THE FERMENTATIONS OF MANURE 79 
Such portions of it as unite with carbon dioxid to form ammonium 
carbonate are less volatile, but this, too, is partly volatilized. The 
odor of ammonia common around a manure heap plainly demon- 
strates thisloss. (2) Denztrification If by this term we refer only 
to the reduction of nitrates so as to set nitrogen free, the process is 
not very important in a manure heap, since there is present only a 
little nitrate, none, indeed, at first, when the fermentations are 
greatest. If nitrates are present, denitrification will cause a loss, 
and in the later stages of the rotting of manure, after nitrates are 
formed, this loss might be considerable. But it seems that loss 
from this cause is not so great as was formerly supposed. (3) 
Desiruciton of ammonta. ‘There seems to be a direct “‘burning” 
of ammonia compounds in the manure heap by which the nitrogen 
is set free from it as free nitrogen. Little is known concerning this 
factor at present. 
The extent of the nitrogen losses from these sources may be 
considerable. Various estimates of the amount have been made, 
and it seems not beyond the mark to say that, under poor manage- 
ment, at least 50 per cent. of the nitrogen is lost to the manure, and 
sometimes considerably more than this. When the farmer re- 
members the high cost of nitrogen fertilizers he may perhaps real- 
ize the very poor economy of allowing this loss to continue. Not 
all the loss is avoidable, for under the best conditions, perhaps 
15 per cent. is lost, but even if this is true, 35 per cent. may be 
saved by proper care. Itis possible for a farmer to know when this 
loss is becoming excessive by two means: (1) The appearance of 
a strong odor of ammonia tells its own story; and while some such 
odor may always be expected, a strong odor indicates a toorapid 
loss. (2) The heating of the manure indicates rapid aerobic fer- 
mentations and this is always accompanied by a large nitrogen 
loss. Properly kept manure will not show a great rise in tempera- 
ture and never a rapid one. The farmer may be confident that a 
noticeable heating of his manure pile means a large loss. Some 
manure heats more rapidly than others, that from the horse being 
