4§ The; Colorado Expe:rime:nt Station. 
considered these possibilities, but I have failed to see how these 
theories of accounting for the presence of nitrates, never before 
met with in arable soils in such quantities and over such large 
areas, so far as I know, apply to these cases and especially to Case 
8, which, as is stated in the presentation of it, is of all the cases 
discussed probably the one most favorable for the application of 
these usual explanations. 
4 his is by no means the only instance of the occurrence of 
nitrates in this immediate neighborhood but it is the best example 
of the general effects of the nitrates in ground that we would 
usually consider almost entirely free from any objection that I can 
recall. There are very much more severe cases of this trouble in 
the neighborhood but the land is not so well located for orchard 
culture. One of the most striking cases in point was a ffve-or 
eight-acre orchard planted on ground that sloped toward a slight 
depression. A deep drain ran at the base of the slope and two lines 
of underdrain, six feet deep, extended up into the orchard. We 
dug a hole three and a half feet deep at a point which I thought 
a fa\ 01 able one to find water but I found none. At three and a 
half feet we encountered a stratum of marl and below this there is, 
as show n by the ditch and drains referred to, a coarse gravel with 
some marl. The surface of this ground was very brown and 
mealy. The trees on July 18, 1910, were burning very badly 
and many of them were already dead. The owner stated that they 
began to die during the season of 1909, but I did not learn whether 
the trouble began in the spring or summer. 
A number of other instances of trees similarly located could 
be mentioned. In some section of our orchard districts it is diffi¬ 
cult to find an orchard which does not show more or less of the 
trouble at some time during the season. The trees that are at all 
seriously affected seem to have no recuperative power. 
CaS6 No. 18 1 his case, like several others, presents more 
than an orchard, but as an orchard is actually involved I have 
retained the designation. This is quite fully justified not only 
because a part of the land is set to apple trees but also because thev 
present a marked case of this trouble. The case is an involved 
one; in part of the land there is an excess of water, in other 
portions the soil is shallow, a stratum of marl coming near to the 
surface,, but in other portions the conditions are good, or fairly 
so. It is exclusively of the better part of the orchard that I shall 
write. The trees were twelve years old the first time that I saw 
them, now going on three years ago, and so far as I have been 
able to learn they had not at that time shown any of this trouble, 
though I took a sample of soil on my first visit to the orchard in 
order to test it for nitric acid. This sample contained 2.126 percent 
