8o 
Journal of Agricultural Research 
Vo!. VII, No. a 
Attention must be called to the fact that the classification for purposes 
of discussion of the Pasadena area as a coast valley is not done with any 
idea of so classifying it permanently. It is merely done to emphasize 
its closeness to the sea and its greater rainfall and attendant factors 
which affect many of the soils in that area so as to make them more 
characteristic of coast than of interior valley conditions under which 
the Pasadena area would normally be classed.. 
Several other minor points of interest with respect to the data which 
have been discussed deserve consideration here. Most of the soils above 
studied from the South Atlantic States are deficient in nitrogen, and in 
that respect resemble, for example, the truly arid soils of the Riverside 
area. Likewise, with respect to the nitrification of nitrogen in dried 
blood and cottonseed meal, but particularly the former, the South 
Atlantic soils behave more like the truly arid soils. Their behavior 
could therefore be accounted for on the hypothesis explaining the 
behavior of the truly arid soils toward dried-blood nitrogen, taking the 
low nitrogen content of the soils as an index of the organic matter present 
and, hence, indirectly of the total internal surface. That, however, 
aside from the total nitrogen considerations and their indications that 
climate exerts additional effects on the soil's nitrifying power, is exem¬ 
plified by the fact. that the South Atlantic soils, while behaving 
toward dried blood and partly toward cottonseed meal like arid soils, 
stand, with respect to soil nitrogen and sulphate of ammonia, in the 
position of the truly humid soils. The latter is more easily explicable 
on the basis of soil acidity with respect to sulphate of ammonia and that 
of superior moisture conditions with respect to the soil nitrogen. It 
will be noted that two soils which did not nitrify their own nitrogen well 
are the Kentucky and Louisiana soils. The first was collected in De¬ 
cember and the second in March, which would probably account for the 
relative inactivity of the nitrifying organisms. With the exception of 
the last two soils, it will be noted in Table I, Group I, that the South 
Atlantic soils are far superior in their nitrifying powers for soil nitrogen 
to the soils of the Riverside area. 
It will be noted that the total nitrogen content of soils in connection 
especially with the nitrification of dried-blood nitrogen has several times 
been emphasized. This is done to indicate, in a general way, the likeli¬ 
hood of the presence of certain quantities of organic colloids in the soil 
on the assumption that the soil's nitrogen content bears a more or less 
intimate relation to the quantity of organic matter present. The latter, 
moreover, is considered as an indication in its turn of the amount of 
internal surface contributed to the soil from that source in addition to 
that present there by virtue of the surfaces of inorganic constituents, 
including sand, silt, and clay. 
