200 
Journal of Agricultural Research 
Vol. IX, No. 7 
The addition of 2 per cent of sweet com caused little or no increase in 
the ammonia content of the soils. At the end of the first 14 days all 
of the soils showed a reduction in nitrates; but during the latter part of 
the incubation period an increase in nitrates was found in all of the soils, 
with the exception of soil E, which showed a slight reduction in nitrates 
throughout the incubation period. However, the percentage of nitrogen 
recovered as nitrates was comparatively low in all cases. The only gain 
in nitrogen from the addition of sweet com was in soil U, in which the 
gain amounted to 17.39 per cent of the nitrogen added. In the other 
soils there is apparently a loss of nitrogen varying from 1.08 per cent in 
soil B to 16.31 in soil C. 
The production of ammonia and nitrates from field com was very 
similar to that secured from the addition of the same quantity of sweet 
com; but the effect on the total nitrogen content of the soil was appar¬ 
ently quite different in that all of the soils, with the exception of soil B, 
showed considerable increase in total nitrogen, the loss in soil B being 
only 1.19 per cent of the nitrogen added. 
The addition of sorghum frequently caused a reduction of the ammonia 
content of the soils, and in no case does the increase amount to more 
than 1.26 mgm. per 100 gm. of soil. The sorghum generally caused a 
reduction in the nitrate content of the soils. There is an increase in 
total nitrogen in all of the soils except C, in which the loss amounts to 
3.45 per cent of the nitrogen added. 
The addition of 2 per cent of alfalfa caused a considerable increase in 
the ammonia content of all of the soils. At the conclusion of the experi¬ 
ment from 1.65 to 4.79 per cent of the nitrogen added was recovered as 
ammonia. The nitrification of alfalfa proceeded rapidly during the first 
14 days in soil U and more slowly in the other soils. After six weeks’ 
incubation 13.7 per cent of the nitrogen added in alfalfa was recovered 
as nitrates in soil F and as much as 34.01 per cent in soil U. 
In the control samples in this series, as in the early experiment, the 
ammonia content remained fairly uniform throughout the experiment, 
but there was considerable variation in the nitrates. 
EFFECT OF TEMPERATURE AND LARGE AND SMALL APPLICATIONS OF 
DRIED BLOOD ON THE NITRIFYING POWER OF SEMIARID SOILS 
In the nitrification experiments reported above it was found that the 
soils frequently failed to nitrify dried blood when it was added in 1 per 
cent quantities. The determination of nitric nitrogen in these soils in 
the field at frequent intervals showed that the application of dried blood 
as a fertilizer invariably increased the nitrate content of the soil. It 
would seem that the difference in nitrifying power exhibited by the soils 
in the field and under laboratory conditions was probably due to the 
smaller application of dried blood under the field conditions, or possibly 
in some measure to the difference in temperature. In order to test the 
