128 NATURE STUDY REVIEW [10:4— April, 1914 



At $42.00 per ton one pound of muriate of potash will cost 

 2.1 cents (42 X 100 -i- 2000 = 2.1). 120 pounds will cost $2.52 

 (120X .021 = 2.52). 



The total cost of materials to prepare one ton of a 4-8-3 ferti- 

 lizer will be $27,195 (11.875 X 12.80 X 2.52 = 27.195). The total 

 number of pounds of these materials needed to make a ton of a 

 4-8-3 fertilizer will be 1762.8. Therefore, 239.2 pounds of filler 

 must be added to bring the mixture up to the 2000 pounds (2000 — 

 1760 = 239.2). In farm practice, however, the fertilizer may be 

 applied at a correspondingly lower rate per acre. In this case 

 about seven-eights of the full amount per acre should be supplied 

 thus saving the trouble of adding a filler. 



Problems: 



1. How many pounds of nitrogen are in one-half ton of nitrate 

 of soda? In this amount of dried blood? Of sulfate of am- 

 monia? 



2. How m.any pounds of phosphoric acid in one and one-half 

 tons of acid phosphate containing 14 per cent phosphoric acid? 

 Containing 16 per cent phosphoric acid? 



3. How m.any pounds of potash in three-quarters of a ton of 

 muriate of potash? In the same am.ount of kainit containing 

 1 2 per cent potash ? 



4. How much each of nitrate of soda, acid phosphate (contain- 

 ing 14 per cent phosphoric acid), and muriate of potash will be 

 required to make a ton of a 1-9-4 fertilizer? How much filler 

 will be needed? 



Estimate total cost based upon $57.50 per ton for nitrate of 

 soda, $16.00 per ton for acid phosphate, and $42.00 per ton for 

 muriate of potash. 



5. Wheat straw contains .6 per cent of nitrogen. What would 

 be the loss in pounds of nitrogen in burning 50 tons of wheat 

 straw ? Calculate the loss in dollars and cents if nitrogen is worth 

 19 cents a pound. 



6. Manure on the average contains .5 per cent of nitrogen. 

 Calculate the value of the nitrogen in 140 tons of m^anure. 



7. The average loss of nitrogen by leaching when manure is 

 in unprotected piles for two m.onths or more is 50 per cent. What 

 would be the value of nitrogen lost in 140 tons of manure kept 

 under such conditions ? 



8. Phosphoric acid in rock phosphate is not immediately avail- 

 able for plant growth but may be made so in a few months by 

 mixing with manure. Rock phosphate containing 12 per cent 



