262 FARM MANURE 



In the solid excrement nitrogen is present in protein 

 forms which have resisted decomposition in the digestive 

 tract of the animal, and hence do not decompose very rapidly 

 in manure. In the litter the nitrogenous compounds are also 

 proteins, and although somewhat more easily broken down 

 than the proteins of the solid excrement, they are not decom- 

 posed very rapidly. Considering the nitrogen compounds in 

 the solid part of the manure, it can be said that they break 

 down in the presence of air with the formation of ammonia 

 which escapes into the atmosphere. Moreover, in the 

 presence of plenty of air, ammonia is further oxidized to 

 free nitrogen. True nitrification, that is, the formation of 

 nitrates, is not a common bacterial change in manure piles. 



Aerobic decomposition results in a gradual change of 

 carbohydrates — cellulose, starch, and pentosans — and of fats, 

 as well as of proteins, to carbon dioxide and water, with 

 the intermediate production of organic acids. Compounds 

 containing potassium and other bases decompose with the 

 formation of carbonates of the bases. Phosphorus and 

 sulphur in proteins remain as phosphates and sulphates, 

 or more correctly speaking as phosphoric and sulphuric 

 acids which are neutralized by the bases present. As a 

 matter of fact, there is an excess of alkaline carbonates in 

 decomposing manure piles, whether the action is aerobic 

 or anaerobic. This is evidenced by the dark liquids which 

 may be seen draining from manure piles. This dark liquid 

 is an alkaline extract of humus, for humus, or at least humus- 

 like compounds, result from partial decomposition of the 

 organic matter, more particularly where there is not much 

 air present. 



In general, aerobic decomposition of manure results in the 

 production of considerable heat. Horse and sheep manure 

 being more porous and drier, decompose very easily and 

 are called "hot" manures. The manure of pigs and cattle, 

 on the other hand, are more compact, contain more water, 

 and hence do not decompose so rapidly. They are called 

 "cold" manures. The loss of carbon dioxide and water from 

 manure, of course, results in loss of weight. 



