130 SOILS AND FERTILIZERS 



Under some conditions, as forcing a crop on an im- 

 poverished soil, sodium nitrate is desirable. Under 

 other conditions tankage, cottonseed cake, or some 

 other form of nitrogen may be made to answer the 

 purpose. There is annually expended in purchasing 

 nitrogenous fertilizers a large amount of money which 

 could be expended more ecomically, if the science of 

 fertilizing were given a more careful study. The 

 uses of nitrogenous fertilizers for special crops and 

 the testing of soils to determine any deficiency in 

 nitrogen are discussed in Chapters X and XI which 

 treat of commercial fertilizers and the food require 

 ments of farm crops. 



