GROWING LEGUMES FOR SOIL BETTERMENT 101 



too, never to plow the same depth twice in succession. 

 In general, fall plowing should be from 7 to 9 or 10 

 inches and spring plowing from 5 to 7 inches deep. There 

 are special cases in which these rules do not apply, but 

 their discussion would take us too far from the purpose 

 of this chapter. 



We plow the soil in order to loosen up its texture and 

 get air into it ; also to turn under stubble, manure, etc., to 

 make humus. Killing weeds is another object ac- 

 complished by plowing. After a soil has been thoroughly 

 pulverized to great depths, so that there is no danger of 

 turning up packed clay, the deeper the plowing the better 

 the crops. But the cost also increases with depth, so that 

 ordinarily it does not pay to plow more than about 10 

 inches deep. 



Some crops prefer rather a loose seed bed. Millet is 

 such a crop. Farmers sometimes plow a second time in 

 order to sow millet on freshly plowed land. Other crops, 

 such as wheat and alfalfa, prefer a fairly compact seed 

 bed ; hence, frequent harrowing and rolling after plowing 

 is good practice before seeding to these crops. Never- 

 theless, it pays to plow the land for them, even if we have 

 to compact it again before seeding. The plowing aerates 

 the soil and helps to set plant food free. 



