SOILS 121 



hauled off. It may be assumed that the roots and stubble 

 of the clover and alfalfa contain no more nitrogen than was 

 furnished by the soil for those crops, but that the nitrogen 

 contained in the hay harvested may represent new nitrogen 

 taken from the air. With the information thus far secured 

 this is a reasonable basis to figure on for soils of moderate 

 productive power. 



For the grain and hay farmer this rotation may well be 

 modified by substituting wheat for the first corn crop, thus 

 growing wheat, corn, oats, and clover in the four-year rota- 

 tion, and alfalfa on the fifth field. If only the grain, clover 

 seed, and the alfalfa hay are sold, all stalks, straw, and clover 

 (except the seed) being returned to the land, the nitrogen 

 and organic matter may be maintained by the grain and hay 

 farmer, provided a cover crop of clover is also seeded on the 

 wheat ground in the spring to be plowed under late in the 

 following fall or sufficiently early the next spring so as to 

 get the land in good shape for corn. 



Where there is no permanent pasture land, the live-stock 

 farmer may seed both clover and timothy with the oats, and 

 then use the field two or three years for meadow and pas- 

 ture, thus making a six-field or seven-field system. With 

 some modifications, a system of mixed farming may be prac- 

 ticed in which some crops are sold and others fed to live 

 stock. 



NOTEBOOK QUESTIONS 



1. Why is the soil our greatest natural resource? 



2. List the agencies active in the formation of the soil. 



