I5O SOILS AND FERTILIZERS 



pounds per acre is a safe dressing, 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 impov- 

 erished soil more may be used than on soils which are 

 for various reasons out of condition. The cost of the 

 nitrogen as tankage is determined from the composi- 

 tion and selling price. If tankage containing 7 per 

 cent of nitrogen and 12 per cent of phosphoric acid is 

 selling for $32 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. Sup- 

 pose bone phosphoric 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 

 $22.40. The 140 pounds of nitrogen in the ton of fer- 

 tilizer would be worth $22.40, or 16 cents per pound. 

 In eastern markets the price of tankage is usually higher 

 than near the large packing houses of the West. 



166. Flesh Meal. - - The flesh refuse from slaughter- 

 houses is sometimes kept separate from the tankage 

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

 removed and used for the manufacture of glue and 

 soap. Flesh meal is variable in composition and may 

 be very slow in decomposing. It contains from 4 to 8 

 per cent or more of nitrogen, with an appreciable amount 

 of phosphoric acid. Occasionally it is used for feeding 

 poultry and hogs, and cattle to a limited extent. The 



