i8 
Colorado Experiment Station. 
by the amount of moisture in the manure. The probability is that the 
conditions were right in some manures for the work of nitrifying 
bacteria. In other manures the nitrates had been washed away or 
nitrification had not taken place. 
The three highest results, viz., Nos. 26, 27, and 33, have 27.13, 
14.13 and 25.94 percent, respectively, of their nitrogen present as 
nitrates, which will be seen to be abnormally high as compared with 
Holdefeiss’ figures. 
The question might be raised whether nitrification had, not pro¬ 
ceeded in the sample cans in the laboratory. This was effectually set¬ 
tled in the case of No. 17. A determination of the nitrates in the 
three-year-old sample had been made in 1906 and a re-determination 
of nitrates in 1910 gave practically the same result. Air-drying the 
manure seems to stop most bacterial changes. 
THE FREE AMMONIA. 
The free ammonia in the manures which have been discussed 
in the foregoing pages offers a very interesting study not only because 
of the larger amount in fresh manures, but because it is the most easily 
lost of all the elements of fertility under our conditions. It has been 
pointed out that the principal loss from manures under humid condi¬ 
tions is potash but that the greatest loss in our climate is nitrogen. 
From the following discussion it will be seen that this loss occurs princi¬ 
pally through a loss of free ammonia. 
The bacterial changes taking place in the manure heap are very 
complex and not fully understood, but it is certain that among the first 
of these changes is the ammoniacal fermentation which first changes 
the nitrogen compounds of the liquid manure into ammonium salts, 
or allows the ammonia to escape into the air. Some of the am¬ 
monium salts are now oxidized to nitrites but are not changed into 
nitrates until all the ammonia has been dissipated or has combined to 
form neutral salts. The process is quickly completed in the liquid 
manure which contains organic nitrogen in a soluble form. The nitro¬ 
gen in the solid portion is also attacked by ammonifying bacteria, but 
this change takes place slowly, which allows more time for the change 
into nitrates and nitrites. The great loss of ammonia from our sheep 
manures, however, must come from the comparatively swift change 
of large amounts of hippuric acid from the liquid manure into ammo¬ 
nia through the agency of uro-bacteria. 
We know that most of this ammonia immediately combines to 
form ammonium carbonate, and being in this form it is peculiarly sus¬ 
ceptible to changes in temperature and to the presence or absence of 
moisture. Now ammoniacal fermentation takes place most readily 
when the bacteria have a plentiful supply of air, warm sunshiny weath- 
