20 
Colorado Experiment Station. 
Sample No. 24. 
A barley field on the top of a mesa was the next location chosen 
for onr work. This particular tract was selected for several reasons. 
In the first place, the nitrates had been accumulating here since 1907 
and had become so concentrated by this time, July, 1910, that the only 
place anything would grow was right along the irrigating furrows and 
even there the grain was very short and thin. Apparently the water 
in running through these had washed out a little of the nitrate from time 
to time and so had reduced the salts to a degree of partial tolerance. 
The soil on top of this mesa, for some reason, is always wet and one 
not familiar with the topography of the country would be very apt to 
suggest that the land was seeped by higher irrigation projects. As a 
matter of fact, this mesa is at least 200 feet higher than the surrounding 
country and there is no possible chance for seepage in the sense in 
which the term is ordinarily used. This peculiar condition seems 
to have resulted from excessive irrigation and a lack of proper drain¬ 
age. To use a popular expression, the soil has become “water logged.” 
The superabundance of moisture had most certainly favored nitrate 
production and the agents which were responsible for the coloring mat¬ 
ter, for the soil was as black on the surface as crude oil, and as mealy 
beneath as wood ashes. Before taking a sample, the surface crust and 
the next two inches were removed and a section, including the fourth 
to sixth inch inclusive, was obtained. This came from along an irri¬ 
gating furrow where the barley was making a feeble struggle. In cul¬ 
ture, there was almost no surface growth and only a moderate white 
deposit on the bottom and sides of the flask. A butyric odor was per¬ 
ceptible. I was rather surprised to find that after thirty days there 
was an increase of 1.68121 m. g. of nitrogen in the culture. 
Sample No. 25. 
As a source for the next sample, I selected a truck garden on the 
outskirts of a mining town. This was thirty-six miles from the nearest 
case of nitre trouble of which I had knowledge, and so far as I could 
learn nothing of the sort had ever been observed here either on the soil 
or the vegetation. The soil chosen was a very light, deep sandy loam 
which from its proximity to the river, I took to be of alluvial formation. 
All kinds of vegetables, together with strawberries, were grown here 
very successfully. The culture produced with this soil gave a heavy 
gelatinous membrane, light brown in color, and was made up almost 
entirely of Azotobacter. The increase in nitrogen in thirty days 
amounted to 5.8842 m. g. 
Sample No. 26. 
Sample No. 26 represents the soil of a young orchard in which sev¬ 
eral of the small trees on the high ground had died in 1910 and others 
were looking very suspicious. The ground was first broken in the fall 
of 1908 and set to apples in the spring of 1909. It was irrigated and 
cultivated thoroughly that season and had been irrigated for the third 
