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PRINCIPLES OF AGRICULTURAL CHEMISTRY 



largely on the size of the crop, requires little discussion. The 

 plant food removed varies largely with the kind of crop. The 

 following figures show the relative amounts of plant food re- 

 moved by a portion of different crops. These figures are from 

 average values ; indivdual analyses may vary somewhat. 



The quantity of plant food removed by the marketed portion of 

 various crops of the size named, 1 is as follows : 

 POUNDS OF PLANT FOOD. 



Loss in By-Products. The by-products consist of the straw, 

 chaff, cottonseed, etc., and the loss of plant food depends upon 

 how they are disposed of. If they are removed, and sold, or 

 otherwise taken away, all the plant food in them is lost. If 

 burned and the ashes returned to the soil, the nitrogen is lost. If 

 turned under, the loss is much less. If made into manure, which 

 is afterwards placed in the soil, there is still some loss. 



PLANT FOOD IN BY-PRODUCTS OF THE CROPS IN PRECEDING TABLE. 



1 Bulletin No. 125, Texas Station. 



2 A portion of this nitrogen comes from the air. 



