FARM MANURES 



177 



manure is very small. Under poor conditions losses by 

 fermentation may exceed 15 per cent. Hen manure, 

 sheep manure, and horse manure are the most ferment- 

 able, particularly when fungous growths and molds are 

 formed. When extreme conditions, as excessive mois- 

 ture, are followed by drought and high temperature, 

 then the greatest losses occur. 



198. Different Kinds of Fermentation. -- The large 

 number of organisms present in manure all belong to 

 one of two classes: (i) aerobic, or (2) anaerobic. The 

 aerobic ferments require an abundant supply of air in 

 order to carry on their 

 work. When deprived 

 of oxygen, they become 

 inactive. The anaero- 

 bic ferments require 

 the opposite condition. 

 They become inactive 

 in the presence of oxy- 

 gen and Can thrive Only FlG " 3 6 - Fermentation of Manure. 



when air is excluded. In the center of a well-constructed 

 manure pile anaerobic fermentation occurs, while on 

 the surface aerobic fermentation is active. The anaer- 

 obic ferments prepare the way for the action of the 

 aerobic. When aerobic fermentation is completed, the 

 organic matter is converted into water, carbon dioxide, 

 ammonia, and allied gases, and these are lost. Conse- 

 quently, anaerobic fermentation is the most desirable. 



