134 FERTILIZERS 



Mineral phosphates form what is known as phosphate rocks. In 

 the provinces of Ontario and Quebec in Canada there is a species 

 of phosphate rock called apatite which frequently contains as high 

 as 40 per cent of phosphoric acid. Large beds of phosphate rock 

 are also found in North Carolina, South Carolina, Florida, and 

 Tennessee, and these deposits vary in thickness from one to twenty 

 feet. This form is known as land rock or land phosphate. Some- 

 times small nodules of mineral phosphates are found in river beds 

 and are called river rock or river phosphates. Carolina phosphates 

 contain from 26 per cent to 28 per cent of phosphoric acid. They 

 were first worked in 1868. 



The presence of phosphates in Florida was first discovered in 

 1888 and since then they have been mined extensively. A good 

 phosphate bed is often more valuable than a gold mine. The 

 Florida phosphates occur in three well-defined forms: (1) soft 

 phosphate, containing from 18 to 30 per cent of phosphoric acid; 

 (2) pebble phosphate, containing frequently as high as 40 per 

 cent of phosphoric acid; (3) bowlder phosphate, often containing 

 40 per cent or more of phosphoric acid. 



Iron Phosphate is produced in large quantities in England, 

 France, and Germany and is a waste product obtained in the 

 manufacture of steel from phosphatic ores. It is usually put on 

 the market in the form of a fine powder and contains from 15 to 

 20 per cent of phosphoric acid. ' It is highly recommended as a 

 fertilizer for clay and sandy soils. 



Guano Phosphate is obtained from the guano deposits found 

 in South America and the rocky islands fringing the Pacific 

 coast, and it is very rich in phosphoric acid and nitrogen. It is 

 also found in the West Indies, but the greater part of the world's 

 supply comes from the Peruvian coast. Guano consists of the 

 manure and the dead bodies of certain fish-eating fowls that 

 hatch and bring up their young in the rocky islands of the Pacific 

 near Peru. 



Manufacture of Commercial Phosphates. The phosphates as 

 found in nature are practically insoluble and cannot be used as 

 plant food or fertilizers until subjected to certain treatment. 

 Generally sulphuric acid is added to the pulverized phosphate, 

 which converts it into acid phosphate containing three kinds 



