CHAPTER II 



SOIL FERTILITY 



As the dairy industry is so closely related to the maintenance 

 of soil fertility, the dairy farmer is bound to consider this as no 

 small element for consideration in the profits from the dairy. 



SOIL FERTILITY 



Fertilizing Value of Plant and Animal Products. — As is 

 well known, every plant which grows from the ground absorbs 

 and approjiriates to it>^olf portions of the soil in which it gTew. 

 The quantity and the proportions of the ingredients vaiy con- 

 siderably with the nature of the plants. Of the eighty odd 

 chemical elements known, only ten to eleven seem to be abso- 

 lutely essential to plant life. Of these only three are present 

 in such small amounts, and used in such large amounts as to 

 create a keen necessity that their presence be assured. These 

 three are: nitrogen (measured as nitrogen, jST), phosphorus 

 (measured as phosphoric acid, P2OB), and potassium (measured 

 as potash, KoO). Many soils axe so lacking in one or more of 

 these essential substances that they must be provided in some 

 artificial way. This condition has brought into existence firms 

 dealing in commercial fertilizers. Immense quantities are regu- 

 larly sold in this country, especially in the eastern and southern 

 states. The three constituents thus marketed are nitrogen, 

 phosphoric acid and potash, in varying forms and with varying 

 values. Since farm crops all contain more or less of these sub- 

 stances they have a fertilizing value usually measured by their 

 composition and the market price of these three essential con- 

 stituents. Prices are slowly increasing. Eeadily available 

 nitrogen is now worth about 20 cents a pound ; phosphoric acid 

 and potash each about 5 cents a pound. Below is given a table 

 showing the amount of these three elements contained in 1000 

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