24 
amids and monamino acids. This phase of the chemistry of bacterial 
action is in harmony, therefore, with the indications given by previous 
study on the organic nitrogen of soils. 
SUMMARY. 
(1) The ammonification of casein in silica sand was much more 
rapid during the first two days than that of dried blood, soy bean 
cake meal, cottonseed meal, or linseed meal, while soy bean cake 
meal was second in the order of decomposition. Later loss of am- 
monia by evaporation reduced the concentration of ammonia, thus 
making it impossible to compare the rates of decomposition. 
(2) During the first two days the rate of ammonification in soil 
was similar to that in sand, and a much higher percentage of the total 
nitrogen in casein was ammonified than of the other materials. On 
the ninth day 50.2 per cent of the casein nitrogen, 42.4 per cent 
in dried blood, 40.9 per cent in soy bean cake meal, 27.1 per 
cent in cottonseed meal, and 26 per cent in linseed meal had been 
ammonified. 
(3) When equal amounts of nitrogen were added, casein still under- 
went more rapid ammonification during the first two days than the 
other materials, and cottonseed meal and soy bean cake meal were 
more completely ammonified than dried blood or linseed meal. Later 
the yield of ammonia from dried blood exceeded that from cottonseed 
meal. During the nine days of the experiment 56.9 per cent of the 
nitrogen in casein, 49.3 per cent in dried blood, 48.7 per cent in soy 
bean cake meal, 32 per cent in cottonseed meal, and 34.6 per cent 
in linseed meal were ammonified. 
(4) Under anaerobic conditions all of the materials were ammoni- 
fied very slowly during the first two days. Later the casein was con- 
verted into ammonia approximately to the same extent as under 
aerobic conditions, but the other materials were decomposed much 
less vigorously. 
(5) With equal amounts of both nitrogen and nonnitrogenous 
matter present the final yields of ammonia from the different ma- 
terials, with the exception of dried blood, agreed closely, but the initial 
decomposition of casein was still much more active than the other 
substances. The yield of ammonia from casein on the ninth day was 
only 31.4 per cent as compared with 56.9 per cent in the absence of 
starch, and the ammonification of dried blood was reduced from 49.3 
per cent to 18.9 per cent. It has been suggested that the ammoni- 
fying organisms are able to utilize carbohydrates to some extent as 
sources of energy. If so, smaller amounts of ammonia would conse- 
quently be split off from proteins in the presence of carbohydrates. 
Hence the carbon-nitrogen ratio would materially affect the actual 
formation of ammonia in soils. 
