The Fixation oe Nitrogen. 5 7 
that the seepage and drain water from this area contain nitiates 
enough to account for all the nitrates which we found in the shales 
which actually underlie this mesa. 
Case NO. 20— On page 19, Bulletin 155, I gave a very brief 
description of the conditions obtaining in the field where our Labor¬ 
atory No. 680 was collected. I mention it again merely to give 
the salient features of its condition in 1910, a little over two years 
after that sample was taken. The land was described as having 
been an oat field in 1907; the surface was stated to be puffed up and 
mealy. A sample taken to a depth of two inches yielded 5.42 
percent of water-soluble salts salts which contained nitric acid 
equivalent to 21.719 percent of sodic nitrate. This land was in 
very bad condition in 1909 and barren in 1910. Of the original 
25 acres more than 15 acres (estimated) has been rendered value¬ 
less by the combined effects of the seepage and nitrates. What the 
seepage has not ruined the nitre has, with the exception of possibly 
ten acres or less. The following four samples were gathered in 
September, 1909. No. 837 was gathered from a portion of the 
field where the water had probably done no damage, but wheie 
there was much white alkali. The water-soluble equalled 12.96 
percent of the air-dried sample. My field notes mention the fact 
that the brown spots appear on the outer or upper edge of the white 
alkali. This is a sample of such material as occurs in these mixed 
spots. No. 839 is a soil sample taken from beneath a brown spot 
after the surface portion had been removed. The sample repre¬ 
sents six inches of soil, five to ten inches inclusive. The watei- 
soluble equalled 12.67 percent. Nos. 841 and 842 are samples of 
the “black alkali” from different places in the field. The water- 
soluble equalled 10.30 and 10.40 percent respectively. This land, 
where these samples were taken, was still in pretty good condition 
in February, 1908, but in September, 1909, the land was already 
in bad condition, and in July, 1910 I have entered the note that 
this land was ruined. There still remained from five to se^ en 
acres of winter wheat which was very fine indeed. No samples 
were taken in Tuly, 1910, because a very heavy rain had fallen oniv 
a few hours before my visit. 
