NITRATES IN THE SOIL 
By WM. P. HEADDEN 
Bulletin No. 155 of this Station, entitled “The Fixation of 
Nitrogen in Some Colorado Soils,” gives the results of our field 
observations on this subject up to the latter part of the year 1909, 
together with those obtained in the laboratories in more detail than 
is absolutely necessary for a general understanding of the subject. 
The people in many sections of this State understand per¬ 
fectly well what is meant by the expression “brown spots.” This 
expression was more appropriate a few years ago than at the present 
time, for then the term spot described quite accurately the area 
involved, as it does in some instances today. There are, at this 
time, however, areas measured by acres, which the term does not 
describe. What was five or six years ago a spot has now grown 
to involve as much, perhaps, as six, eight or more acres, and the 
use of the term spot is justified only on the ground that it was at 
first used to describe a condition as well as an area. 
The condition which it describes is well known to the people 
of some sections of the State where it appeared a long while ago 
as barren places, or spots, the surface of which had a brown color. 
Sometimes they were shining and looked as though they were wet or 
perhaps oily. Some of the worst spots to which my attention has 
been directed appeared as though they had been wetted with a 
thick, black oil. The fact that nothing grew on these spots has been 
used by many correspondents as descriptive of them. These spots 
occur in a great variety of soils, from heavy adobe to light, sandy 
loams and silts. The spots are only local and exaggerated ex¬ 
pressions of a condition which is becoming quite general. I have 
met persons who really knew but little about the matter, though 
they assumed to know a great deal, and who have insisted that 
these were seepage spots. It is true that a regular and fairly abund¬ 
ant supply of moisture seems to be a very favorable factor in the 
development of this condition, but I have not observed it anywhere, 
where there is an excess of moisture, especially at the surface. In 
some extremely bad places, I have found a very peculiar condition 
of the ground, beginning at depths varying from a few inches to 
two and a half feet below the surface which I cannot describe in 
any other way than as muddy. This ground is very soft and wet 
but retains the water so persistently that the water runs out of it 
very slowly, or so good as not at all. On the surface of such lands 
we often find a thin crust and just beneath this a mealy mass, some¬ 
times as much as three inches thick. This brown color is by no 
means always associated with this wetness of the soil but is gener- 
