66 KNAPP METHOD OF GROWING COTTON 



fertilized. In this way the benefits from the 

 fertilizers will be cumulative. 



16. If nitrogen-gathering crops are grown 

 and manures and waste matter about the farm 

 plowed under and incorporated with the soil, 

 the mechanical condition will be greatly im- 

 proved and little nitrogen (the most expensive 

 element in fertilizers) will have to be purchased. 



17. Where cotton has been grown exclu- 

 sively on lands for a long period, a complete 

 fertilizer is necessary, but where rotation has 

 been practised only two of the elements and 

 sometimes but one will have to be purchased. 

 The actual field experiments of the individual 

 farmer will be necessary to determine what 

 elements are required. A close study of these 

 problems by the farmer will save money now 

 uselessly squandered on commercial manure. 



