CHAPTER XXVIII 



THE BACTERIA IN MANURE— AMMONIFICATION 



Animal excreta are extremely rich in microorganisms. 

 Most of these organisms are typical inhabitants of the 

 intestinal tract. The others are derived from the food 

 eaten by the animals and are not apparently destroyed 

 by passing through the animal system. Among the 

 latter should be included certain spore-forming bacteria 

 which occur in large numbers on substances of vegetable 

 origin. For example, Wuthrich and Freudenreich found 

 in hay 7,500,000 bacteria per gram of substance. Twenty 

 five per cent of these belonged to the spore-bearing 

 Bacillus subtilis (hay bacillus) group. In sour potatoes, 

 on the other hand, with about 5,000,000 bacteria per 

 gram, the proportion of hay bacilli was comparatively 

 slight. When fed to animals, the bacterial content of 

 these materials apparently affected that in the manure. 

 It was noted, for instance, that the manure of animals 

 fed on grass contained 1,800,000 to 12,250,000 bacteria 

 per gram, consisting largely of the colon bacillus and the 

 hay bacillus. When the animals were fed on hay, the 

 manure contained 20,674,000 to 375,000,000 bacteria, 

 also consisting, for the most part, of the two organisms 

 just named. 



Changes in manure bacteria.— In his examinations of 

 (318) 



