MIXING OF FERTILIZERS 167 



The formula is obtained by dividing the content in pounds 

 of each constituent by twenty, the number of hundred 

 pounds in the mixture, and the result is the number of pounds 

 of the constituent in 100 pounds of material, or the per- 

 centage composition. 



(2) Given, the materials and their analyses and the com- 

 position of the formula desired; calculate the weight of each 

 material required./^ 



Superphosphate 



Thomas slag 



Barnyard manure 

 and guaiio 



nitrate 



Lime nitrogen /"PH^H A\ ^ ~t\ J^ ^ l/\ .1^*3*) (basic calcium 

 (calcium = 



Potash salts 



Nitrate of soda 



FIG. 64. Diagram indicating what fertilizer mat rials may and may 

 not be safely mixed. The dark lines unite materials which should 

 never be mixed, the double lines those which should be applied 

 immediately after mixing, and the single lines those which may be 

 mixed at any time. 



PROBLEM: Make a fertilizer analyzing nitrogen equiva- 

 lent to 4 per cent of ammonia, 8 per cent phosphoric acid, 

 and 4 per cent water-soluble potash. Use 150 pounds of 

 nitrate of soda as a source for a part of the nitrogen and 

 derive the balance of the nitrogen from that contained in 

 ground fish scrap. The ground fish scrap contains nitro- 

 gen equivalent to 10 per cent of ammonia, and, in addition, 

 6 per cent of phosphoric acid. The potash is to be derived 



