II 
The: Fixation oe Nitrogen in Colorado Soils 
stance of the occurrence of nitre within this state which is so favor¬ 
ably located for justifying the theory of concentration from ad¬ 
joining lands as this one, and it is for this reason that I have set 
forth these facts pertaining to the composition of the alkali, the 
soils to a depth of three feet, the aqueous extracts made from these 
soils, and the solids held in solution by the ground-waters.” These 
facts were that there were no nitrates in the alkalis and none in 
the soils beyond such quantities as usually occur in soils. The 
aqueous extracts of these samples did not contain enough nitrates 
to give even a perceptible violet tinge when tested with ferrous 
sulfate and sulfuric acid in the usual way and the ground-waters 
were practically free from them. The soils yielded to water from 
24,000 to 42,000 parts per million with from 5,000 to 7,000 p. p. m. 
of chlorin. The ground-waters carried from 12,600 to 15,400 
parts of total solids per million, with from 3,100 to 4,600 parts of 
chlorin per million and only such traces of nitrates in the soils or 
the waters as it is usual to find under ordinary conditions. The 
alkali gathered from the surface of this soil carried 43.5 percent of 
sodic chlorid or 26.1 percent chlorin, but no nitrates. I stated that 
such alkalis, soils and waters could not be the source of nitrates 
found in neighboring lands even though these lands were lower and 
either the surface-water or the ground-water or both, flowed 
through and over this land. I think that this conclusion is fully 
justified. The facts in the case are that these waters do not find 
their way into the land discussed, at least, I could find no reason 
for thinking that they did then or do at the present time. The nitre 
spots presented in this connection were first observed in 1904. 
They were described as being sharply defined “brown spots on 
which nothing would grow.” They have not yet become much bet¬ 
ter though the successive owners have combated this condition by 
fertilizing heavily, by continuous cultivation and by excessive ir¬ 
rigation. The general condition of this soil is represented by the 
following facts. The surface two inches carries 44,200 parts of 
water-soluble per million, of which about 30 percent is chlorin or 
13,260 parts, and 1.6 percent is nitric nitrogen or 707.2 parts. The 
first foot of soil from the adjacent, we may say alkali field, gave 
24,500 parts water-soluble per million with approximately 4,900 
parts of chlorin and no nitric nitrogen beyond a trace. The alkali 
scraped off of the surface of this soil gave 27.6 percent soluble in 
water or 276,000 parts per million with 71,760 parts of chlorin and 
no nitric nitrogen. It is evident that the nitrates in the “brown 
spots” did not come from this source and that there is no relation 
beween any individual constituent of the alkali and the amount of 
nitric nitrogen which may be present. 
