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CHEMISTRY OF FARM PRACTICE 



4. Given the high-grade materials; reduce to the pro- 

 portion of a low-grade formula and avoid the use of a 

 filler. 



5. To determine the amount and composition of a 

 fertilizer when a portion is used under the crop and the 

 remainder as a side application or topdressing. 



6. To convert a fertilizer from one formula to another. 

 Examples of each form of calculation are given as 



types of the work involved. 



In the fertilizer trade, the term unit is often used. A 

 unit is 1 per cent of a ton, or 20 pounds. In making these 

 calculations, it must be remembered that per cent means 

 pounds in a hundred pounds of material. 



(1) The percentage and weight of material being given, 

 calculate the formula. 



PROBLEM: Given, 1000 pounds of 16 per cent avail- 

 able acid phosphate (P2Os), 100 pounds of muriate of potash, 

 48 per cent water-soluble potash (K2O) and 900 pounds of 

 cottonseed meal that will analyze nitrogen equivalent to 

 7 per cent ammonia (NHs),2per cent phosphoric acid (P2O5) 

 and 1.5 per cent of water-soluble potash (K^O). 



A good way to outline this calculation is as follows: 



