20 
BULLETIN/ 991, r. S. DEPARTMENT OE AGRICULTURE. 
reasonably be expected to overcome the effect of the seasonal condi- 
tions as fully as any cultural method. There should at least be offered 
as wide a contrast between fallow and cropped land in their control 
by seasonal conditions as between any methods that might be selected, 
In rotation Xo. 5 wheat is on fallow, and in rotation Xo. S. it fol- 
lows oats. In rotation No. 8 the oat crop is on fallow and in Xo. 5 it 
follows wheat. The yields of these two crops in these rotations are 
given in Table II for each year of the 14-year period from 1906 to 
1919. In 1906. the first year, neither plat was on fallow, but all 
were on land in variety tests of small grain in 1905. The yields 
from 1907 to 1919 are shown graphically in figure 1. The upper 
portion of this diagram gives the yields of oats and the lower por- 
tion the yields of wheat. The yields on fallow are shown by circles 
connected by a solid line and the yields on land producing a crop 
the year before by crosses connected with a broken line. Both the 
figures of yield and the diagram are so clear as to need little com- 
ment. The yields of both methods go up or down with the seasons 
to a degree altogether disproportionate to any differences between 
the methods themselves. 
Table II. — Annual yields of wheat on falloic in rotation Xo. 5 and following 
oats in rotation Xo. 8, and of oats on falloic in rotation Xo. 8 and following 
wheat in rotation Xo. o. showing the controlling effect of seasonal conditions 
at Edueley. X. Dak., during the 14-year period from 1906 to 1919, inclusive. 
Yields per acre. 
Year. 
Yields per acre. 
Year. 
Wheat. Oats. 
Wheat. Oats. 
Rota- 
tion 
Xo. 5. 
Rota- Rota- 
tion tion 
Xo. 8. Xo. S. 
Rota- 
tion 
Xo. 5. 
Rota- 
tion 
Xo. 5. 
Rota- 
tion 
No. 8. 
Rota- Rota- 
tion tion 
No. S. No. 5. 
1906 
Bushels. 
15. S 
30.3 
11.8 
19.5 
29.8 
7.8 
2.7 
39.0 
25.3 
Bushels. Bushels. 
15. 50. 
27.5 63. S 
n 5 30. 9 
10.3 20.9 
26.6 56.2 
8.3 1 10.0 
.7 6.1 
28. 2 72. 5 
17. 1 46. 2 
Bushels. 
55.6 
57.5 
27.5 
33.4 
63.7 
13.7 
4.4 
65.9 
36.2 
1915. 
1916. 
1917. 
1918. 
1919. 
Bushels. 
3& 7 
9.2 
10.0 
20.5 
1.7 
Bushels. 
37.0 
10.5 
13.3 
7.0 
2.8 
Bushels. 
100.7 
Bushels- 
82.2 
1907 
190S 
Average, 
1907-1919. 
26.9 
8.1 
27.8 
11.8 
19.1 
16.9 
1909 
1910 
1911 
1912 
1913 
1914 
15.6 
22.8 
17. S 
14.1 
36.0 
35.2 
Several causes conspire to make this so, or there are several 
reasons why it is so. The season may be so dry. as in 1910 and 
1911. that both methods are more or less complete failures, or the 
season may be so wet that both methods produce heavily, as in 1912 
and 1915. The fallow season may be so dry that it is impossible to 
store water in the fallow, in which case it possesses no advantage 
in this respect over a cropped plat, or the rainfall between harvest 
and seeding may be so abundant that the cropped as well as the 
fallow plat is filled with water, in which case again the fallow would 
have no advantage so far as water supply is concerned. This is an 
especially common occurrence in a shallow soil of limited water- 
storage capacity and with a rainfall as high as that at Edgeley. 
Another factor that equalizes yields by reducing all to a common 
