12 BULLETIN 1306, U. S. DEPARTMENT OF AGRICULTUEE 
the spring or the fall plowing. These results show that fallow is of 
little actual benefit to corn. 
RESULTS PROM BARNYARD MANURE IN ROTATIONS 
A number of rotations to determine the effect of the application 
of barnyard manure are included in the investigations at the Sheri- 
dan Field Station. All but one of these include corn, oats, and 
wheat in varying combinations, two include fallow, and one is alter- 
nate corn and flax. In three rotations the manure is applied just pre- 
vious to the corn crop, in one just previous to the oats, in one pre- 
vious to the wheat crop, and in two rotations it is applied just before 
plowing for fallow, which is followed in one rotation by wheat and in 
the other by oats. 
During the period covered by this report each plat in the 2-year 
rotations was manured three times and in the 3-year rotations twice. 
All plats in the 4-year rotations were manured once and part of them 
twice. The first crop following the manure in the 4-year rotations in 
1922 and 1923 was on land manured the second time. 
With wheat no effect from the manure can be discerned when com- 
pared with the crop grown under conditions otherwise similar but 
without the application of manure. Oats apparently show a slightly 
increased yield on manured fallow and when the manure is applied 
directly before the oat crop. The yield of stover appears to be 
slightly increased when the manure is applied directly to the corn 
crop, but no difference has been shown in the grain yield. No effect 
beyond the year the manure is applied can be observed with any 
crop. It should be borne in mind that these experiments were begun 
on new land and that the results from the use of manure may not be 
evident as soon as on land that has been cropped for a number of 
years. 
RESULTS WITH GREEN MANURE COMPARED WITH THOSE ON FALLOW 
To determine the effect on yields and on the humus content of the 
soil, experiments were instituted in which winter rye, field peas, and 
sweet clover are grown and plowed under for green manures. 
At Sheridan this group of experiments is confined to 4-year rota- 
tions in which a green-manure crop is plowed under on each plat 
every four years. The crops in the other three years are wheat, 
corn, and oats. In one set of rotations wheat follows the green 
manure and oats follow corn, and in another set the order is reversed. 
With rye and field peas both winter-wheat and spring-wheat rota- 
tions are included, but with sweet clover only the winter-wheat 
rotations are used. For comparison with the green-manure rota- 
tions there are similar rotations containing bare fallow. The green 
manure is fairly comparable with the fallow, in that each of them 
involves the loss of the use of the land for one year. The green- 
manure plat after plowing is treated the same as fallow for the 
remainder of the season. The green manure is essentially a modified 
fallow, requiring the extra expense of seed and. seeding. 
No effect on yield, other than the effect of the partial fallow, that 
can be attributed to the green manure can be noted with any crop, 
whether immediately following the green manure or later in the rota- 
tion. Yields generally are no greater than on bare fallow. Spring 
