28 



COTTON CULTURE 



taken from official sources and is thoroughly reliable. 

 It is based on the growth of one hundred pounds of lint 

 showing the amounts, of plant-food elements removed 

 from the soil. 



It is evident from this analysis that a crop of 100 pounds 

 of lint will remove from the soil 13.06 pounds of potash, 

 8.17 pounds of phosphoric acid, and 20.7 pounds of nitro- 

 gen. . Yet the proportions found by analysis are not 

 found to give the best results in actual practice; because 

 account must be taken of the great losses that occur through 

 heavy washing rains which remove plant food from the 

 soil; also, that nitrogen is sometimes lost by the action 

 of bacteria, as may be noticed in the decomposing manure 

 pile, while phosphoric acid is likely to become "unavail- 

 able" in the soil through its tendency to take insoluble 

 forms when brought into contact with lime and other 

 materials existing in the natural soil. For this reason it 

 is well to use more fertilizer than just what is shown to be 

 needed by the chemical analysis of the crop. 



