SYSTEMS OF CROPPING 89 



1. They help to hold soil from washing away by heavy 

 rains. 



2. Their roots are helpful to unlock plant-food in the soil. 



3. When members of the clover family of plants, called 

 legumes, are used, they gather nitrogen from the air and add 

 it to the soil for future crops. 



Fig. 48. — Crimson (or scarlet) clover. This is a hardy legume, chiefly used as a 

 winter cover crop. It is sown in fields of corn, cotton, or other crops and in orchards 

 in July or August. It will improve the soil while growing until the following spring. 

 It may then be cut for hay or may be plowed under for green manure. 



4. They check the growth of bad weeds. 



5. They furnish pasture, hay or other valuable stock feed. 



6. If plowed under as green manure, they produce humus 

 in the soil, and quickly give to the soil the plant-food they 

 have been using. 



7. When grown among fruit trees and shrubs they check 

 late growth of the trees and temper the effect of winter 

 freezing. 



