Food for Nitrogen Phos. Acid Potash 



Plarts Ibs. Ibs. Ibs. 



" Nitrate of Soda 200 Ibs. x .15 = 30 



Tankage 200 Ibs. x .05 = 10 



Tankage 200 Ibs. x .10 = . . 20 



Acid Phosphate 1000 Ibs. x .16 = . . 160 



Sulphate of Potash 200 Ibs. x .50 = . . . . 100 



Total.. ..40 180 100 



A ton of the mixture would thus contain 40 pounds 

 of Nitrogen, 180 pounds of phosphoric acid and 100 

 pounds of potash. To get the weight per hundred we 

 divide each of these amounts by 20, obtaining a formula 

 that may be represented by 2-9-5. 



To Calculate the Value of Mixed Fertilizers. 



When acid phosphate with 16 per cent, available 

 phosphoric acid can be bought at $15.50 per ton; when 

 sulphate of potash with 48 per cent, of potash can be 

 bought at $50.00 per ton, and when Nitrate of Soda 

 containing 15 per cent, of Nitrogen can be bought at 

 $52.00 per ton; what would be the value of a mixed 

 fertilizer guaranteed to contain 6 per cent, of available 

 phosphoric acid, 5 per cent, of potash, and 3.25 per cent, 

 of Nitrogen? 



As a preliminary step we have to determine the 

 cost per pound of the constituents in the straight fer- 

 tilizers. Thus: 



2000 Ibs. of Nitrate of Soda x .15 = 300 Ibs. available Nitrogen 

 l.OO divided by 300 Ibs. = $0.173 per Ib. 



2000 Ibs. of Acid Phosphate x .16 = 320 Ibs. Phosphoric Acid 

 $15.50 divided by 320 Ibs. = $0.048 per Ib. 



2000 Ibs. of Sulphate of Potash x .48 = 960 Ibs. actual Potash 

 l.OO divided by 960 Ibs. = $0.052 per Ib. 



Next comes the determination of the total plant- 

 food in the mixed fertilizer. Thus:- 



