16 
BULLETIN 1293, U. S. DEPARTMENT OP AGRICULTURE 
Table 8. — Average yields of wheat, oats, and barley on disked corn ground, 
fallow, and green-manured land at Dickinson. Hettinger, and Williston, 
N. Dak., for the periods specified 
[Yields in bushels per acre] 
Dickinson, 1908 to 1923 
Hettinger, 1912 to 1922 Williston, 1910 to 1920 
Crop 
Disked 
corn 
'*i 
Disked 
corn 
Fallow 
Green Disked 
manure corn 
Fallow 
Green 
manure 
Wheat . '.... 
19.7 
39.8 
27.6 
21.5 
45.5 
26.6 
17.4 
42.0 
15.4 
32.2 
16.9 
35.4 
28.6 
13.2 14.4 
26.9 33.4 
23.8 
18.0 
40.0 
16.7 
Oats - .- 
32 ft 
Barley - ..... 
28.7 
There seems to be no evidence of a cumulative effect of green 
manure. The relative yields of corn the second year after fallow 
and after green manure did not change during the periods of the 
experiments. During the four-year period from 1917 to 1920, when 
corn yields were low, the yield of corn fodder was lower after green 
manure than after fallow. In similar experiments at Edgeley, N. 
Dak., 3 a tendency toward increased yields of corn in the rotations 
containing sweet clover as a green manure was noted during the 
later years of their history. 
Since green-manure crops require an added expense for seed and 
seeding and the benefits to subsequent crops are negligible, there is 
no economic basis for their use. Possibly a longer history may 
bring out benefits which have not yet become apparent. 
RESULTS WITH SOD CROPS 
In more humid regions sod crops generally benefit succeeding 
crops, particularly if the sod crop be a legume. Results of these 
experiments indicate that in this district the yields of grain fol- 
lowing sod are lower than following either corn or fallow and that 
there is no significant difference in the yields following alfalfa and 
bromegrass. 
Three sod crops were included in the rotations at Dickinson and 
at Hettinger and two at Williston. At Dickinson bromegrass is 
included in rotations Nos. 10 and 12, alfalfa in No. 42, and sweet 
clover in No. 11. At Hettinger bromegrass was in rotations Nos. 
12 and 41, alfalfa in No. 42, and sweet clover in No. 11. At Willis- 
ton bromegrass was in rotations Nos. 10 and 12. The details of the 
sod rotations are as follows: 
No. 10, Bromegrass, bromegrass, oats, corn, and wheat. 
No. 12, Bromegrass, bromegrass, flax, oats, corn, and wheat. 
No. 41, Bromegrass, bromegrass, bromegrass, oats. corn, and wheat. 
No. 11, Sweet clover, sw T eet clover, oats, corn, and wheat. 
No. 42, Alfalfa, alfalfa, alfalfa, oats, corn, and wheat. 
The bromegrass was sown in the spring with the wheat. This 
method of seeding has the advantage of avoiding the loss of the 
use of the land for a season. A full stand usually did not develop 
until the plants spread in the second year. In several dry years 
the stand was lost and reseeding was necessary. At Williston 
slender wheatgrass was substituted for the bromegrass in rotations 
3 Colo. J. S. Crop rotation arid cultural methods at Edgeley, X. Dak. T". S. Dept. Agr. 
Bui. 991. 24 ].., illus. 1021. 
