Phosphates in General 



the farmer should be able to judge for himself the 

 real value of the material that is offered for sale ; 

 and that, having made up his mind, he should 

 compare the net cost of the unit of the various 

 qualities of phosphates which he wishes to use. 



It is as well that phosphates are plentiful, smce 

 they are in such great demand. Arable soil is the 

 least rich in them generally, and the quantity is 

 decreasing continuall};'. The grain which is sold 

 contains proportionately to the contents of the soil 

 many more phosphates than any other agricultural 

 produce, and the cattle, which end by being sold, 

 also contain great quantities in their bones. 



This explains the necessity for using large quan- 

 tities of phosphate manures, and when applied in 

 assimilable forms too large applications can rarely 

 be given. For not only are phosphates like other 

 manures, necessary to increase the produce, but 

 also they improve its quality. And here is another 

 very important advantage that we gain : by forcing 

 fructification, they hasten maturity and so ensure 

 earlier crops. Also in regions where summer is short 

 and the ground very humiferous, where lime has to 

 be used, phosphates are absolutely necessary to 

 hasten maturity, which very often is late, and 

 sometimes never comes at all. 



In some very acid peaty soils the acidity should 

 be utilised to solubilise tricalcic phosphates, either 

 mineral or bone. 



It is necessary therefore to consider separately 

 all the substances which contain phosphates. 



It is well to remember that phosphoric acid 

 corresponds to 2*i8 of tribasic phosphate. 



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