12 
are aerobic, some anaerobic, while still others are able to act under 
either of the two conditions. It has also been shown at this station 1 
that ammonification actually takes place in soils during the time of 
submergence. The relative amounts of amid, basic, and nonbasic 
nitrogen occurring in soils which had long been subjected to extreme 
conditions of aeration were determined to obtain evidence as to the 
nature of the chemical changes induced by the organisms when oper- 
ating under the two sets of conditions. 
By again referring to the table (p. 9) it will be seen that the per- 
centages of the total nitrogen dissolved by hydrochloric acid were 
greater in every instance in the soils long subjected to anaerobic con- 
ditions. On an average 70.69 per cent of the total nitrogen was dis- 
solved from aerated soils, while 87.93 per cent was rendered soluble 
in the unaerated soils. These data indicate that the putrefactive 
decay, which evidently predominates in submerged soils, leaves the 
nitrogen in a form more easily dissolved by hydrochloric acid than 
the process of eremacausis, that takes place under aerated conditions. 
The relative amounts of the different groups obtained from the 
soils representing the two classes of conditions, however, were found 
to be quite similar in most instances. The table showing the nitrate 
and ammonia present (p. 7) indicates that with the exception of 
soils Nos. 347 and 406, those representing unaerated conditions con- 
tained next to no nitrate. The nitrate found in the remaining un- 
aerated soils was formed almost entirely during the time of drying 
out in the laboratory. These samples were taken from the field in 
a wet state and then contained practically no nitrate. In fact, ni- 
trification scarcely takes place at all in submerged Hawaiian soils. 
The data, therefore, fail to give any indication of a fundamental dif- 
ference in the nature of the hydrolyses which take place under aerobic 
and anaerobic conditions. 
HUMUS NITROGEN. 
The alkali soluble organic matter of soils, usually known as humus, 
is generally considered to be of special importance. Only a part of 
the organic matter present in soils occurs as humus, and generally 
very little attention is paid to the remaining. For this reason some 
study has been given to the nitrogen bodies contained in it. In this 
investigation it was hoped to learn something regarding the chemical 
make-up of these bodies by determining the amounts of the different 
nitrogen groups actually present. Some light was also sought on the 
question whether or not the alkali soluble nitrogen bodies are really 
different from the organic nitrogen of soils as a whole. The soils used 
i Hawaii Sta. Bui. 31. 
