342 THE SMALL GRAINS 



present but not available. There is in addition to be 

 considered the probable improved physical condition of 

 the soil that will result from an increase in humus. At the 

 Edgeley, North Dakota, substation, in 6 years of experi- 

 ments in applying manure to fallow followed by a cereal 

 crop, there was an average increase of yield of oats fol- 

 lowing the manured fallow of 3.4 bushels to the acre, 

 though in 2 years of the 6 the unmanured land gave the 

 higher yields. Wheat on the manured fallow averaged 

 3.6 bushels to the acre more than on the unmanured 

 fallow, with some increase over the latter each year. 

 Corn grown the second year after the fallow yielded an 

 average of 760 pounds more to the acre after manured 

 than after unmanured fallow. There was an apparent 

 residual effect upon oats 3 years after the manuring, 

 causing an average increase of 5.9 bushels to the acre, 

 but no such residual effect upon wheat (Thysell, McKin- 

 stry, Towle, and Ogaard, 1915, pp. 188-189). 



369. Green-manures. Results would be expected 

 from green-manuring rather similar to those secured in 

 the use of barnyard manures in the Great Plains. Un- 

 fortunately, very little more investigation has been made 

 of the former than of the latter subject. Green-manures 

 would seem to be even more important in this region as a 

 source of humus than in the Eastern area, as there are no 

 pasture or meadow crops to turn under except where brome- 

 grass is grown, and field cropping is so extensive that the 

 quantity of barnyard manure available is usually insig- 

 nificant. . Brome-grass has not filled the need of a drought- 

 resistant meadow grass to the extent that was expected. 

 In the northern portion of the area, rye and field peas are 

 probably the best green-manure crops, while rye and cow- 

 peas may be used in the southern portion. Sweet clover 



