TILLAGE AND ROTATION EXPERIMENTS, NORTH DAKOTA 
19 
31.4 bushels and on fall-plowed grain stubble 28.2 bushels. Corn 
in the sod rotations averaged less than on either spring plowing 
or fall plowing in other rotations. Wheat after bromegrass aver- 
aged 13.8 bushels in rotation No. 10 and 14.7 bushels in rotation 
Xo. 12. or 14.3 bushels for the two. The average yield of wheat 
on seven disked corn plats was 14.4 bushels, so there is no benefit 
apparent from the sod crops. 
When all factors are considered it is not clear that alfalfa in a 
rotation on dry lands benefits the succeeding* crop to any extent. 
In similar experiments under irrigation a substantial benefit fol- 
lows alfalfa. 
RESULTS WITH CONTINUOUS CROPPING 
A series of plats cropped continuously to wheat, oats, barley, and 
corn is included at each of the three stations. In this series each 
crop occupies four plats. Plot A bears the same crop each year on 
shallow spring plowing. Plat B is an adjacent plat continuously 
cropped on fall plowing. Plats C and D alternate with the crop 
and fallow. 
Average yields of the continuously cropped series for the period 
of the experiments at each station are assembled in Table 10. With 
the exception of corn, the yields on the continuously cropped plats 
are distinctly lower than the yields in rotations with other crops or 
after fallow. As an example, wheat at Dickinson on plat A. spring 
plowed, and plat B, fall plowed, averaged 12.7 and 12.5 bushels, 
respectively. All wheat in the rotations averaged 18.4 bushels, an 
increase of 5.7 bushels, or almost 45 per cent more than the con- 
tinuously cropped plat on spring plowing. Wheat on the C and 
D plats on fallow averaged 20.9 bushels, an increase of 8.2 bushels, 
or 65 per cent, more than the spring-plowed plat. 
Almost as great a relative decrease occurred at Dickinson when 
oats were continuously cropped. The A and B plats in the con- 
tinuous series averaged 27.5 and 27.8 bushels, respectively. All oats 
in the rotations averaged 37.7 bushels and on the C and D plats on 
fallow 45.5 bushels. Thus the A plat, spring plowed and cropped 
continuously, yielded 10.2 bushels less than the average of all plats 
and 18 bushels less than on alternate fallow. 
Table 10. — Average yields of wheat, oats, barley, and com continuously 
cropped on spring "plowing, fall plowing, and on fallow at Dickinson. Hettin- 
ger, and WUliston, X. Dak., for the periods specified 
Station, years grown, plat, and method 
Wheat 
Oats 
Barley 
Corn i 
Grain 
Fodder 
Dickinson. 1908 to 1923: 
A, spring plowed 
B, fall plowed ... - 
Bushels 
12.7 
12.5 
20.9 
11.5 
8.9 
16.9 
12.1 
11.5 
18.6 
Bvshels 
27.5 
27.8 
45. 5 
31.0 
31.1 
42.9 
23.2 
24.0 
40.6 
Bushels 
21.4 
20.5 
26.6 
21.4 
20.7 
28.6 
13.0 
13.1 
28.7 
Bushels 
16.9 
16.5 
17.4 
Pounds 
3. 343 
3,305 
C and D. fallow 
Hettinger, 1912 to 1922: 
A, spring plowed 
B, fall plowed 
C and D, fallow 
Williston, 1910 to 1920: 
A, spring plowed 
B. fall plowed 
C and D. fallow 
3.2 is 
6,39(1 
7. 02 1 
5, 627 
15.8 
15.6 
18.9 
4. '.'47 
5, 093 
6, 20'.' 
1 Yields of corn at Hettinger are total wet weights as harvested for silage. 
