72 COTTON CULTURE 



rock, dissolved bone-black, etc. Acid phosphates are 

 formed by treating some form of insoluble phosphate, as 

 rock phosphate, bone, bone-ash, etc., with sulfuric acid. 

 By this treatment there are formed soluble phosphates 

 of lime and gypsum (sulfate of lime) in nearly equal 

 proportions. 



MATERIALS SUPPLYING NITROGEN 



Nitrate of Soda, known as "Chili saltpeter," is found 

 in large deposits which have been formed in the rainless 

 regions of Chili and Peru. 



Sulfate of Ammonia is formed from waste materials 

 produced in the manufacture of gas or coke. 



Whole Cotton Seed is rather slow in becoming avail- 

 able as a fertilizer. By rotting to "kill" the seed it is 

 made more effective. The common practice is to pile in 

 large heaps and leave standing for several months. This 

 not only kills the seed, but also prevents the injurious 

 action sometimes observed from using raw seed as manure. 

 But a farmer cannot afford to use sound cotton seed as a 

 fertilizer. The seed should be exchanged for cotton-seed 

 meal. 



Cotton- Seed Meal is the product formed by removing 

 the oil from cotton seed by pressure, after which the ma- 

 terial is dried and ground. The hulls of the cotton seed 

 also possess some fertilizing value. 



Tobacco Stems are the refuse from tobacco factories. 



Dried Blood consists of blood obtained from slaugh- 

 tering animals. It is prepared for market by coagulating, 



