500 NATUEE AND PROPERTIES OF SOILS 



produced on the farm are vital. Obviously an understanding 

 is necessary regarding tlie character and composition of farm 

 manure, its fermentative and putrefactive changes, its losses 

 in handling and storage, and above all its rational use as an 

 amendment and a fertilizer. This need appeals not only to 

 the wide-awake farmer but to the technical man as well, since 

 in the use of farm manures theory and practice widely over- 

 lap. 



282. Composition and general characteristics of farm 

 manures. — The term farm manure may be employed in ref- 

 erence to the refuse from all animals of the farm, although, 

 as a general rule, the bulk of the ordinary manure which 

 ultimately finds its way back to the land is produced by 

 cattle and horses. This arises because these animals consume 

 the greater part of the grain and roughage on the average 

 farm, and because the methods of handling such live-stock 

 make it easier and more practicable to conserve their excreta. 

 Yard manure generally refers to mixed manures. The mixing 

 usually occurs during storage, either for convenience in han- 

 dling or for the purpose of checking losses and facilitating 

 fermentation. Thus, horse and cow manures are commonly 

 mixed, since the too rapid putrefaction and consequent loss 

 of ammonia in the former is checked, while at the same time 

 a more rapid and much more complete decomposition is en- 

 couraged in the latter. 



Ordinary manure consists of two original components, 

 the solid, or dung, and the urine in about the rate of three 

 to one. As these constituents differ greatly, not only in com- 

 posifion but also in physical properties^ their proportions 

 must appreciably affect the quality of the excreta and its agri- 

 cultural value. Litter added for bedding or for absorptive 

 purposes is almost always an important factor, for while it 

 prevents losses of the soluble constituents, it may at the same 

 time lower the value of the product for a unit amount. 



While compilations of available data on the composition of 



