270 



SOILS 



ground. Thus corn, a relatively shallow feeder, should 

 follow clover, a deep penetrator, or some crop like it that 

 sends its roots down deep into the soil. This plan gives 

 the deep grower an opportunity to strike deeply into the 

 soil : to open the tightly bound subsoil, that air and water 

 may get in to release plant food and to hand it over to 

 succeeding crops. For this reason land 

 seeded to a crop like clover makes fine 

 wheat, corn or cotton the next season. 



Study the feeding habits of plants, 

 then. Study their roots : learn where 

 they grow, how deep they go. Do they 

 plunge deep into the soil? or do they 

 skim along in the surface layer near to 

 air and light? Ask these questions and 

 investigate. The knowledge is practical ; 

 it is light upon a basic principle of suc- 

 cessful farming; and in the future the 

 root systems of cultivated crops will get 

 more attention and study than the past 

 has allotted to them. 



Plants vary as to taste. There is a 

 wide range in kinds of foods that plants 

 fancy. For instance, the potato relishes 

 potassium in abundance ; corn and wheat 

 do best when a great deal of nitrogen is 

 in the soil ; all grain crops must have 

 much phosphorus and potassium to make 

 well-filled heads. So crop rotation enables each crop to 

 find its favorite dish. All of the legumes get their nitro- 

 gen from the air; they also send their roots down into the 

 subsoil, where the mineral elements are, and these the 

 roots gather up and bring nearer to the top. The crops 

 then are harvested just in time for other crops; for in- 



COW-PEA 

 ROOTS 



They secure ni- 

 trogen, and 

 at the same 

 time subsoil 

 the land 



