The: Fixation of Nitrogen in Colorado Soils 25 
Sanitary Analyses in Parts per Million. 
Total solids . 9,788.000 18,557.000 13,258.000 
Free ammonia . 0.170 0.310 
Alb. ammonia . 0.128 0.525 
Nitrous nitrogen . Trace Not determined 
Nitric nitrogen . 4.000 318.800 441.500 
Chlorin . 760.000 1,390.300 1,567.000 
We have given the results of the examination of thirty-six 
samples of ground-water which show from no nitric nitrogen up 
to 441 parts per million. In several cases we find very small 
amounts in the surface-soil at the time the samples were taken and 
find that this increased as we gained depth till we encountered the 
ground-water which was richer in nitrates than any section of the 
soil. There can scarcely be any doubt but that this was due to the 
washing of the nitrates down into the soil, which is the direction 
in which the nitrates are usually found to move. In one case we 
found that the ground-water before irrigation carried only traces 
of nitric nitrogen, but after a copious irrigation, whereby the 
ground-water was raised to within a few inches of the surface, we 
found 106 parts per million. The evident explanation of this is that 
the nitrates were dissolved out of the surface-soil and transferred 
to the ground-water. Three months later when this irrigating 
water had drained out of the soil, the nitric nitrogen had fallen to 
less than one-tenth-part per million. I have already stated that 
the total solids in these ground-waters decreased as the water-plane 
fell, this was the case in these samples. In July, immediately after 
irrigation when the water-plane was near to the surface, the total 
solids carried by the water amounted to 7,862 p. p. m. and the nitric 
nitrogen to 106 p. p. m. In October, when the water-plane had 
fallen, the total solids amounted-to 1,201 p. p. m. and the nitric 
nitrogen to 0.04 p. p. m. This water carried, in July just before the 
ground was irrigated, only a trace of nitric nitrogen. We have 
here clear proof that the nitric nitrogen was not deposited by the 
evaporation of ground-water and was not brought into this area 
from adjoining land by ground-waters. 
We have in another case, not referred to in the previous para¬ 
graphs, a demonstration of the same facts, i. e. that the nitrates do 
not come from below and are not deposited on the surface by evap¬ 
oration of the water. In this case the land was in bad condition, 
the details of which we will not give. I made persistent inquiry 
regarding the underground-water conditions and dug a hole to a 
depth of about four feet, but could not find that the water-plane 
was very near the surface. The property changed owners and the 
new owner started to investigate these conditions by having holes 
dug in order to ascertain the depth of the water-plane. He ob- 
