58 



HATCH EXPERIMENT STATION. 



[Jan. 



How to use the table of trade values in calculating the ap- 

 proximate value of a fertilizer : Calculate the value of each 

 of the three essential articles of plant food (nitrogen, phos- 

 phoric acid and potassium oxide, including the different 

 forms of each wherever different forms are recognized in the 

 table) in one hundred ])ounds of the fertilizer, and multiply 

 each product by twenty, to raise it to a ton basis. The sum 

 of these values will give the total value of the fertilizer per 

 ton at the })rincipal places of distribution. An example will 

 suffice to show how this calculation is made : — 



Analysis of Fertilizer (Per Cent., or Pounds in One Hundred 

 Pounds of Fertilizer) . 



Nitrogen, 4 



Soluble phosphoric acid, .8 



Reverted phosphoric acid, 4 



Insoluble phosplioric acid, 2 



Potassium oxide (as sulfate), 10 



The following table gives the average analysis of officially 

 collected fertilizers for 1900 : — 



