PHOSPHORUS 185 



phorus shipped off from American farms in animal products is 

 returned to the soil in bone fertilizers. The mineral matter in bone 

 consists chiefly of tricalcium phosphate, with a small amount of 

 calcium carbonate. There is practiced more or less adulteration 

 of bone fertilizers by admixture of raw rock phosphate or acid 

 phosphate. 



There are three principal forms of bone meal'offered for sale 

 (i) raw bone, (2) steamed bone, and (3) acidulated bone. 



Raw bone meal. Raw bone meal contains about 9 per cent of 

 phosphorus, 4 per cent of nitrogen, and much organic matter, 

 including more or less fat, which tends to retard decomposition. 

 The most common application of bone or other ordinary commercial 

 fertilizer is 200 pounds per acre. Since 9 per cent means 9 pounds 

 per hundred, this application would amount to 18 pounds of 

 phosphorus per acre, or one pound more than is contained in 

 100 bushels of corn. Since 200 pounds is one tenth of a ton, raw 

 bone meal contains about 180 pounds of phosphorus per ton. 



Hence, the rule: To convert per cent into pounds per ton, 

 double the per cent and add one cipher. It is always advisable to 

 memorize pounds per ton and to think in those amounts, rather 

 than in per cent. At 10 cents a pound for phosphorus and 15 

 cents for nitrogen, a ton of raw bone meal costs about $30, which is 

 $18 for the phosphorus and $12 for the nitrogen. 



Nearly i| tons of raw bones are required to make one ton of 

 steamed bones, the loss in weight consisting of fat, flesh, glue, and 

 other organic matters rich in nitrogen. 



Steamed bone meal. Steamed bone meal contains from 12 

 to 14 per cent of phosphorus, and it should average at least 12^ 

 per cent, or 250 pounds of phosphorus per ton, costing $25 at 

 10 cents a pound for the element phosphorus. Thus, 200 pounds 

 of steamed bone per acre supplies 25 pounds of phosphorus, or 

 two pounds more than is required for a hundred-bushel crop of 

 corn (grain and stalks). By steaming bones the nitrogen is largely 

 removed in the organic matter, only about .8 per cent, or 16 pounds 

 per ton, being found in good steamed bone, an amount within the 

 legal limits of error in some fertilizer laws, and too small to justify 

 consideration in the purchase price, especially when nitrogen can 

 be secured from the inexhaustible supply in the air by using leg- 



