CHAPTER XVI 

 MIXING OF FERTILIZERS 



112. Advantages of Home-Mixing. Phosphorus, ni- 

 trogen and potassium are the three elements most usually 

 found necessary to be supplied to a soil to keep up its 

 fertility. The sources of these elements have been dis- 

 cussed. The next consideration is how to apply most eco- 

 nomically these purchased plant foods. 



Fertilizer factories are equipped with machinery that will 

 mix thoroughly the raw materials, provided their work is well 

 done. That this work is not always thoroughly done and 

 that the materials are not always compounded so as to ap- 

 proximate the desired mixture, is readily seen by examining 

 any of the many Fertilizer Control Reports issued from the 

 various Experimental Stations. When fertilizing materials 

 are mixed, it is extremely difficult to determine with any 

 degree of exactness the kind and proportion of all of the 

 raw materials used. Due to this fact, a small amount of 

 cheap and unavailable plant food, especially low-priced 

 nitrogen, can be, and often is, worked into the mixture. The 

 fertilizer manufacturers charge for mixing from $3 to $7 per 

 ton. There are a number of formulas that farmers have 

 become accustomed to buy of which some are very low grade. 

 In mixing such formulas, the manufacturer must necessarily 

 add some " make- weight " to his high-grade materials to 

 bring the mixture to the desired percentage. This " make- 

 weight " is known as the filler. 



The transportation and hauling of filler is a heavy and 

 unnecessary expense that can be avoided by the purchase 

 and home-mixing of high-grade materials. The greatest 

 advantage to be gained by the home-mixing of commercial 



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