ROTATION AND CULTURAL METHODS AT EDGELEY, N. DAK. 15 
the humus content of dry-land soils, thus increasing the yields. It 
was argued that they could be used in extensive or exclusive grain 
farming where barnyard manure was not available in adequate 
quantity. 
Experiments were instituted to determine the effect of using 
winter rye, field peas, and sweet clover for green manures. At the 
Edgeley station this group of experiments was confined to 4-year 
rotations in which the land is green manured once every four years. 
The crops in the other three years are wheat, oats, and corn. Each 
green manure is used in two rotations. In one rotation oats follow 
the green manure and the wheat is after corn, which follows the oats. 
In the other the wheat follows the green manure and the oats are on 
corn ground. 
Rotation No. 14 is rye for green manure, oats, corn, and wheat ; 
rotation No. 15 is rye for green manure, wheat, corn, and oats; rota- 
tion No. 16 is peas for green manure, oats, corn, and wheat ; rotation 
No. 17 is peas for green manure, wheat, corn, and oats ; rotation No. 
32 is sweet clover for green manure, oats, corn, and Avheat ; and rota- 
tion No. 31, is sweet clover for green manure, wheat, corn, and oats. 
The sweet clover in these rotations is sown with the preceding wheat 
or oats and plowed under when in blossom in its second year. 
For comparison with these green-manure rotations are two similar 
ones having bare fallow in place of the green manure. These are 
rotations Nos. 18 and 19, already described. In rotation No. 18 the 
wheat is on fallow and the oats on corn ground, and in rotation No. 
19 the oats are on fallow and the wheat on corn ground. 
The green-manure rotations are fairly comparable with the fallow 
rotations in that each of them involves the loss of the use of the land 
for one year in four. After the green-manure crop is turned under 
the plats are treated as fallow for the remainder of the season. They 
are essentially modified fallows, requiring the extra expense of seed 
and seeding. 
Rotations Nos. 14, 15, 16, and IT were started in 1906 and the other 
four in 1907. 
The results are difficult to determine in all their relations, on 
account of the natural variations in plat yields. The study at the 
present time is further complicated by the fact that the last period 
of four years has been one of low yields and two of the four have 
been bad rust years. With all their discrepancies and apparent 
contradictions, however, they point to a general conclusion : The 12- 
year averages from 1908 to 1919, inclusive, afford no basis of hope to 
increase yields by the use of green manures. One possible exception 
to this will be considered farther on. The expense of the green 
manures precludes all possibility of their profitable employment. 
Further, when a crop is grown there is no basis of justification for 
plowing it under in the hope of increasing the yield of succeeding 
crops. 
