32O PRINCIPLES OF AGRICULTURAL CHEMISTRY 



unmixed materials in large lots for cash, and make mixtures, than 

 to purchase mixed goods at retail, especially at credit prices. In 

 this way one can secure somewhat more plant food for $20.00, 

 than can be secured for $30.00, in a mixed fertilizer. The Ex- 

 periment Stations of New York, Connecticut, New Jersey, North 

 Carolina, and other States have demonstrated this to be a fact. 

 When the unmixed materials are purchased in small quantity, at 

 retail, it may or may not be profitable to make home mixtures. 

 One can easily decide this question for himself by securing prices 

 on mixed goods, and calculating the amount he would have to 

 pay for the unmixed materials to make the same mixture. 



Mixed fertilizers purchased direct from the manufacturer in 

 carload lots may often be secured more cheaply than the home 

 mixture can be made, since the cost of mixing is less to the manu- 

 facturer, who has appliances for economically handling large 

 quantities. 



It may be said further in favor of home mixtures, that one can 

 know exactly what ingredients are used, whether they are of high, 

 medium, or low grade. It is also easy to vary the mixture as de- 

 sired, and to test the effect of different combinations upon the 

 soil. 



It has been objected to home mixing that the materials may not 

 always be easily secured and that the mechanical condition is 

 not as perfect as in the commercial mixed fertilizer. Mixed fer- 

 tilizers are widely distributed and easily secured. 



Calculating the Ingredients of a Mixture. The calculation of 

 the ingredients to make a fertilizer of a desired composition, is a 

 simple mathematical matter. It is necessary, of course, to know 

 the composition of the ingredients to be used. Suppose it is 

 desired to make a fertilizer containing 8 per cent, available phos- 

 phoric acid, 2 per cent, nitrogen and 2 per cent, potash, using acid 

 phosphate containing 14 per cent, available phosphoric acid, 

 kainit containing 12 per cent, potash, and cottonseed meal con- 

 taining / per cent, nitrogen, 2 per cent, available phosphoric acid, 

 and 1.5 per cent, potash. 



