8 
BULLETIN 1310, U. S. DEPARTMENT OF AGRICULTURE 
RESULTS WITH FALLOW AND GREEN MANURES 
Rotations including fallow and green manures were started in 
1916. As the green manures are modified fallows, in that the crops 
are turned under before maturity and the ground then treated as 
fallow for the remainder of the season, the results are presented for 
comparison. In the series of rotations offering these comparisons 
the fallow and the green manures each occur in 4-year rotations. 
In one group of these rotations the fallow and green manures are 
followed by winter wheat, and in another group they are followed 
by oats. In both groups the third crop is corn, and the fourth crop 
is oats where winter wheat precedes the corn and winter wheat 
where oats precede it. 
The crops grown for green manure were winter rye, field peas, and 
biennial sweet clover. Winter rye was seeded on fall plowing when 
the conditions were favorable for plowing in the fall and was drilled 
in stubble when the fall was dry. Field peas were seeded on fall 
plowing left rough during the winter, with the seed bed prepared in 
the spring the same as for spring grains. Sweet clover was seeded in 
the spring with oats or with winter wheat which was seeded the pre- 
vious fall. Its first-year growth was with a grain crop, the fourth 
crop in the 4-year rotation, and it was plowed under in its second 
year. 
All crops were plowed under when in bloom. The quantity of 
material turned under varied with the seasons, just as the quantity 
of the harvested crop varied. The stand of field peas was about the 
same each year, but in seasons of light rainfall the growth was light 
and often weedy. While winter rye entirely winterkilled only once, 
the stand of this crop was sometimes affected by winterkilling and 
varied somewhat from year to year. The growth of this crop at 
the time it was plowed under varied from 18 to 42 inches in 
height. Weed growth in winter rye was very light. Sweet clover 
either failed to survive the first summer or winterkilled, so that the 
stands were generally thin and the growth for turning under light. 
Table 5. 
-Annual and average yields of oats and winter wheat on fallow and green 
manures. 1917 to 1928, inclusive 
Rota- 
tion 
No. 
Green-manure crop 
Yields per acre (hushels) 
Crop 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
Aver- 
age 
Oats .- 
f 114 
\ 116 
I 131 
Winter rye 
Field peas .. 
17.8 
16.6 
2.8 
10.9 
4.4 
5.3 
0.6 
3.1 
.9 
18.1 
21.6 
18.1 
18.8 
21.6 
30.3 
12.2 
13.8 
9.7 
10.3 
13.8 
14.7 
12.7 
13.6 
Sweet clover 
11.7 
12.4 
6.9 
1.5 
19. 3 
23. 6 
11.9 
12.9 
12.7 
119 
f 115 
\ 117 
I 132 
Fallow 
Oats. 
25.6 
10.9 
3.1 
28. 4 
35.3 
28. 8 
33.8 
23.7 
Winter rye .. ... 



4.3 
7.7 
5.7 
.8 
2.3 
2.5 
2.5 
5.5 
5.0 
5.2 
7.5 
10.0 
2.3 
8.2 
4.2 



2.2 
Winter wheat ' . 
Field peas 
4.5 
Sweet clover 
3.9 
Average 

5.9 
1.9 
4.3 
7.6 
4.9 

3.5 
118 
Fallow . 
Winter wheat.. 
11.8 
11.3 
1.8 
6.0 
14.8 
10.7 

8.1 
i Winter wheat winterkilled and was reseeded to Marquis on the green-manure plats in 1917 and on all 
four plats in 1920, 1922, and 1923. 
