CHAPTER XXIX 

 DENITRIFICATION IN MANURES 



REFERENCE is occasionally made to losses of nitro- 

 gen from the manure pile as due to denitrification. In 

 the proper definition of the term, namely, the destruc- 

 tion of nitrates with the evolution of gaseous nitrogen, 

 denitrification processes in manure are by no means as 

 extensive as is commonly supposed. 



Nitrates in manure. No nitrates are present in fresh 

 manure, since the large quantities of soluble organic 

 matter are unfavorable to the development of the nitri- 

 fying bacteria. Subsequently, however, when changes 

 more or less deep-seated had occurred in the organic 

 matter, the nitrifying bacteria make their appearance 

 in the upper layers of the manure pile where the supply 

 of air is more abundant. 



The nitrates thus formed may be diffused downward 

 or washed down by rain and reduced to nitrogen gas. 

 It is doubtful, however, whether, under actual condi- 

 tions, the reduction of nitrates in the interior of the 

 manure pile is as far reaching as that. More frequently, 

 the reduction is only partial and no escape of nitrogen 

 gas occurs as a result of denitrification. Losses of ele- 

 mentary nitrogen do occur in the manure pile, but are 

 brought about by different bacterial processes. 



(326) 



