212 THE FIRST BOOK OF FARMING 



By following this method of buying the raw ma- 

 terials and mixing them on the farm, the farmer can 

 reduce his fertilizer bill by quite a considerable 

 amount and at the same time can obtain just the 

 kinds and proper amounts of plant foods needed by 

 his crops. 



KIND AND AMOUNT TO BUY 



The farmer should make the best use of farm 

 manures and through tillage to render plant food 

 available for his crops before turning to commercial 

 fertilizer for additional plant food. 



If he grows leguminous crops for green manur- 

 ing, for feeding stock or for cover crops, he can 

 in many cases secure, chiefly through them, suffi- 

 cient high priced nitrogen for the needs of his crops, 

 and it is necessary only occasionally to purchase 

 moderate amounts of phosphoric acid, potash and 

 lime. 



For special farming and special crops it may be 

 necessary to use the commercial fertilizer more 

 freely. 



It is impossible to say here just what amounts or 

 what kinds of fertilizer should be purchased, because 

 no two farms are exactly alike as to soil, methods 

 of cropping or methods of tillage. 



There are certain factors, however, which will 

 serve as a general guide and which should be con- 

 sidered in determining the kind and amount of fer- 

 tilizer to buy. 



