COTTON FERTILIZERS 389 



LABORATORY EXERCISES 



1. Assuming that nitrogen is worth 17 cents per pound, avail- 

 able phosphoric acid 5 cents, and potash 5 cents, calculate the 

 commercial value of the plant-food in a ton of fertilizer of the 

 following composition : 



(a) 10 per cent available phosphoric acid, 2 per cent nitro- 

 gen, and 2 per cent potash ; 



(6) 10 per cent available phosphoric acid, 3 per cent nitro- 

 gen, and 3 per cent potash ; 



(c) 5 per cent available phosphoric acid, 4 per cent nitro- 

 gen, and 5 per cent potash. 



2. Calculate the percentage of nitrogen, phosphoric acid, and 

 potash in a mixture of 



300 pounds nitrate of soda containing 15 per cent of nitro- 

 gen; 



500 pounds kainit, containing 12 per cent of potash ; and 

 200 pounds of acid phosphate, containing 16 per cent of 

 available phosphoric acid. 



3. Calculate how many pounds of each of the three fertilizers 

 just mentioned would be required to make a mixture containing 

 the same amounts and kinds of plant-food as one ton of guano 

 analyzing 10 per cent available phosphoric acid, 1.8 per cent 

 nitrogen, and 2 per cent potash. 



4. Calculate how many pounds of the same kind of phosphate 

 and kainit as in (2) and of cotton-seed meal containing 2.8 per 

 cent of available phosphoric acid, 6| per cent of nitrogen, and 1.8 

 per cent of potash, would be required to contain the same kinds 

 and amounts of plant-foods as one ton of guano analyzing 10 per 

 cent available phosphoric acid, 2 per cent of nitrogen, and 2 per 

 cent of potash. 



LITERATURE 



NEWMAN, J. S. Ala. Expr. Sta., Buls. Nos. 5, 12, 22. 

 BONDURANT, A. J., and CLAYTON, J. Ala. Expr. Sta., Buls. Nos. 

 34 and 42. 



