FARM MANURE 509 



plex compounds to the most simple, is teeming with bacteria, 1 

 especially those that function in fermentation and putrefac- 

 tion. The number very often runs into billions to a gram 

 of excrement. In such an environment, it is little wonder 

 that biological changes go on rapidly. These changes may be 

 grouped for convenience of discussion under two heads — 

 aerobic and anaerobic. 



When manure is first produced, it is likely to be rather 

 loose, and if allowed to dry at once it becomes well aerated. 

 The first bacterial action is, therefore, likely to be rather 

 largely aerobic in nature. Transformations are very rapid 

 and are accompanied by considerable heat, ranging from 100° 

 to 150° F. and sometimes higher. This action falls largely 

 on the simple nitrogenous compounds, although the more 

 complicated nitrogenous and non-nitrogenous constituents are 

 by no means unaffected. Urea is particularly influenced by 

 aerobic activities and quickly disappears from well-aerated 

 manure. 



CON 2 H 4 + 2H 2 = NHJ 2 C0 3 

 NH 4 ) 2 C0 3 = NH 3 + C0 2 + H 2 



Thus nitrogen may be rapidly lost from manure by allow- 

 ing excessive aerobic decay and decomposition to proceed. 

 This loss, however, is often somewhat checked by the oxidiz- 

 ing influence of nitrifying bacteria, especially in the outer 

 portions of the manure pile. The evolution of carbon dioxide 

 which goes on continuously indicates how extensively the 

 organic matter of the manure is suffering through biological 

 activity. 



As the manure becomes compacted, especially if it is left 



moist, oxygen is gradually excluded from the heap and its 



place is taken by carbon dioxide, which is given off during 



the progress of any form of bacterial activity. The decay 



now changes from aerobic to anaerobic, it becomes slower, and 



1 Murray, T. J., Study of the Bacteria of Fresh and Decomposing 

 Manure; Va. Agr. Exp. Sta., Bui. 15, Part II, 1917. 



