Fixation of Nitrogkn in Colorado Soils 47 
this place. Why the water should be confined, as it apparently 
is, to this particular area is not evident’’. I have quite recently 
endeavored to find other instances like this in that section but 
have failed. Deejier wells were sunk at this jdace without ob- 
tainino’ water and wells on neigiiliorino’ ranches yielded , 2 :ood 
water. 
These four cases that have come under my own observation 
are mentioned as possible exceptions to the claim that the ni- 
trates in the waters of shallow wells come from the surface 
soil. 
OONpERXING THE SOURCE OF THE NITROGEN IN 
THESE NITRATES 
For my views as to the source of the nitrogen and the pro- 
cess by which it is converted into nitrates, reference may be 
had to Bulletins 155 and 178 under the title ^The Fixation of 
Nitrogen in Colorado Soils”, also Bulletin 217, p. 5 et seq. and 
Bulletin 183, p. 116. 
Briefly stated, the salient features of this question are as 
follows : These spots or nitre-areas are richer in nitrogen than 
ordinary soil ; they are also very much richer in nitric nitrogen 
or corresponding nitrates than ordinary soil. Further, the 
ratio of nitric nitrogen to the total nitrogen is always high. It 
is always assumed that the conversion of proteid nitrogen into 
nitric nitrogen is a process so well established, so universal 
and so generally accepted that it is unnecessary to so much as 
make mention of it. The question to be answered is, where does 
the nitrogen, be it in the form of proteid or of nitric nitrogen, 
come from. 
My view is that it is derived from the atmosphere through 
the agency of living organisms that are capable of appropriat- 
ing the atmosnheric nitrogen to build up their nitrogenous 
components. As the azotobacter are capable of an independent 
existence and of accomplishing this, they were the first organ- 
isms to suggest themselves as the agency. 
It does not follow that other organisms may not take part 
this process; in fact, it seems very certain that there are 
Oi her organisms, either alone or in association, which may ef- 
N ct this fixation as well as the recognized azotobacter. I have 
previously explained this process as one carried out by bacter- 
ial agencies. It is much better and probably more accurate to 
use the term biological activities which I use to include mixed 
floras, as well as those which are at the same time capable of 
fixing nitrogen and of an independent existence. 
