CHAPTER V 

 COMMERCIAL FERTILIZERS AND SOIL AMENDMENTS 



COMMERCIAL FERTILIZERS 



What is meant by commercial fertilizer. The term com- 

 mercial fertilizer has already been used several times in 

 discussing plant food. It always refers to those substances 

 containing nitrogen, phosphoric acid and potash, which are 

 bought and used as fertilizer. A complete fertilizer is one 

 that contains all three of these components nitrogen, 

 phosphoric acid and potash. Its composition is generally in- 

 dicated by figures representing the available amounts of the 

 three ingredients as shown by a chemical analysis, and is 

 expressed in percentage. 



The order is always (i) nitrogen; (2) phosphoric acid; 

 (3) potash. For example, a 2-8-4 fertilizer is one contain- 

 ing 2 per cent nitrogen, 8 per cent phosphoric acid, 4 per 

 cent potash. 



The production of commercial fertilizers has become a 

 large industry in this country. The annual sales in normal 

 times amount to over $100,000,000, most of this amount 

 being spent for complete fertilizers. In many states the sale 

 is regulated by law. A chemical analysis of each brand is 

 required, and thi guaranteed analysis must be made public. 

 It must appear on each package of fertilizer for sale, usually 

 on a tag attached to the package, and may be printed in a 

 bulletin or circular for free distribution. In this way both 



39 



