382 THE SMALL GRAINS 



nitrogen, in free ammonia, is the substance most easily 

 lost. Piling manure loosely causes bacterial action and 

 hence loss of free ammonia. It is best, therefore, to leave 

 the manure in the corral or stable until it can all be 

 hauled and spread directly on the ground and plowed 

 under ; or if it must be removed, it should be piled com- 

 pactly in a shady place, and occasionally moistened. If 

 possible, the stable or corral should be cleaned during wet 

 weather. Every means possible should be taken to keep 

 the manure moist and to keep air out of it until finally 

 used. Where both cattle and horse manure are produced, 

 the latter may be put into proper condition more quickly 

 by mixing the two, occasionally wetting the manures 

 afterward. Sheep manure should not be put upon the 

 land until it has rotted for at least six months (Headden 

 and Douglas, 1910, pp. 30-31). Because of the prev- 

 alence of winter rains, it may be better always to 

 apply manure in the fall or winter rather than in the 

 spring. 



411. Green-manuring. Under present conditions the 

 most practicable means of increasing the soil humus in 

 any considerable acreage of land, in this area, is by the 

 use of green-manures. Green-manure crops and the 

 arrangement of rotations so as to introduce such crops 

 will always be of prime importance. It is true that in 

 the Great Plains in only a few places have green-manures 

 given profits above the cost of cropping, if we exclude 

 possible residual effects upon the soil (370) ; but results 

 of investigations to date appear to show greater gains in 

 yields of cereals after green-manure crops over those in 

 continuous cropping, and better adaptation of the green- 

 manure crops themselves in this area than in the Great 

 Plains. 



