DENITRIFICATION 75 
it is not so great in less concentrated masses. In the manure heap 
there is always some loss in this way, and when great quantities 
of manure are spread over a plot of cultivated ground, denitrifica- 
tion doubtless causes considerable loss. When, however, the ma- 
nure is applied in limited quantity, so that it is mixed with a con- 
siderable amount of soil, the evidence seems to show that the losses 
are slight if any. In ordinary soil, therefore, denitrification is not 
a phenomenon of much significance. In concentrated manures, 
however, especially if they contain much hay, it may be great. 
The denitrification is greatest in fresh, concentrated manure, 
while it diminishes greatly in manure after it has partly decayed. 
Hence, the use of large amounts of partly rotted manure upon a 
soil is possible without bringing about a nitrogenous loss, while the 
use of the same amount of fresh manure would be undesirable. 
