Organic Matter (Humus) 42 



Peas, Green Manure 41 



Phosphate Guanas 14 



Phosphoric Acid, Cheapest Form 14 



Phosphoric Acid, Cost of. 22 



Potash, Effect of.... 35 



Phosphoric Acid, Effect of 34 



Phosphoric Acid, Sources of. 11 



Plant Food, Definition 6 



Potash, Cost of. 23 



Potash, Sources of. 15 



Purchasing, General Principles 24 



Purchase of Fertilizers 18 



"Simples" 27 



Soil Analysis, Value of. 47 



Source of Fertilizers 8 



Stable Manure 39 



Steamed Bone 12 



Thomas Phosphate Slag 13 



Unnecessary Fertilizers, Avoiding Purchase 36 



Use of Fertilizers 33 



EXPLANATORY NOTE. 



The statement made in the paragraph near the top of 

 page 12, that the insoluble form of phosphoric acid has 

 "no commercial value" should be modified. State agri- 

 cultural stations usually attribute some commercial value 

 to this form of phosphoric acid, say about 2 cents per 

 pound, while the water soluble form would be regarded as 

 worth considerably more. The agricultural value of 

 insoluble, or tri-basic, phosphoric acid is very much greater 

 than the commercial value or the station value. (See also 

 "Cheapest Form of Phosphoric Acid," page 14, and 

 "Commercial vs. Agricult-ttral*4Jalue," page 32.) 

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