540 The Storage of Farmyard Manure 



The important result brought out here is that no loss of nitrogen 

 occurred under completely aerobic conditions but only under the mingled 

 aerobic and anaerobic conditions obtaining when air diffuses into the 

 manure. 



The following conclusions may be drawn from the experiments 

 described in this section: 



1 . Under completely anaerobic conditions there is no loss of nitrogen, 

 the sum total of the nitrogen in its various combinations remains un- 

 changed, but there is a breaking down of complex nitrogen compounds 

 to ammonia. 



More ammonia accumulates at 26° than at 15°. 



2. Under completely aerobic conditions there is also no loss of 

 nitrogen, the sum total of nitrogen in its various combinations remaining 

 unchanged, although vigorous oxidation is proceeding. 



3. In the mixed aerobic and anaerobic conditions obtaining when 

 air diffuses into farmyard manure there is a loss of nitrogen which has 

 been traced to an evolution of nitrogen gas. The total amount of 

 decomposition is greater than under anaerobic conditions : it is possible 

 that more ammonia is formed, but if so it does not survive. 



4. The transformations of nitrogen compounds in farmyard manure 

 closely resemble those in sewage beds under both aerobic and anaerobic 

 conditions. Under anaerobic conditions they resemble also those of 

 the bacterial decompositions of protein. We suppose, therefore, that 

 the same reactions take place in all three cases. Under partial aerobic 

 conditions the resemblance ceases. It is not necessary, however, to 

 assume any change in the course of the reaction : the facts can all 

 be explained by supposing that in aU cases the complex nitrogen com- 

 pounds break down in the same way to amino-acids and ammonia. But 

 in the case of sewage and farmyard manure further reactions set in, 

 — nitrification and loss of nitrogen,^which mask the resemblance to 

 laboratory decompositions of protein. 



