CEOP PRODUCTION IN THE GREAT PLAINS AREA. 6 
tions of the Bureau of Plant Industry. The entire scientific staff of 
the Office of Dry-Land Agriculture, numbering about 30 men, has 
participated in the details of the field work and the preparation of 
the data for publication. The investigations have also had the benefit 
of the counsel and advice of the scientists connected with the various 
cooperating offices and State agricultural experiment stations. 
CLIMATIC FEATURES OF THE GREAT PLAINS. 
The climate of the Great Plains has been classified as semiarid. It 
may be better to say that it is variable. One season may have almost 
humid and another almost arid conditions. The mean annual pre- 
cipitation is relatively low. Years of relatively high precipitation 
may be followed by years of relatively low precipitation. Other 
climatic factors usually correspond with the rainfall. In a year of 
relatively high rainfall there will be a lower rate of evaporation and 
higher humidity than in a year of low rainfall. 
Another climatic factor of much importance in crop production 
on the Plains is the distribution of the rainfall. This is probably 
more important in crop production than the amount of annual rain- 
fall. A relatively low rainfall, properly distributed, may produce 
a crop where a much higher rainfall, unfavorably distributed, may 
accompany a crop failure. 
Table I. — Annual and seasonal precipitation and seasonal evaporation at fourteen 
stations in the Great Plains area. 1 
Station. 
I udith Basin. . 
[untley 
T illiston 
)ickinson 
Edgeley 
Hettinger 
Belle Fourche 
Scottsbluft - ... 
North Platte. 
Akron 
Hays 
Garden City.. 
Dalhart 
Amarillo 
Alti- 
tude 
(feet) 2 . 
4,228 
3,000 
1,875 
2, 543 
1,468 
2,253 
2,950 
3,950 
3,000 
4,600 
2,050 
2,900 
4,000 
3,676 
Precipitation (inches) 3 . 
Annual. 
Mini- 
mum. 
14.96 
11.92 
10.28 
11.93 
11.94 
12.72 
6.64 
13.77 
11.18 
14.51 
15.59 
11.82 
13.69 
10.69 
Maxi- 
mum. 
23.78 
11.92 
18.99 
21.22 
21.95 
15.68 
17.73 
18.51 
23.01 
22.46 
27.80 
23. 58 
16. 35 
27.80 
Aver- 
age. 
18.06 
11.92 
14.84 
16.69 
16.71 
14.20 
13.11 
16.14 
18. 05 
18.28 
21.30 
18.54 
15.11 
18.28 
Seasonal. 
Mini- 
mum. 
7.04 
5.92 
4.75 
6.85 
7.85 
8.92 
4.08 
2.53 
6.85 
6.42 
8.18 
2.79 
5.09 
6.17 
Maxi- 
mum. 
17.21 
6.02 
14.49 
16.28 
14.98 
12.47 
9.78 
8.52 
12.66 
13.86 
17.97 
14.43 
9.85 
11.38 
Aver- 
9.34 
5.97 
9.66 
9.79 
10.11 
10.36 
6.90 
4.69 
9.45 
9.02 
11.17 
8.65 
8.01 
P. 13 
Seasonal evaporation. 3 
Mini- 
mum. 
22.012 
23. 754 
20. 422 
20. 673 
18. 663 
21. 539 
26. 472 
23. 804 
28. 445 
26. 064 
30. 625 
34. 325 
35. 459 
33. 804 
Maxi- 
mum. 
29.353 
24. 214 
26. 877 
25. 745 
24. 893 
28. 239 
33. 750 
29. 381 
38. 168 
35. 654 
44. 373 
43. 510 
41. 748 
42. 076 
Aver- 
age. 
24. 491 
23. 984 
24. 216 
23. 919 
21. 866 
24. 639 
28. 794 
26. 081 
32. 359 
31. 420 
35. 790 
38. 185 
38. 988 
36. 724 
1 The years covered are the same as for the data shown in the tables for the several stations. 
2 The altitude given is for the field where the work was done and is based in most cases on that of the 
nearest town. 
3 The records of annual precipitation for 1914 are not included. The records of seasonal precipitation 
and evaporation for 1914 are included for all stations, being figured from May 1 to Sept. 1. Evaporation 
measurements are made from a free water surface, in a tank sunk into the soil to almost its full depth. The 
water surface is kept about level with the surface of the ground. 
