20 BULLETIN 1293, U. S. DEPARTMENT OF AGRICULTURE 
With barley at Dickinson the relative decrease with continuous 
cropping was not quite so great as with oats and wheat. Plats A 
and B averaged 21.4 and 20.5 bushels, while on the fallow plats C 
and D the average was 26.6 bushels. The average of the five plats 
of barley grown in the rotations was 23.7 bushels. The A plat- 
yielded 5.2 bushels less than the plat on alternate fallow and 2.3 
bushels less than the average of five plats. The low average of bar- 
ley in relation to the average yield of" oats and wheat is owing to 
the fact that since only five plats are grown the two continuously 
cropped plats reduce the average. 
At Hettinger the reduction in yields of the small grains by con- 
tinuous cropping was very similar to that at Dickinson. Wheat on 
plats A and B averaged 11.5 and 8.9 bushels, respectively, and on 
fallow on plats C and D 16.9 bushels. Oats on plats A and B 
averaged 31 and 31.1 bushels, respectively, and on fallow 42.9 bush- 
els. Barley on the spring-plowed and fall-plowed plats A and B 
averaged 21.4 and 20. T bushels and on C and D 28.6 bushels. 
Continuously cropped small grains at Williston show a greater 
contrast with the yields after fallow than is shown at either of the 
other stations. On the A and B plats in the wheat series the yields 
were 12.1 and 11.5 bushels, respectively, for the spring-plowed and 
fall-plowed plats and 18.6 bushels on fallow. Oats on the A plat 
averaged 23.2 bushels, on the B plat 24 bushels, and on the C and D 
plats on fallow 40.6 bushels. Barley on the A plat averaged 13 
bushels, on the B plat 13.1 bushels, and on the C and D plats 28.7 
bushels. 
Continuous cropping to corn has resulted in increased yields in 
contrast to the decrease noted for all small grains. The increased 
yield of grain on the continuously cropped corn plats has been con- 
sistent throughout the period of the experiments. Like the small 
grains, there was little difference between the average results on 
spring plowing and fall plowing, and there was also a response to 
fallow. At Dickinson continuous corn on spring plowing averaged 
16.9 bushels, on fall plowing 16.5 bushels, and on fallow 17.4 bush- 
els. At Williston continuous corn on spring plowing averaged 15.8 
bushels, on fall plowing 15.6 bushels, and on fallow 18.9 bushels. 
Although the yields of ear corn have been greater on continuous 
cropping, there was a reduction in the quantity of fodder pro- 
duced at Dickinson. The yield of fodder was 3,343 pounds on spring 
plowing, 3,305 pounds on fall plowing, and 3,248 pounds on fallow, 
all below the average of all plats in the rotations. At Williston the 
three continuously cropped plats were above the average of all plats. 
The average on spring plowing was 4,947 pounds, on fall plow- 
ing 5,093 pounds, and on fallow 6,209 pounds. At Hettinger the 
yields of green corn for silage were 6,396 pounds on spring plowing, 
7,021 pounds on fall plowing, and 5,627 pounds on fallow, the latter 
weight being below the average of all plats. 
A definite decrease in the production of small grains occurs when 
these crops are grown continuously. This decrease is greater in 
some years than others, owing to the response to tillage and to sea- 
sonal Variation, but has been consistent through the later years of 
the experiments. From all evidence the decrease is due to weeds 
in these plats rather than to lack of fertility or other causes. At 
