i6 
Colorado Experiment Station. 
ground planted to corn. This stand was very poor. Much of it 
died in the ground shortly after germination, while some that did grow, 
attained a height of 8 to io inches, with sickly yellow leaves and finally 
died. By the end of fall, 1910, approximately 300 trees had been 
taken out and consigned to the brush heap and wood pile. I have 
learned recently that the remaining acre and a half began dying so 
rapidly this spring (1911) that it, too, was grubbed out. Thus, the 
complete ruin of the seven acres was brought about in less than two 
years. The soil is a sandy loam, underlaid with gravel at 5 to 8 feet. 
There is no water near the surface. The characteristic brown color 
was plainly visible on the crests and sides of the irrigation furrows and 
it was from one of these that I took the top three inches of soil for ex¬ 
amination. Azotobacter developed readily in culture with the char¬ 
acteristic membrane and after thirty days an increase of 4.13295 m. g. 
of nitrogen was secured. 
Sample No. 14. 
The next sample was procured from an orchard where only a 
few trees showed signs of firing in the early summer of 1910. I visited 
this place in July, 1910, and it took considerable diligent hunting to 
find the few scattering trees which were suffering. There were per¬ 
haps twenty in all. Today six acres of this orchard are dead from no 
other cause than nitre. There was no water at five and a half feet 
and the soil was a nice clay loam. The sample for the fixation test 
was taken from between two rows of trees which seemed to be as badly 
affected as any and included the surface three inches. The ground be¬ 
tween the trees had been recently cultivated so that any brown stain 
which might have been visible on the irrigating furrows had been ob¬ 
literated. There was no indication of excessive nitrates in the soil 
other than the burned edges of the apple leaves. Pure cultures of 
Azotobacter were isolated readily from this soil which gave an increase 
of 6.65475 m. g. of nitrogen in thirty days. 
Sample No. 15. 
While looking over the orchard described above I was asked to 
pass an opinion on some apricot trees in a neighboring orchard. They 
were large trees, seven in number, and affected in a most peculiar way. 
The foliage of the entire tree was wilted as if the water supply was 
cut off; the leaves had a good green color and there was a heavy set of 
fruit which was just beginning to ripen. A short distance from the 
trees, I discovered the brown color on the soil which we have come to 
regard as an important symptom of the nitre trouble. I set about at 
once to look for signs of this on the apple foliage nearby, and before 
I had gone far, my search was rewarded. The number of trees involved 
was limited to possibly a dozen and these were not burned severely. 
However, bv the end of the season, all of these had died and were taken 
up, leaving about a quarter of an acre barren. There was some indica¬ 
tion of too much water in this orchard and it is very possible that the 
