Fixation ot Nitrogen in Colorado Soils 
CS 
of nitrates against 10.8 percent in the soil extract. It is true 
that the conditions where these samples Avere taken were pat- 
ently different though they were taken so close together; this 
is the reason that the samples were taken and our object was 
to ascertain what differences exist between the alkali, efflor- 
esced salts, and the soil extracts under the conditions obtaining 
in such places. The differences are greater and more radical 
than we expected to find them. The differences in general, but 
particularly in regard to the nitrates, are very suggestive. 
LAEGER AREA NECESSARY TO ESTABLISH GHARAGTER 
OF SOIL-EXTRAGTS 
The soils, heretofore given, are from two neighboring little 
valleys. The mixture of soluble salts is so unusual for our 
soils that it raised the question whether two or three samples 
which were taken from two places and these close together, 
represent the facts as they exist in the district. Whatever these 
facts may be it becomes incumbent upon us to ascertain and set 
them forth. For this purpose we have chosen a series of sam- 
ples representing a continuous section about 4 miles long and 
one sample 4 or 5 miles further south but in the same line. The 
choice of these samples was determined by the results obtained 
on our general samples taken in this section. 
The line of samples was interrupted because a reservoir 
and a group of small lakes intervened and the road was not 
opened. It was for this latter reason that the next sample was 
taken 6 miles further south. 
ANALYSIS OF WATER-SOLUBLE, SOIL Laboratory No. 2604 
Water-soluble equaled 9.779 percent. 
Percent 
Calcic sulfate 15.434 
Calcic chlorid 21.325 
Calcic nitrate 0.241 
Magnesic nitrate 51.159 
Potassic nitrate 4.294 
Sodic nitrate 3.809 
Ferric and Aluminic oxids 0.178 
Excess sodic oxide 3.560 
100.000 
The next sample No. 2605, was taken as a sample of alkali 
from a piece of drained land which is also affected by the nitre- 
trouble. We did not wish to obtain a sample to exhibit the 
nitre-problem but on the contrary, one to represent the alkali 
as it occurs in this section. It would have been an easy matter 
for us to have taken a sample of soil which would have shown 
only a little, perhaps no alkali. 
