FERTILIZERS. 37 



slum? How many pounds to supply the nitrogen? Is this a well bal- 

 anced fertilizer for corn? 



2. Ordinary complete fertilizer is made by taking one ton of 

 ground phosphate rock and adding to this one ton of sulphuric acid 

 and two. tons of filler; to this is added a small amount of nitrogen and 

 potassium. How many tons are there in this mixture and how many 

 pounds of potassium and nitrogen if it is a 2-8-2 mixture? What per 

 cent of the weight could be saved upon which freight is paid if the filler 

 and sulphuric acid are left out? 



It has been estimated that there are at least 5 billion tons 

 of high grade natural phosphate rock in the United States found 

 principally in Tennessee, South Carolina, and Florida, and that 

 there are still more extensive deposits of lower grade phosphate 

 found in a number of other states. 



According to circular 165 of the University of Illinois Agri- 

 cultural College, fine-ground natural rock phosphate can be 

 delivered at the farmers' railroad stations, in most parts of the 

 corn belt, for less than $8.00 per ton. 



Long continued investigations have clearly established the 

 fact that phosphorus can be liberated as needed from the fine- 

 ground natural rock phosphate if it is plowed under in connec- 

 tion with the decaying organic manures. It is therefore evident 

 that the extra expense of *acidulation of phosphate rocks is 

 wholly unnecessary. 



PROBLEMS. 



1. If 4 tons of a 2-8-2 fertilizer containing one ton of phosphate 

 rock, one ton of sulphuric acid, 132 pounds of nitrogen and 132 pounds 

 of potassium, cost $114, what would be saved by^ buying one ton of 

 phosphate rock @ $7 a ton and 132 pounds of nitrogen @ 15c a pound 

 and 13-2 pounds of potassium @ 5c a pound? 



When a farmer buys a ton of an average commercial 

 fertilizer he buys in reality only about 300 pounds of actual plant 

 food. A cheap fertilizer may have less than that amount while 

 a high grade fertilizer may have as high as 600 pounds. 



Cost of mixing, handling, freight and all things considered, 



* Acidulation is produced 'by mixing phosphates with sulfuric acid. 

 Under the average conditions on a farm this is no longer advocated, 

 for it is neither practical nor profitable according to the statements of 

 some of the best authorities on soils and fertilizers. 



