i6o 



SOILS AND FERTILIZERS 



In calculating the amount of fertility in manures, it 

 is more accurate to compute the value from the food 

 consumed and the conditions under which the manure 

 has been produced, than to use figures expressing aver- 

 age composition. 



180. Factors which influence the Composition and 

 Value of Farm Manure. - 



I. Kind and amount of absorbents used. 

 II. Kind and amount of food consumed. 



III. Age and kind of animals. 



IV. Methods employed in collecting, preserving, and 

 utilizing the manure. 



Any one of the above, as well as many minor fac- 

 tors, may influence the composition and value of farm 

 manures. 



181. Absorbents. - - The absorbent generally used is 

 straw. Wheat straw and barley straw have about the 

 same manurial value ; oat straw is more valuable than 

 either. The average composition of straw and other 

 absorbents is as follows : 



When a large amount of straw is used the percentage 

 amounts of nitrogen and phosphoric acid are decreased, 



