(1) By green manures and crop residues. 



(2) By accumulations in pasturing. 



(3) By applications of farm manure. 



So much has been said and written regarding the value of farm 

 manure that it is common talk that the manurial value of the food 

 is almost wholly recovered in the manure; and there is even a vague 

 notion in the minds of some that the manure is worth more for 

 soil improvement than is the food from which the manure is made; 

 while it is very generally believed that pasturing land increases the 

 fertility of the soil. 



The fact is that the most important and least appreciated method 

 of maintaining or increasing the supply of organic matter in the 

 soil is by the use of green manures and crop residues. This is best 

 understood by considering the digestibility of common food stuffs 

 and by applying mathematics to the data (see Table 29). 



TABLE 29. AVERAGE DIGESTIBILITY OF SOME COMMON FOOD STUFFS 



