NITROGENOUS MANURES 131 



fertilizer to use for garden purposes. It may also be 

 used as a top dressing on grass lands, and may be 

 spread broadcast on grain lands. It is best to apply 

 the tankage, when possible, a few days prior to seed- 

 ing, and it should not come in contact with seeds. 

 Two hundred and fifty pounds per acre is a safe dress- 

 ing, and when there is sufficient rain to ferment the 

 tankage, 400 pounds per acre may be used. A dressing 

 of 800 pounds in a dry season would be destructive to 

 vegetation. On impoverished soil more may be used 

 than on soils which are for various reasons out of 

 condition. The cost of the nitrogen, as tankage, may 

 be determined from the composition and selling price. 

 If tankage containing 7 per cent, of nitrogen and 12 

 per cent, of phosphoric acid is selling for $22 per ton, 

 what is the cost of the nitrogen per pound ? The 

 market value of phosphoric acid, in the form of bones, 

 should first be ascertained. Suppose that bone phos- 

 phoric acid is selling for 4 cents per pound. The 

 phosphoric acid in the ton of tankage would then be 

 worth $9.60, making the nitrogen cost $12.40. The 

 140 pounds of nitrogen in the ton of fertilizer would 

 then be worth $12.40, or 8.8 cents per pound. In 

 eastern markets the price of tankage is usually much 

 higher than near the large packing houses of the west. 



153. Flesh Meal. — The flesh refuse from slaugh- 

 ter-houses is sometimes kept separate from the tank- 

 age and sold as flesh meal, the fat and gelatin being 



