FERTILITY AND HUMUS IN DRY AREAS 423 



in the case of the sand vetch, it would seem to be quite 

 feasible to sow the seed in conjunction with spring 

 grain without detriment to the grain, and to bury the 

 clover crop the following season, preferably in conjunc- 

 tion with the summer-fallowing of the land. The sweet 

 clover produces a large tonnage relatively for burial, and 

 it gathers and stores in the soil relatively large amounts 

 of nitrogen. Moreover, it will succeed on soils so strong- 

 ly impregnated with alkali as to preclude the possibility 

 of growing on them the more valuable plants with any 

 measure of success. In this way such soils may be im- 

 proved by the removal of considerable quantities of the 

 alkali, should the crop be removed, and by the favor- 

 able influence exerted on the soil mechanically should it 

 be buried. Ordinarily the cow pea, the sand vetch and 

 sweet clover should be buried when in full bloom. 



