CONSERVATION OF FERTILITY 



287 



No stock is kept, the straw is burned, and the ashes 

 are wasted. In addition to the nitrogen removed in 

 the crops other losses must be considered. Experiments 

 show that when exclusive grain farming is practiced, 

 for every pound of nitrogen removed in the crop, 4 

 pounds are lost from the soil in other ways. This would 

 make the total loss of nitrogen over 28,500 pounds, 

 or 177 pounds per acre, which large as it may seem 

 is the actual loss from the soil when grain only is raised 

 and it is sold. Experiments at the Minnesota Experi- 

 ment Station with a soil that had been cultivated 40 

 years, showed the annual loss per acre of nitrogen in 

 exclusive wheat raising to be 25 pounds through the 

 crop and 146 pounds due to oxidation of the nitroge- 

 nous humus of the soil. 9 



EXCLUSIVE GRAIN FARMING 

 Sold from the Farm 



When exclusive grain farming was followed, the annual 

 losses of fertility from this farm of 160 acres were 28,500 



