10 SOIL FERTILITY 



butter is due to the fact that it is made almost wholly of the 

 three elements, carbon, hydrogen and oxygen, which are so 

 common as to have no commercial value. 



Butter Made of " Wind and Water." — Chemically speak- 

 ing, butter is made of those same elements which go to form 

 water and the carbon dioxide of air. Having no fertilizing 

 value the sale of butter does not impoverish the soil. Though a 

 highly nutritious food to the consumer, it does not rob the pro- 

 ducer. This explains why it is that individual farmers, neigh- 

 borhoods, or states engaged systematically in the production of 

 butter are, in the long run, prosperous, compared with those 

 who regularly sap their soil to derive their income from the 

 sale of grain or whole milk. Butter may be said to be composed 

 of " wind, water and work." 



The value of manure has been known since antiquity. Ad- 

 monitions to fertilize and cultivate are contained in the earliest 

 writings. Manure has three values: A. Chemical, measured by 

 the amount of nitrogen, phosphoric acid and potash contained 

 in it. These are a direct food to the next crop as would be the 

 same ingredients introduced in other forms. B. Physical. 

 Manure contains fibrous materials which, rotting, yield humus 

 and loosen the soil. This open condition jjermits water to 

 enter more readily, yet to drain more promptly : also allows air 

 freer access. Aside from the purely chemical aspect manure 

 improves the soil by a change in its physical character. C. Bac- 

 terial. Countless billions of bacteria in the manure aid in its 

 decomposition, while rotting acids are liberated which dis- 

 solve portions of the soil which had, heretofore, been locked 

 securely in unavailable forms. 



Although the bacterial and physical properties are clearly 

 known to have value, they are difficult of determination. Or- 

 dinarily, therefore, the fertilizing value of manure is indicated 

 by the amount of the chemical substances carried and figured 

 only one-half as valuable as would be a like amount of the three 

 elements in a form more readily or quickly available. 



