312 Bacteria in Relation to Country Life 



concluded that an estimated loss of 50 per cent of the 

 total nitrogen contained in the foods is not too high 

 for manure made under average conditions of farming." 



The losses of nitrogen that occur in decomposing 

 manure, fall most heavily on the soluble portion. Wag- 

 ner calculates that to every 100 parts of insoluble or 

 inactive nitrogen there should be voided by the animals 

 100 parts of soluble or active nitrogen. As a matter of 

 fact, however, we find only 25 to 35 parts of the latter 

 to 100 parts of the former in fresh manure. The discrep- 

 ancy is evidently due to the greater susceptibility of 

 the soluble nitrogen compounds to attacks by bacteria. 



On the other hand, the solid excreta and litter suffer 

 comparatively little from the destructive bacterial 

 changes. This fact has suggested the separate collec- 

 tion and preservation of the liquid and solid excreta. 

 It is claimed that the inert nitrogen compounds in the 

 latter will resist decomposition more effectively in the 

 absence of the former. The liquid excreta drained into 

 a cemented pit will be but little accessible to aerobic 

 bacteria on account of the anaerobic conditions in the 

 interior of the liquid. 



Aerobic and anaerobic decomposition. — The smaller 

 losses of nitrogen in compacted manure, as compared 

 with those in loosely stored manure, are readily accounted 

 for by "the different conditions as to bacterial develop- 

 ment prevailing in one and in the other. As previously 

 noted, aerobic processes prevail in the loosely stored 

 manure or in its upper layers, and the organic matter, 

 containing nitrogen, undergoes a correspondingly rapid 

 decomposition. The carbon and the hydrogen find an 



