, of course, a rather wide range of average
deviations for the several stations as compared with
one another, but there is also a wide range in the
number of crop years available for comparison. The
lowest deviation for any station is 3.3 bushels at
Sheridan, and the highest 26 bushels at Colby. Data
are available for but one comparison at either of these
stations. The largest number of comparisons is 9, at
Moccasin, and the average deviation for this station
is 13.44 bushels per acre. The mean of the average
deviations of the 16 stations is 10.17 bushels.

The figures in column 12, at the extreme right of
the table, headed "Key," refer to the numerical des-
ignations of the several crop years in Figure 67 and
in Table 18.

Figure 67 is self-explanatory, but attention is called
to the following significant features:

It will be noted that the ratios of bushels of grain to
inches of annual precipitation shown by the approxi-
mately parallel lines running across the lower portion
of the diagram show no continuing trend beyond the
first ten. In other words, the average number of
bushels of grain produced per inch of annual precipita-
tion was practically the same whether the annual
precipitation was 12 or 27 inches.

The main portion of the diagram is devoted to com-
parisons of yields and annual precipitation, and shows
some remarkable differences in yields without any
corresponding differences in annual precipitation; the
maximum deviation in crop yields being 33.90 bushels,
the mean 9.84 bushels, and the minimum 0.30; whereas
the maximum deviation in annual precipitation was
0.50 inch per annum, the mean 0.21, and the minimum
0.02 inch.

The deviation in ratios between the same plats with
the same crops, the same sequence and tillage methods,
and with within one-half inch of the same annual
precipitation, in different years, as shown in the upper
portion of the diagram, shows the same general degree
of departure throughout the entire range from 10 to
27 inches of annual precipitation.

The data representing crop yields in the main diagram
are based upon the averages of 75 plats for each station

year, and as two station years are represented by each
of the 77 heavy vertical lines the total number of yields
represented in the diagram is 75 by 77 by 2 = 11,550,
which affords 77 comparisons of the average yields of
groups of 75 plat yields. The distribution of yields as
compared with annual precipitation in the figure is so
erratic, considering the large number of plats involved,
that it seemed desirable to concentrate the figures still
further.

The 77 comparisons, therefore, were regrouped into
7 classes. The averages for these 7 classes, each repre-
senting 1,650 individual plat yields, are shown in the
inset. Class 1, representing those plat years, has an
average annual precipitation of 11.30 inches and an
average yield of 7.18 bushels per acre; class 2, 14.13
inches annual precipitation and yields of 15.65 bushels;
class 3, 15.28 inches and 14.35 bushels; class 4, 16.45
inches and 15.54 bushels; class 5, 18.10 inches and 19.28
bushels; class 6, 20.47 inches and 26.16 bushels; class
7, 23.80 inches and 20.49 bushels. The ratios of
bushels of grain per inch of annual precipitation for
these 7 classes, respectively, were as follows: 0.64, 1.11,
0.94, 0.94, 1.07, 1.28, and 0.86. The mean ratio for
the entire series as shown in Table 17 is 0.98. If, now,
we multiply the inches of annual precipitation for each
of these 7 classes by 0.98 we get the following figures as
the respective yields that would have been produced
if the inhibiting factors had been normal for all 7
classes: 11.07, 13.85, 14.97, 16.12, 17.74, 20.06, 23.32.
The differences between these calculated yields and
those which were actually obtained give the following
values for the inhibiting factors : —3.89, +1.80, —0.62,
-0.58, +1.54, +6.10, and -2.83 bushels per acre
thus showing the relative potency of inhibiting factors.

The lines in the inset marked "high yields" and
"low yields" show in a striking way the range of the
yields from which the mean yields are computed.
This range far exceeds that of the difference in mean
yields of the classes having the highest and the lowest
annual precipitation. Further comment seems unneces-
sary.

SUMMARY AND RECOMMENDATIONS

This publication will make available to other inves-
tigators, and to the general public, some basic data
heretofore unavailable. It is believed by the writer
that these data may be more valuable than are the
interpretations of them herein presented. It is hoped
that they may be fully utilized.

At the present stage of these investigations the
results seem to indicate certain outstanding features.

Notwithstanding the fact that annual precipitation
is a vital factor in determining crop yield, it is seldom
if ever the dominant factor; but the limitation of crop
yield is most frequently due to the operation of one or
of several inhibiting factors other than shortage of
rainfall.

Yields equivalent to 10 bushels or less per acre of
wheat have occurred in 75 of the 218 crop years during
which these investigations have been conducted at 16
stations on the northern Great Plains. During 23 of
these 75 years the annual precipitation was less than
12 inches. During the remaining 52 of the 75 crop
years the low yields were due to inhibiting factors
other than inadequate annual precipitation. But,
nevertheless, the composite crop yields have averaged
throughout the entire 218 crop years the equivalent
of 16.1 bushels of wheat per acre.

94

MISCELLANEOUS CIRCULAR 81, U. S. DEPARTMENT OF AGRICULTURE

The mean annual precipitation of the Great Plains
as represented by the 23 dry-land field stations is
sufficient to produce crops equivalent to those obtained
at the 16 stations if the inhibiting factors are no more
potent than they have been during the period covered
by these investigations.

With respect to climatic conditions, no extensive
portion of the Great Plains as represented by these
field stations is markedly superior or inferior to any
other portion; but the accumulated experience of
practical farmers may, in the future, afford a basis for
revising present-day estimates of relative agricultural
possibilities.

It is highly desirable that the fullest possible knowl-
edge be acquired concerning the climatic conditions of
the Great Plains. Such information is indispensable
to the farmers of this region when planning their crop-
ping systems. Many of the inhibiting factors which
limit crop yields are meteorological in character; and
others, such as insects and diseases, are very susceptible
to climatic conditions.

Although the United States Department of Agri-
culture and the State experiment stations can render
important assistance and should continue to do so,
the ultimate solution of the problems of crop produc-
tion can be attained only by practical farmers.

The agricultural development should be slow, there
being neither economic justification nor adequate
knowledge to bring the Great Plains up to its full
agricultural possibilities in the near future.

It will be impracticable to effect any detailed agri-
cultural classification of the land in the semiarid portions

of the Great Plains, based upon either meteorological
data, native vegetation, or soil types, until a much
more stable background of agricultural experience
has been established.

The Great Plains area has been and should continue
to be chiefly devoted to stock raising, and all agencies
interested in the agricultural, social, and economic
development of this vast region of more than 450.000
square miles should unite in bringing about conditions
that will make possible the fullest development of its
natural resources for stock production. Crop produc-
tion should be aimed to supplement livestock produc-
tion rather than to compete with it.

When sufficient experience has been acquired as to
the crops and the farming practices best adapted to
local conditions, the enterprise of pioneer farmers can
be depended upon to develop the agriculture of the
Great Plains as rapidly as is justified by economic
conditions. No artificial stimulation of land settle-
ment in this region is justified at the present time.

In its present state of agricultural development, land
prices and local taxes in general are too high in pro-
portion to the revenue-producing capacity of the
region.

For the homeseeker with small capital and without
practical agricultural experience on the Great Plains
the chances of success are remote. But where prac-
tical experience and adequate capital combine, and
when a real economic demand for increased agricul-
tural production develops, the Great Plains of America
are destined to become one of the world's greatest
food-producing .regions.

o

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