CHAPTER IX 

 PURCHASE OF FERTILIZERS 



COMMERCIAL fertilizers, in the form in which they 

 are obtained by farmers, are made up of varying pro- 

 portions of one or more products from each class of 

 fertilizing materials described. That is, every manu- 

 facturer is obliged to go to these sources of supply, what- 

 ever may be the name given to the finished product or 

 mixture. Hence the fertilizing materials described are 

 not regarded as commercial fertilizers in the same light 

 as those which they are able to purchase under brand 

 names from their local dealers. In the first place, a 

 specific fertilizing material, as distinct from a manufac- 

 tured fertilizer, contains, as a rule, but one of the essen- 

 tial fertilizing elements, and its use under average condi- 

 tions would be far different from one which contains two 

 or all of the essential fertilizing elements. The materials, 

 therefore, are classed as nitrogenous, phosphatic and 

 potassic, according to whether the material contains nitro- 

 gen, phosphoric acid or potash as its chief or its only 

 constituent element; and these different classes, too, 

 may be again subdivided into two distinct groups, the 

 first including "standard," or high-grade materials, 

 and second, "general," or low-grade materials. This 

 classification is of the utmost importance. 



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