178 SOILS AND FERTILIZERS 



The bacterial content of the soil is greatly increased 

 by the use of farm manures, and also food is supplied 

 to the organisms already in the soil, many of which take 

 an important part in rendering plant food available. 



199. Water Necessary for Fermentation. --In order to 

 produce the best results in fermenting manure, water is 

 necessary ; for if the manure becomes too dry, abnormal 

 fermentation takes place. Water is always beneficial on 

 manure so long as leaching is prevented, for it encour- 

 ages anaerobic fermentation by excluding the air. An 

 excess of water, such as falls on manure piles from the 

 eaves of buildings, is more than is required for good 

 fermentation. During a dry time it is beneficial to water 

 the compost pile. 



200. Heat produced during Fermentation. - - During 

 active fermentation of horse and sheep manure a tem- 

 perature of 175 F. may be reached by the fermenting 

 mass. Ordinarily, however, the temperature of the 

 manure pile ranges from 110 to 130 F. The highest 

 temperature is near the surface, where fermentation is 

 most rapid. The temperature of fermentation may be 

 sufficiently high to cause spontaneous combustion, if the 

 manure is mixed with litter. 



201. Composting Manure may improve its Quality. - 



Composting manure so that leaching and rapid fermen- 

 tation do not take place may improve its quality, mak- 



