FARM MANURES 



595 



It is noticeable that nitrogen ceases to be lost under 

 anaerobic conditions, but the production of methane is 

 much increased. Carbon dioxide is present at all times. 



499. Change of bulk and composition of rotting manure. 

 — Because of the great loss of carbon dioxide during the 

 fermentation processes, there is a considerable change in 

 bulk of the manure. Fresh excrement loses 20 per cent 

 in bulk by partial rotting, 40 per cent by more thorough 

 rotting, and 60 per cent by becoming completely decom- 

 posed. This means that 1000 pounds of fresh manure 

 may be reduced to 800, 600, or 400 pounds, according 

 to the degree of change it has undergone. 



Although considerable loss of nitrogen may have oc- 

 curred through aerobic bacterial action, and although 

 both nitrogen and the minerals may have been consider- 

 ably leached away, the loss of carbon dioxide is so much 

 greater that generally there is an actual percentage in- 

 crease of the former constituents in the well-rotted prod- 

 uct. This relationship is well shown by. figures from 

 Wolff, 1 in which the samples were compared on the basis 

 of equal amounts of dry matter : — 



1 Aikman, C. M. 

 burgh and London. 



Manures and Manuring, p. 288. 

 1910. 



Edin- 



