The) Fixation of Nitrogen. 53 
to be in harmony with my views or not. The quantity of soluble 
salts in this surface, mealy soil is exceptionally high and contains 
an unusually large amount of organic matter for our samples. In 
judging this amount and the effects of the salts in this sample it 
must be borne in mind that it was taken to represent the surface 
portion only and the fact that I possibly got some portion of the 
sample at a depth of two inches was an accident due to the fact that 
I took it with a round-pointed shovel. The great bulk of the 
sample was made up of the mealy, almost dry, surface portion. 
This did not form an incrustation of effloresced salts, as we often 
find where the common white alkali prevails. Professor Sackett 
tells me that the soil extract made from the surface sample which 
he took failed to develop azotobacter in his culture medium. They 
had probably been killed as well as the other plants due to the con¬ 
centration of the salts. This is not the only sample in which this 
has been found to be the case. In the case of Orchard No. 2, Bul¬ 
letin 155, pages 13 to 17, we found this to be true. Samples from 
the surface of excessively bad portions gave no development of 
azotobacter, whereas samples from below the surface or at or 
near the edge of the bad territory gave a very abundant develop¬ 
ment. It is therefore, quite what might be expected, i. e., to find 
this ground, so extremely rich in soluble salts, devoidof azotobacter. 
The following samples are from the same section of country 
but not from the same place. No. 590 and 595 are from the same 
place but 981 is from another, a mile or possibly more north of it. 
I used the term spots in describing these occurrences in Bulletin 
1 55 and again spoke of the nitrates occurring in almost continuous 
but irregular areas, but have not deemed it necessary to give 
analyses of alkalis and soils outside of these areas except in Case 
8, as the amount of the nitrates are so unusual that I have deemed 
it unnecessary. Samples 590 and 595 are from the same piece of 
land and taken not far from each other on the same date. They 
were both originally taken as samples of alkalis, as we were study¬ 
ing, at that time, the effects of alkalis and the maximum amount 
of them compatible with good crops, etc. 
The water-soluble equalled in 590, 7.57, in 595, 33.33 and in 
981, 28.44 percent. Samples 590 and 595 were collected in 1907 
and 981 in 1910. 
