34 The Colorado Experiment Station 
six years during which we have had this land under observation, 
have found excessive quantities of nitrates. This has not been the 
case and is not now the case. I have in previous publications 
stated that land may be so wet as to preclude the occurrence of 
nitrates, at least such occurences as we have made the subjects of 
our study. This statement does not apply to the greater part of 
this land, if it does to any of it. A portion, that is spots here and 
there in this land, is certainly in bad condiion at the present time. 
This is not due to nitrates but to water. Within half a mile of this 
land, however, occur some bad ‘and persistent nitre-spots where 
there is no excess of water or alkali. Alkalied land and nitre- 
spots are not synonomous terms, a fact which I have frequently 
stated. One might think that the surface portion of this soil is the 
portion richest in soluble salts; this is not the case, at least not 
necessarily so, for we have found the soil at a depth of two and 
three feet, richer in soluble matter than the first foot, but so good 
as free from nitrates. In this land we have a very great concentra¬ 
tion of the chlorids in the surface-soil without nitrates, showing that 
this concentration may be entirely independent of the nitrates. In 
other cases, we have the nitric nitrogen present in excess of the 
chlorin. Large amounts of chlorin occur generally with excessive 
nitrates. This seems accidental and not necessary. 
The third place selected was land in a portion of which the 
nitrates had quite recently developed in very deleterious quantities. 
In 1909 there was some burning, in 1910 a few trees died, in 1911 
a portion of the orchard was destroyed. I counted at one time 
thirty-five successive trees in a row that had died within two weeks. 
These were not small, weak trees, but well grown, and previous to 
this time, healthy appearing trees. “Brown spots” were very 
marked in portions of this third piece of land selected; in others 
there was nothing noticeable, but in the greater portion, the whole 
surface showed by its general color the presence and activity of the 
Azotobacter. This section of the land, particularly in 1911, was 
puffed up and oily looking. I do not recall having at any time seen 
an incrustation of alkali on it. This may have been due to the 
careful cultivation that it received. I think that this is probable, 
for adjoining land, similarly located and separated from this by 
a wire fence, did show such incrustation where it was not occupied 
by a good stand of alfalfa. We took a large number of samples 
from this third place, representing the alkali ground in the alfalfa 
field, the surface soil of one acre of the orchard land to a depth of 
seven inches, the top three inches being taken as one sample and the 
succeeding four inches being taken as a second sample. We also 
made in all nineteen sections of this acre of land, digging in each 
