PRINCIPLES OF AGRICULTURAL CHEMISTRY 



There is thus a difference of $3.00 in the price and $5.60 in the 

 valuation. Fertilizer B contains more value for the money. But 

 the purchaser must consider the needs of his crop and his soil 

 also, and not seek to secure merely the most value for the least 

 money. 



Home Mixing of Fertilizers. By home mixing of fertilizers, 

 we mean the purchase of the ingredients, and mixing them in the 

 proportions to form the fertilizer desired. The preparation of 

 acid phosphate from phosphate rock, or the grinding of bones or 



Fig- 73- Instructing negro students in the home mixing of fertilizers. 



other hard material, is most economically conducted on a large 

 scale. In home mixing, then, we simply mix the ingredients 

 which have already been prepared by grinding or otherwise. 



The operation is very simple, the apparatus required being a 

 clean floor, one or two shovels, and a sand screen, with meshes 

 of about 4 to an inch. The materials are first weighed out, one 

 by one, and piled on the floor, any large lumps being broken down 



