The Ammonifying Efficiency of Certain Colorado Soils. 
i3 
years, particularly to bearing apple orchards. This sample comes from 
such a place, where it was thought at first that the injury was due to 
faulty drainage. Accordingly, in 1910, an experienced engineer was 
employed to put in the proper amount of tile at the correct depth, but 
the trees have continued to die in spite of the drain. Practically two 
of the seven acres of this orchard are worthless today. Many of the 
trees were dead outright when I saw the place last fall, while others 
were struggling along with just life enough to put out a dwarfed, 
stunted foliage. The soil is a sandy loam and was collected near a 
burning tree, October 24, 1911. The ammonification tests give the 
following percentages of nitrogen recovered as ammonia in seven days: 
From cottonseed meal 49.07% ; dried Food 50.78% ; alfalfa meal 
15.86% ; flaxseed meal 1.82%. 
Sample No 16. 
This sample was obtained from an orchard in the same region as 
Number 15, but not adjoining it. The soil is a red, sandy loam, and be¬ 
cause of this peculiar color it has always been rather difficult to de¬ 
tect any brown discoloration, although there is no question about the 
excessive nitrates for nearly twenty acres of bearing orchard have been 
ruined since 1910. Here, as in the preceding orchard, the trees appear 
to be dying gradually rather than going in one season as is the case so 
often. Near the farm house where the surface of the soil has not been 
disturbed by cultivation, the characteristic brown color and mealy con¬ 
dition are quite apparent. The nitrogen fixing power of this soil in 
1910 amounted to 7. 1451 m. g. of nitrogen per 100 c. c. manite solution 
in thirty days. The ammonification experiment gave the following 
amounts of nitrogen recovered as ammonia in seven days: From cot¬ 
tonseed meal 47-10% ; dried blood 52.64% ; alfalfa meal 13.69% ; flax¬ 
seed meal .21%. 
Sample No. 17. 
After giving considerable attention to the biological activities in 
cultivated soils, I was interested in knowing whether raw adobe Fay, 
which had never received any cultivation, and which had never been 
disturbed since the time it was formed by the weathering of the under¬ 
lying shale possessed any ammonifying powers. A previous examine 
tion for Azotobacter had failed to show the presence of this genus. To 
this end, I selected an adobe hill where this type of topography pre¬ 
vailed, in a section of the couni ry where agriculture was absolutely 
out of the question. The hill was about eight miles from the nearest 
town, a half mile from the wagon road, inaccessible, and arose abruptly 
from the edge of a stream to a height of 150 to 200 feet. Because of 
its location, I doubt if many human beings had ever ascended it, and, in 
fact, 1 see no reason for anyone to have done so unless on -t mission 
similar to mine. There was no vegetation whatever upon it, and aside 
from a few bird tracks and one lonely spider, !. saw no evi lence of 
animal visitations. While collecting my sample from the highest 
point of the hill, I noticed numerous pockets of white crystals, pre- 
