CROPS AND SOIL IMPROVEMENT 



which varies little from 20 per cent of nitro- 

 gen, or 20 pounds in the 100, he will get his 9 

 pounds of nitrogen for an acre by buying ^ 

 of 100 pounds, or 45 pounds, and the substitution 

 of the 45 pounds of sulphate of ammonia for 

 the 60 pounds of nitrate of soda will reduce 

 the total application of fertilizer per acre from 

 310 pounds to 295 pounds. The imporant fact 

 is that in either case there is the required amount 

 of nitrogen. 



Let us assume that the field contains enough 

 nitrogen, but other needs remain the same. In 

 such case, the nitrogen is dropped out, and the 

 application becomes 250 pounds per acre. 



The home-mixer may substitute tankage of 

 guaranteed analysis for part of the nitrogen and 

 phosphoric acid. Let us assume that the tankage 

 runs 9 per cent nitrogen and 20 per cent phos- 

 phoric acid. If half the required nitrogen per 

 acre, or 4J pounds, is wanted in tankage, 50 

 pounds of the tankage will supply it. At the same 

 time the 50 pounds of tankage supplies 10 pounds 

 of phosphoric acid, replacing one third of the 214 

 pounds of acid phosphate. We thus have for 

 the acre 30 pounds of nitrate of soda, 50 pounds 

 of tankage, 143 pounds of acid phosphate, and 36 



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