11 
at the same time somewhat difficult to separate entirely from the 
nonbasic nitrogen in the solution. For these reasons some variation 
in the results is to be expected. 
NONBASIC NITROGEN. 
The percentages of nonbasic nitrogen, with the exception of that 
from soil No. 447. were found to be remarkably similar in every in- 
stance, amounting to about two-thirds of the nitrogen dissolved by 
boiling hydrochloric acid. In this respect the soluble nitrogen of soils 
is quite similar to that of vegetable proteins. The nonbasic nitrogen 
of soils is looked upon as being composed largely, but not entirely, of 
monamino acids, and probably such as are obtained in the hydrolysis 
of protein. Robinson, 1 for example, isolated leucin and isoleucin 
from hydrochloric-acid solutions of Michigan peat. Doubtless* other 
monamino acids occur in the solutions. It is claimed, however, that 
a considerable portion of the nonbasic nitrogen of soils occurs in forms 
other than as monamino acids. Robinson, by the use of the Van Slyke 
nitrous acid method for the determination of monamino acids, found 
considerably less monamino acid in solution than was necessary to ac- 
count for the nonbasic group, while Jodidi arrived at similar conclusions 
by the use of the formaldehyde titration method. Osborne, 2 has pre- 
sented data supporting the idea that the nonbasic nitrogen obtained 
from vegetable proteins actually occurred as monamino acids. As 
yet no explanation of this difference between the nitrogen of soils 
and that of vegetable proteins has been proposed. The soluble non- 
basic nitrogen in Hawaiian soils approximates the amounts found in 
soils elsewhere. 
EFFECTS OF AERATION ON SOIL NITROGEN. 
Some references have already been made to the fact that a wide 
range in the degree of aeration prevails in different Hawaiian soils, 
and that some of the soils studied in this investigation represent ex- 
tremes in this respect. By reference to the previous description of 
the soils it is seen that soils Nos. 379, 428, and 447 represent aerated 
soils, 379 and 447 particularly so, since they are taken from well 
aerated land in sections where semiarid conditions have prevailed 
for many years. The remaining soils studied represent anaerobic con- 
ditions, since they have been used in aquatic agriculture a large part 
of the time for many years. So far as known no nitrogenous fer- 
tilizers of any sort have been applied to any of these soils. 
It is generally held that the production of ammonia from organic 
nitrogen is necessary before its nitrification can takeplace, and that am- 
monia can be formed by a wide range of soil organisms. Some of these 
i Loc. cit. 2 The Vegetable Proteins. London and New York, 1909. 
