66 COTTON CULTURE 



an average year the increased yield may be as much as 

 $20 for each $10 worth of fertilizer, or one hundred per 

 cent profit. At the present (1910) high prices of cotton 

 the average profits are much larger. 



GENERAL REMARKS ON FER- 

 TILIZERS 



As several crops of different kinds may be grown in 

 rotation with cotton, it may be useful to give a general 

 review of the best fertilizer practice. All the crops mak- 

 ing part of a rotation must be fertilized, except when a 

 cow-pea, clover, or other leguminous crop is raised. While 

 nitrogen may be secured indirectly as a part of a rotation 

 system through a special property of leguminous crops, 

 potash and phosphoric acid must always be applied direct. 

 It is well known that different crops need different quan- 

 tities of potash, phosphoric acid, and nitrogen compounds. 

 If we cannot depend upon the soil to furnish any consid- 

 erable quantity of plant food, then the farmer must use, 

 at least, the amounts of fertilizing materials' removed by 

 each crop. In the following table we give the number 

 of pounds of potash, phosphoric acid, and nitrogen used by 

 different kinds of crops grown on one acre of land. 



