TILLAGE AND ROTATION EXPERIMENTS, NORTH DAKOTA 3 
Table 1. — Average annual and warm-season precipitation at Dickinson, llet- 
Under, Williston, and Bismarck, X. Dak., and MoorheaS, Minn., from the 
establishment of the Weather Bureau stations to 1920, inclusive^ 
Station 
Dickinson 
Hettinger. 
Williston. 
Bismarck. 
Moorhead 
Alti- 
tude 
(feet) 
2,543 
2,675 
1,875 
1,674 
935 
Length 
of 
record 
(years) 
Precipitation 
Annual 
(inches) 
15.41 
14.52 
14.42 
17.10 
23.62 
April to July j April to August Ap [ em l De b r ' 
April to Sep- 
Inches 
9.02 
9.31 
8.11 
9.68 
12.67 
Per- 
cent- 
age of 
annual 
58.5 
64.1 
56.2 
56.6 
53.6 
Inches 
10.97 
10.56 
9.78 
11.67 
15.66 
Per- 
annual 
71.2 
72.7 
67.8 
68.2 
12.04 
11.86 
10.79 
12.92 
17.85 
Per- 
cent- 
age of 
annual 
78.1 
81.7 
74.8 
75.6 
75.6 
1 U. S. Department of Agriculture, Weather Bureau. Summary of the climatological data for the 
United States . . . from the establishment of the stations to 1920, inclusive. Reprint of Section 31— 
Western North Dakota. 15 p. 1922. 
Summary of the climatological data for the United States . . . from the establishment 
of the stations to 1920, inclusive. Reprint of Section 57 — Northern Minnesota. 15 p. 1923. 
Although the average distribution of rainfall is favorable, any 
single year or period may so deviate from the average as greatly 
to affect crop yields. The annual precipitation at the Dickinson 
station during the period of the experiments ranged from more than 
±1 inches in 1914 to less than 9 inches in 1919. The June rainfall, 
which affects the yields of crops in general more than that of any 
other month, varied during the same period from more than 7 inches 
m 1914 to only slightly more than 0.5 inch in 1919. 
EVAPORATION 
The three stations vary but little in the quantity of water lost 
by evaporation from an open tank. The average evaporation for 
each month from April to September, inclusive, is given in Table 
2. The amount increases from April to July, then decreases during 
August and September. The average evaporation for the six months 
was 32.689 inches at Dickinson. 33.368 inches at Hettinger, and 
33.104 inches at Williston. The greatest range between years was at 
Hettinger, where a minimum of 25.495 inches was recorded in 1915 
and a maximum of 44.653 inches in 1911. 
Table 2. — Average monthly and seasonal evaporation at Dickinson, Hettinger, 
and Williston, N. Dak., from April to September, inclusive, for the periods 
specified 
Period of 
record 
1907 to 1923... . 
1911 to 1921.... 
1909 to 1918 
Evaporation (inches) 
Station 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Season 
al 
3.683 
3.997 
4. 146 
5.007 
5.061 
5.599 
6.189 
6.451 
6.376 
7.052 
7.331 
7.145 
6. 427 
6.360 
6.070 
4.331 
4.168 
3.768 
32. 689 
Hettinger 
33. 368 
Williston 
33. 104 
1 From records of the Office of Biophysical Investigations, Bureau of Plant Industry, U. S. Department 
of Agriculture. 
