The Fixation oe Nitrogen. 15 
in the first foot 1.86, in the second 2.09 and in the third 1.509 
percent—which the analyses show to be very largely calcic sulfate. 
These statements, as well as the following considerations, apply 
to every individual case considered in this bulletin. The ground 
waters are wholly inadequate to transport the nitrate, for we have 
no 120 acre-feet of ground water per annum nor is there any 
land surface from which to obtain the nitrates. The whole of the 
irrigated lands in some sections are more or less affected and it is 
wholly gratuitous to even suggest our native prairies and mountain 
sides as a source of these nitrates. Our river waters, even those 
used for irrigation, contain very little nitric nitrogen from 0.00 to 
0.4 p. p. m. Our virgin soils show only 8.000 p. p. m. of nitric 
nitrogen as a maximum—and even this is subject to appropriation 
by plants and reduction in the soil, so that even though very large 
areas were to be leached out or washed off this source could scarcely 
be soberly appealed to as the source of these nitrates. 
Case No. 7— This orchard showed the first bad burning about 
the middle of May, 1909, shortly after the orchard had been heated 
to protect the crop against frost, about April 27. The trees had 
continued to grow steadily worse and the owner at first feared 
that the injury was due either wholly or in part to the gases given 
off during the combustion of the coal used in heating the orchard. 
To this question there was a very direct answer, i. e., the water 
sprouts which had grown since the heating were burning badly. 
This orchard presents, in regard to soil conditions, a strong 
contrast to the last one mentioned, and to all others heretofore 
mentioned, except Orchard No. 5. The soil is sandy, inclining 
in some parts of the orchard to a clayey loam. The attack began 
a little to the east of the center of the orchard. This part of the 
orchard is not lower than the rest of it. The owner has sprayed 
very heavily some seasons and is still a heavy sprayer. There 
were some girdled trees in the orchard but the arsenic had nothing 
to do with the burning. This burning is quite distinct from a 
spray burn. We dug a hole near to one of the burned trees five 
and one-half feet deep. The orchard had been recently irrigated 
but we found no more than a desirable degree of moisture at this 
depth. A sample of soil was taken at this time. The depth to 
which it was taken is not stated in my notes. The water-soluble 
equaled 0.187 percent. No analysis was made of this material 
beyond a nitric acid determination which showed an amount corre¬ 
sponding to 5.412 percent of sodic nitrate or 0.01 percent of the 
air-dried soil, a small amount, still it equals about 22 pounds to a 
tree taking the soil to a depth of two feet. The family is supplied 
with water stored in a cistern which is 10 feet deep. I was in¬ 
formed that they did not strike water in digging it. The age of 
