The: Ammonifying Efficiency of Certain Colorado Soils. 17 
depths in the two excavations that a brief description is necessary 
to a clear understanding and correct interpretation of the results ob¬ 
tained in the ammonification experiments. No. 23 is a sandy loam, 
more or less mealy from excessive niter; No. 24 is a mix'ture of 
sand and gravel with abundant moisture; No. 25 was taken near 
the bottom of the hole in the water bearing stratum, and consists 
of coarse sand and gravel, thoroughly saturated with water. The 
top 13 inches of soil from hole No. 2 was frozen and sample No. 
20, taken from this portion, is a sandy loam, not mealy; No. 27 is 
a clean, sharp, dry gravel with neither sand nor soil present. This 
material is so coarse that practically nothing passed through a wire 
sieve with 20 meshes to the inch, and in preparing the sample, it 
was put through a to mesh sieve instead of the usual 30 mesh; 
No. 28 is a fine, moist sand with almost no gravel. 
The ammonification results with these six soils are given in the 
the following table. 
Table No. 
i. Ammonification by Samples 
Nos. 23 
to 28. 
Per cent, nitrogen recovered as 
ammonia i 
in 7 days from: 
No. 
Source 
Cottonseed meal 
Dried blood Alfalfa meal 
Flaxseed meal 
23 
Surface 3 in. 
45.32 
30.47 
17.93 
6.20 
24 
18 to 24 in. 
48.29 
39.25 
26.27 
1.12 
25 
56 to 60 in. 
47.45 
34.04 
15.41 
.84 
26 
Surface 3 in. 
50.85 
44.76 
26.24 
9.53 
27 
18 to 24 in. 
22.62 
46.37 
34.85 
.91 
28 
56 to 60 in. 
38.53 
46.72 
28.82 
.87 
Comparing 
the results from 
•the surface 
samples 
of the two 
holes, Nos. 23 and 26, it is very clear that the excessive nitrates in 
the former have depressed ammonification. On the whole, ammoni¬ 
fication has been more active in the soils outside of the 
heavy niter area. The ammonification of flaxseed meal 
is accomplished almost entirely by the surface flora, 
this function disappearing very rapidly in the first two 
feet. Bacteria capable of ammonifying cottonseed meal, dried blood 
and alfalfa meal appear to occur almost uniformly throughout the 
first five feet. No. 24 gave the highest yields of ammonia of any 
of the samples from hole No. 1, except with flaxseed meal, due, 
possibly, to its loose, open texture. No. 27 gave the highest percent¬ 
ages of ammonia from dried blood and alfalfa meal, but was strik¬ 
ingly deficient in the microorganisms necessary for the destruction 
of cottonseed meal. No. 26 gave the largest amounts of ammonia 
from cottonseed meal and flaxseed meal. The large percentages 
of ammonia produced by Nos. 25 and 28 are worth noting in view 
of the fact that these are both deep soils in which one would hardly 
expect to find active ammonifying bacteria. 
Sample No. 29 . 
A truck garden on the outskirts of a mining town furnished 
the next sample. This soil is of particular interest since previous 
to its present ownership, it was held as a placer gold claim. The 
elevation is some 3000 feet higher than the country from which the 
