A Study ot Colorado Wheat 
19 
TOTAL NITROGEN IN SAMPLES TAKEN. 
Section 1700 
Section 1800 
Section 1900 
Total 
Total 
Total 
Depth. 
Nitrogen 
Nitrogen 
Nitrogen 
Percent 
Percent 
Percent 
0 
to 
6 
inches. 
. 0.1224 
0.1278 
0.1238 
7 
to 
12 
inches. 
. 0.1142 
0.1047 
0.0843 
13 
to 
24 
inches. 
. 0.0517 
0.0680 
0.0558 
25 
to 
36 
inches. 
. 0.0340 
0.0435 
0.0394 
37 
to 
48 
inches. 
. 0.0272 
0.0258 
0.0258 
0 
to 
6 
inches. 
. 0.1278 
0.1074 
0.1278 
7 
to 
12 
inches. 
. 0.0898 
0.0898 
0.0952 
13 
to 
24 
inches.. 
. 0.0558 
0.0585 
0.0517 
25 
to 
36 
inches. 
. 0.0354 
0.0367 
0.0367 
37 
to' 
48 
inches. 
. 0.0231 
0.0218 
0.0231 
All of the preceding samples were taken within the fallow 
strip left between the sets of four plots. 
The nitric nitrogen found in the samples taken 7 June, five 
days before the irrigation, and in those taken 24 June, ten to twelve 
days after irrigation, gives a measure of the effect of the irrigation 
upon the nitrates in the soil to the depth to which the samples were 
taken, four feet. We have six samples, each composed by uniting 
three subsamples, eighteen subsamples in all, representing six inches 
or the foot, respectively, given in the tables. We will consider only 
the surface six inches. The average amount of nitric nitrogen per 
million for this section of soil before irrigation was 8.66 p.p.m. 
On 24 June, ten or twelve days after irrigation, it was 5.18 p.p.m., 
a difference of 3.48 p.p.m. An examination of the tables also shows 
that these nitrates had been moved either into the lower portion of 
this section or still deeper. An examination of the next series of 
samples given, that for 14 July, 1913, gives a very fair idea of the 
rate at which these nitrates were being replaced, for the surface six 
inches of these same plots now contains an average of 8.8 p.p.m. a 
little higher average than was found five days before irrigation. 
The whole section of soil sampled shows the same fact, but not al¬ 
ways to so marked a degree. This accumulation of nitric nitrogen 
in the surface portions of this soil is not due to immigration of the 
nitrates from greater depths aided by capillarity. Direct experi¬ 
ment, Colorado Bulletin 186, p. 29, shows that capillary attrac¬ 
tion will not move nitrates, under ordinary atmospheric conditions, 
more than”25 inches in thirty days and their distribution through the 
soil is the reverse of that which we find in our plots. The increased 
nitric nitrogen in the soil is due to nitrification. It was shown in 
Colorado Bulletin 178, p. 86, et seq., also in Colorado Bulletin 179, 
pp. 14, 26 and 29, by W. G. Sackett, that this soil possesses such 
high fixing and nitrifying powers that these phenomena are, beyond 
question, important factors in the production of the nitric nitrogen 
found. 
