320 Bacteria in Relation to Country Life 



and the litter, by the season of the year, and by the 

 manner of storing. 



Bacteria and conditions affecting decomposition. 

 In manure rich in soluble nitrogen compounds, certain 

 species of ammonifying bacteria appear in greater num- 

 bers, and remain active for a longer time, than in manure 

 less rich in such substances. Similarly, in the summer 

 months, the decay and putrefaction-bacteria complete 

 their work sooner and allow the appearance of the nitri- 

 fying bacteria. The daily losses of organic matter and 

 of nitrogen from cow manure are much greater in the 

 months of May, June, July, August, and September, 

 than they are in the months of February, March and 

 April. The length of the transition period is affected 

 by the amount of oxygen that gains access to the manure 

 pile. When the material is kept moist and compact, and 

 the decomposition thereby retarded, the nitrifying bac- 

 teria do not appear so soon nor are their activities so 

 prominent at the beginning. Gradually, however, the 

 structure of the manure becomes more crumbly, the 

 amount of moisture is diminished and the air finds 

 more ready access to the interior of the heap. 



AMMONIFICATION IN MANURES 



Ammonia is one of the first products formed in the 

 decomposition of protein substances. The undigested 

 nitrogenous materials in the solid excreta, as well as 

 the soluble compounds in the liquid excreta, both fur- 

 nish ammonia as they begin to undergo decay. Still 

 another source of ammonia in the manure pile may be 



