COTTON 129 



being from 6 to 8 per cent of the former and 7 to 9 

 per cent of the latter. 



Cotton Seed Meal: Contains 7 per cent of 

 nitrogen, or 140 pounds to the ton, and is the most 

 important of the vegetable products used in 

 commercial fertilizers. It decays very rapidly but 

 lasts for a considerable length of time. It is much 

 less quickly available than nitrate of soda or 

 sulphate of ammonia, and more promptly available 

 than tankage. 



PHOSPHORUS 



Experiments tend to show that phosphorus is the 

 chief element demanded by most cotton soils. As 

 is true of nitrogen, so phosphorus is necessary to 

 the full and complete development of all parts of 

 the plant, but its usual use is in fruit and seed 

 production. Being a mineral substance, a de- 

 ficient supply in the soil can be reinforced only 

 through artificial means. 



SOURCES OF PHOSPHORUS 



Phosphatic Rock: These are mined in North 

 and South Carolina, Tennessee, Georgia, and 

 Florida. They must be ground finely before being 

 used, and even then are slow to decay. Best 

 results are obtained by treating the ground rock 

 with sulphuric acid to make the phosphoric acid 

 available. 



These materials make up the bulk of the phos- 

 phorus supply in cotton fertilizers. They contain 

 from 12 to 16 per cent of available phosphoric 

 acid. 



Bone Fertilizers: Bone was early used as a 

 fertilizer and is still popular today. "Ground 



