254 SOILS 



Working from percentages. Often the per cent, of 

 phosphoric acid, nitrogen and potash suitable to a crop 

 is given. In what quantities shall given fertilizing ma- 

 terials be mixed so as to supply a fertilizer possessing 

 these percentages? 



PROBLEM III: How many pounds each of acid 

 phosphate, sulphate of ammonia, and kainit will be needed 

 to make an 8 3 3 fertilizer? 



Process In 100 pounds. In one ton 



Phosphoric acid 8 per cent 8 160 



Nitrogen 3 per cent 3 60 



Potash 3 per cent 3 60 



Acid phosphate 14 per cent, or 14 pounds in 100. To 

 get 160 pounds divide 160 by .14== 1, 142-4-. 



Sulphate of ammonia 20 per cent, or 20 pounds in 100. 

 To get 60 pounds divide 60 by .20 = 300. 



Kainit 12.5 per cent, or 12.5 pounds in 100. To get 

 60 pounds, divide 60 by .125 = 480. 



We have now: 



Acid phosphate 1,142+ pounds 



Sulphate of ammonia 300 pounds 



Kainit 480 pounds 



Total 1,922 pounds 



Unfurnished 78 pounds 



2,000 pounds 



The remaining 78 pounds may be supplied in fine sand, 

 road dust, or in any such material. 



If the reader considers his fertilizing problems in a 

 careful way as suggested here, he will have no difficulty 

 in mixing his own materials, and he will be pleased most 

 certainly with the results. 



