CORN 



165 



relationship to these conditions. The trials thus far con- 

 ducted have given best results with depths of four to 

 six inches. In the humid regions, deeper plowing has 

 been more successful than in the arid regions. 



Subsoiling 1 is nowhere a common practice. Many 

 trials of it have shown it to be unprofitable, with rare 

 exceptions. 



In case one wishes to deepen the soil, it should not be 



done all at once. If sev- 

 eral inches of the raw 

 subsoil are turned up, 

 it will injure the first 

 few crops. It is better 

 to plow one inch deeper 

 each year until the de- 

 sired depth is reached. 

 In semi-arid regions the 

 subsoil is usually not so different from the surface soil. On 

 many soils the depth should be varied from year to year, 

 otherwise a hard layer may form where the plow runs. 



When several teams are plowing on the same land, the 

 plows should all be set at the same depth. If one plow runs 

 an inch deeper than the 

 others, it is much harder 

 for this team than it 

 would be if all plows 

 ran at the same depth. 



1 Subsoiling is the break- 

 ing up of the subsoil in the 

 bottom of the furrow without 

 bringing the subsoil to the sur- 

 face. The subsoil plow follows F ?4 Buckwheat on land that waa 



P m Same Fig ' 73 



FIG. 73. Buckwheat on land that was 

 plowed early and well fitted 



