132 FERTILIZERS 



albuminoids of plants, the casein of milk, and the fibrin of the 

 blood, it is essential to both animal and vegetable life. It is found 

 in fertilizers in three forms: (1) in the form of a nitrate; (2) in the 

 form of ammonia; (3) in the form found in organic matter. 



Nitrates. The most common nitrates are nitrates of soda, 

 potash, and lime. Nitrate of soda consists of one part by volume 

 of sodium, one part of nitrogen, and three of oxygen. It is found 

 in vast quantities in the rainless regions of South America and espe- 

 cially in some portions of Chile. Nitrate of soda is easily dissolved 

 in water and when in solution becomes immediately available for 

 the use of plants. It is especially valuable for early and quick- 

 growing crops on light, sandy soils. On account of the extreme 

 ease with which it dissolves it is not advisable to apply nitrate of 

 soda as a fertilizer to the soil in the fall or too early in the spring. 



Nitrogen in Ammonia. Ammonia gas consists of one part of 

 nitrogen to three parts of hydrogen. It develops more or less in 

 stable manure and can be detected by its characteristic odor. 

 Ammonia readily combines with acids to form salts, the princi- 

 pal ones being ammonium sulphate, ammonium nitrate, and 

 ammonium chloride. Sulphate of ammonia contains hydrogen, 

 nitrogen, sulphur, and oxygen. It is a by-product from the 

 manufacture of illuminating gas, from the distillation of refuse 

 animal matter, and from the manufacture of bone black. 

 Ammonium sulphate is very rich in nitrogen, containing about 

 20.5 per cent of this element. When used on soils containing 

 clay or clay loams, it is found very beneficial. 



Organic Nitrogen. This is composed of both animal and vege- 

 table matter and is derived from a variety of sources. It is found 

 in dried blood and dried meat obtained as waste products from 

 packing houses; in tankage, which is the dried refuse from 

 slaughter-houses and large packing plants, which contains. skin, 

 bone, hair, and meat particles; in dried fish, a waste product from 

 fish-canning establishments; in leather meal and horn meal; in 

 castor pomace, or the refuse from the castor bean after the oil has 

 been extracted ; and lastly, in cotton-seed meal. These fertilizers 

 may be applied in large quantities and at any time. 



Potash Fertilizers. Prior to 1860 all potash fertilizers were 

 obtained from wood ashes and stable manure. Since that time 



