164 COBN CROPS 



There are no experiments to show the ultimate effect 

 of following a system of continuous shallow plowing or 

 continuous deep plowing, but practical experience has 

 shown that land should be occasionally plowed deep 

 (8 inches) to keep the sm-face in best mechanical 

 conditions. Heavy soil requires deep plowing more 

 often than do light soils. Probably a very heavy soil 



Fig. 42. — Plowing under alfalfa sod in preparation for corn. 



should be plowed deep once each year, while certain light 

 soils, especially where rainfall is low, do very well with 

 deep plowing every two or three years. 



Hunt 1 summarizes certain experiments with deep and 

 shallow plowing as shown on the following page. 



It has been demonstrated many times, that if the soil 

 has been kept in a good productive condition, that the 

 preparation immediately before planting or even the 

 system of cultivation after planting is not likely to have 

 an important effect on the yield of the current crop. The 

 crop secured does not depend so much on treatment of 



' Hunt, Thos. F. Cereals in America, p. 220. 



