22 
Colorado Experiment Station. 
that this part of the young orchard would be the first to go. As fast 
as the trees died they were taken up and in 1910 at least twelve acres 
were sown to corn. Only a very small per cent of this ever reached a 
height of eighteen inches, and* much of it never came through the 
ground. All over the area involved there are great barren spots, 
some of them a half acre in extent, where not even a Russian thistle 
will grow. A two inch surface sample was taken from one of these 
spots, October 29, 1910, and contrary to expectation my culture de¬ 
veloped a yellowish surface membrane with brown patches. Azotobac- 
ter was very plentiful. After thirty days the culture showed an in¬ 
crease of 8.6862 m. g. of nitrogen. Inasmuch as all vegetation had 
refused to grow where the sample was collected, I had rather imagin¬ 
ed that the Azotobacter would be killed out as well, and was not 
anticipating any such active fixation as was secured. 
Samples Nos. 29, 30 and 31. 
The next orchard presents, without exception, the most severe 
case of nitre that has been called to our attention; severe not only in 
point of destruction, but in rapidity of spread as well. We have seen 
orchards where the isolated trees and parts of rows were scattered 
over a large area, but nowhere else have we observed one solid row after 
another, the entire length of the orchard, go down in rapid succession, as 
clean as before a forest fire. The original orchard covered about 15 acres 
of ground sloping gently to the south and, as measured by its produc¬ 
ing capacity, was in excellent condition up to the winter of 1909-1910. 
At this time a spot about twelve feet in diameter appeared at the lower 
edge of the tract, which the manager stated always looked wet and 
black in color. Little attention was paid to this until the spring of 
1910 when the trees in this vicinity began dying as with nitre. The 
trouble spread rapidly up hill and back into the orchard so that by the 
end of the summer 1910 two and one-half acres had been killed and 
approximately two acres had been taken up. 
I visited the ranch on Oct. 29th and found the barren area very wet 
and boggy in places. The mud was exceedingly sticky and so 
soft in spots that one would sink down ankle deep in walking over it. 
Such spots were usually dark brown or black in color and a little higher 
than the adjacent ground on which a deposit of white alkali had form¬ 
ed following a light snow. I was told that this was the first time 
the white alkali had been in evidence. The greater part of the barren 
area was white except for isolated elevated patches and a strip twelve 
to fifteen feet wide along the upper side which was black. All indica¬ 
tions seemed to point to the fact that the portion occupied by the white 
salts was too wet for the development of the black pigment. That 
the reader may have some conception of the violence of the attack, 
I may say that plum trees were pointed out to me which three weeks 
before were in perfect condition and now were absolutely dead. (For 
four rows back from the edge of the barren area the trees were either 
