CROPS AND SOIL IMPROVEMENT 



of soda should not be the sole source of nitrogen in 

 a fertilizer on account of its immediate availability. 

 Manufacturers use some sulphate of ammonia, 

 and a pound of nitrogen in it has had practically 

 the same market price as that in nitrate of soda. 

 Tankage may be used in part, and in it the nitro- 

 gen costs very little more per pound. 



It may be said that the potash in the fertilizer 

 is in form of sulphate. Usually that profits the 

 user nothing, and often the claim is baseless, but 

 if it is a sulphate, the cost of the potash should 

 have only 20 per cent added to the valuation of 

 the potash, which usually will not add one dollar 

 to the total cost of the ton of mixed fertilizer. 

 Basing the valuations of the pounds of plant-food 

 in the mixed fertilizer on the value per pound in 

 unmixed materials delivered to one's own locality, 

 there must be taken into account the added ex- 

 pense of mixing. 



High-grade Fertilizers. A high-grade fertilizer 

 is not necessarily a high-priced one. What we 

 want in a fertilizer is a high content of the plant- 

 food needed, together with desirable availability. 

 If only phosphoric acid is wanted, a 14 per cent, 

 or 16 per cent, acid phosphate is high-grade 

 because it contains as many pounds of available 



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