Fixation ot Nitrogen in Colorado Soils 
19 
the emphasis laid on the snbje(*t. In fact, the question may 
seem to him to have been raised ^^atnitonsly, for this reason 
the following- analysis of a sample of surface soil taken south- 
west of Waverly and about four and a half miles west of Well- 
ington, is given and it will also serve to show the diversity met 
with in these extracts of soil samples taken within the same 
neighborhood. The locality at which this sample was taken 
was higher than the surrounding land and dark, in this case 
moist, the spot was of considerable size. Other such spots were 
observed and one other from this neighborhood was submitted 
to analysis with results similar to those presented in this case. 
ANAI.VSIS WATKR-SOLIJBLE, SOIL 1 M. W. and V 2 M. S. of Waverly, 
Larimer County^ Colorado. 
Water soluble equaled 1.96 percent of dried-soil 
Percent 
Calcic sulfate 13.264 
Calcic chlorid 52.137 
Magnesic chlorid 17.687 
Potassic chlorid 2.773 
Sodic chlorid 11.585 
Sodic nitrate • . • 1.045 
Sodic silicate 1.507 
100.000 
There are large areas in the San Luis Valley where these 
chlorids, especially calcic chlorid, occur abundantly. The most 
striking examples of this that I have met with are in a district 
southwest of Alamosa. The two districts are not to be con- 
founded for they are unlike in every other respect. 
The prevalence of magnesic salts in these soil extracts sug- 
gests a question regarding their source, i.e., whether there is 
any unusual amount of them present in the soil itself and not 
soluble in water. To answer this a soil that had been washed 
free from chlorids and sulfates was submitted to an ordinary 
agricultural analysis. The results showed nothing unusual- 
The carbon dioxid, lime and magnesia were low for our soils. 
The lime OaO was 1.42 percent and the magnesia 0.336 percent. 
The alkalis were also relatively low, potassic oxid 0.654 and 
sodic oxid 0.103 percent. 
The origin of this soil is principally the friable sandstone 
lying above the shale. There is undoubtedly an admixture from 
other sources but the local rocks are the principal source. 
CERTAIN WELL-WATERS 
We have previously stated that our attention was first 
seriously directed to the conditions in this section by the oc- 
currence of nitrates in certain well-waters. This proved to be 
