4 buIxLeti:n" 1306, u. s. depaetment of agriculture 
at the Sheridan Field Station during the seven years from 1917 to 
1923, inclusive, are given in Table 3. 
Table 2. — Monthly evaporation, mean temperature, and mean wind velocity at 
the Sheridan Field Station from April to September, inclusive, for the seven years 
from 1917 to 1923, inclusive 
EvAPOKATioN (Inches). 
Year 
AprO 
May 
June 
July 
August 
Septem- 
Seasonal, 
April to 
Septem- 
1917 
3.139 
2.948 
3.563 
2.100 
4.599 
2.659 
2.766 
4.909 
4.181 
6.899 
4.128 
4.715 
4.275 
4.655 
5.819 
6.368 
8.976 
5.255 
7.045 
6.031 
5.327 
9.810 
6.694 
10.297 
6.754 
9.647 
5.980 
7.846 
7.850 
7.503 
8.770 
7.152 
7.922 
6.610 
5.635 
5.138 
3.873 
5.158 
5.083 
5.310 
5.531 
5.352 
36. 665 
1918 
31. 567 
1919 - 
43. 663 
1920 
30. 472 
1921 . 
39. 238 
1922 
31. 086 
1923 
31. 581 
Average.. 
3.111 
4.823 
6.403 
8.147 
7.349 
5.064 
34. 897 
Mean Temperature (° F.). 
1917..... 
1918 
1919. 
1920 
1921. 
1922 
1923 
Average 
63 
58 
Wind Velocity (Miles per Hour). 
1917. 
1918. 
1919. 
1920. 
1921. 
1922. 
1923. 
5.9 
6.8 
5.9 
6.1 
7.4 
6.0 
4.7 
6.4 
5.0 
6.1 
6.0 
6.4 
6.6 
5.2 
6.0 
5.2 
3.9 
6.1 
4.1 
5.2 
2.7 
4.1 
4.3 
3.4 
5.3 
2.8 
4.7 
2.1 
3.7 
3.8 
4.2 
3.8 
3.5 
3.7 
4.3 
2.2 
3.0 
4.4 
3.5 
2.0 
3.3 
6.7 
2.3 
3.8 
3.7 
Table 3. — Dates of the last frost in spring and the first frost in the fall and the 
number of frost-free days at the Sheridan Field Station for the seven years from 
1917 to 1923, inclusive 
Year 
T.ast frost in spring 
First frost in fall 
Frost-free 
period 
(days) 
1917 
June 1 
October 8... 
129 
1918 , - 
May 27 
June 22 
October 18 
October 9 
144 
1919 
109 
1920 
A pril 26 
August 29- 
125 
1921 
May 13 
September 11. 
September 30 
October 12 
September 29 
121 
1922 
May 12 
141 
1923 
Mav 16 
149 
May 21 
Average ... 
131 
ROTATION AND TILLAGE EXPERIMENTS . 
The experiments with crop rotations and tillage methods occuj)y 
240 tenth-acre plats. Of this numlxT, 204 plats were started in 
1917 and 36 in 1920. The crops grown and the number of plats 
I 
