CHAPTER XI 

 BARNYARD MANTUES AND SEWAGE DISPOSAL 



Manures. One of the most important by-products of the 

 farm, as far as fertility of the soil is concerned, is the ex- 

 crement of farm animals and the litter that is used as an 

 absorbent in the stalls. Manure contains the four elements 

 necessary for the maintenance of fertility of the soil ni- 

 trogen, phosphorus, potassium, and sulphur. None of these 

 is available for the plant in the form in which it is excreted 

 by the animal, but must undergo decomposition by micro- 

 organisms. Fresh manure is harmful to plants rather 

 than helpful. The elements must pass through the cycle 

 of changes that have been previously detailed. 



The farmer desires to conserve the value of the manure as 

 far as possible, and should handle it in such a manner that 

 he may .return to the soil the maximum amount of the fer- 

 tilizing elements. Loss of the elements may occur by leach- 

 ing of the piles. This is true for all the elements. Nitro- 

 gen may be lost by being converted into volatile subs1an<-->. 

 The fanner should also remember that organic matter is 

 of value to the soil as a source of humus and to furnish 

 energy for classes of bacteria yet to be described. 



From the standpoint of the kinds of microorganisms that 

 grow in manures, this animal refuse may be divided into 

 two classes, the basis of division being the amount of water 

 it contains. Horse and sheep manure contain a smaller 

 amount of water than cow and hog manures. They are 

 also more porous and lose water more rapidly. . The solid 

 excrement of the cow dries slowly. The lack of moisture 



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