The Fixation of Nitrogen in Colorado Soils 13 
actually present, which quantities, in this case are 5,926 parts of 
nitrates to 1,053 parts of chlorids, or in the ratio of 1 : 0 . 17 , or 
stated differently, 0.6 per cent of the dry soil is composed of sodic 
nitrate and 0.1 percent of sodic chlorid. 
We have now presented the details of two very distinct 
localities in which we find some lands seeped and strongly alkalized 
and in which also occur “brown spots on which nothing will grow,” 
nitre-spots. These have been given to show that the nitre found 
in the “brown spots” does not owe its origin to the alkalis nor to 
the concentration of the ground-waters. We will briefly restate 
our results to show that there is no relation whatsoever between 
the alkalis and these nitre-spots which in any way justifies the view 
that the “brown spots” owe their origin to seepage, or have a com¬ 
mon origin with the alkalis. 
In the first case cited the alakalis were gathered and analyzed 
and while they always carried chlorin, some of them as much as 
five percent of their weight, none of them carried more than heavy 
traces of nitric nitrogen, and some of them carried none at all. 
The soil samples taken from four different parts of this piece 
of land showed no unusual amounts of nitrates. These samples 
represent the first and second two inch sections of the soil and gave 
the following results in parts per million: 
FIRST TWO 
INCHES. 
SECOND TWO 
INCHES. 
Water-Sol. 
Chlorin 
Nitric 
Nitrogen 
N :C1. 
Water-Sol. 
Chlorin 
Nitric 
Nitrogen 
N :C1. 
39,314.0 
2,145.0 
7.1 
1:302.0 
25,500.0 
229.0 
Tr. 
Tr :229.0 
7,500.0 
300.0 
36.0 
1: 8.3 
3,890.0 
112.0 
0.3 
1:130.0 
20,544.0 
881.5 
12.3 
1: 72.0 
8,130.0 
218.0 
1.6 
1:147.0 
8,000.0 
216.0 
19.2 
1: 11.0 
8,640.0 
54.0 
2.1 
1: 27.0 
These samples were taken at the same time and show that in 
some sections of the land the alkali was very abundant but that there 
was no relation between the amount of alkali in the soil and the 
amount of nitric nitrogen present. Further they show that there 
is no relation between the chlorin in the soil and the nitric nitrogen. 
We find this true in both of the two-inch sections taken. The 
nitric nitrogen found in this strongly alkaline soil is by no means 
remarkably high unless the figure 36.0 p. p. m. nitric nitrogen be 
considered higher than usual which, I think, would in general be 
justified, but not in Colorado, for we often find much higher fig¬ 
ures than these for ordinary, cultivated soils. 
We also examined the ground-waters from this area and found 
them to contain total solids varying in quantity from 1,600 to 
10,357 P- P- m -, chlorin from 68 to 971.0 p. p. m., and nitric nitro¬ 
gen from a trace to 106.0 p. p. m. There is no relation between 
the amounts of nitric nitrogen and those of chlorin. We have with 
