The Ammonifying Efficiency of Certain Colorado Soils. 19 
other samples were obtained, and the tract is 36 miles from the near¬ 
est recorded case of niter. The soil is a deep river bottom silt loam 
and is in a most productive condition, the owner having obtained 
240 sacks of potatoes per acre in 1911. All kinds of vegetables, to¬ 
gether with strawberries, are grown here very successfully. The 
soil has been heavily manured, and for that reason, I expected to 
find it abundantly stocked with all kinds of ammonifying bacteria. 
My expectatons were not fulfilled, however, for the ammonifying 
efficiency was less than any of the other soils examined and only 
about half as great as the general average for the niter soils. From 
cottonseed meal, 22.49% °- the nitrogen was recovered as ammonia; 
dried blood 26.48% ; alfalfa meal 2.13% ; flaxseed meal 3.11%. 
Samples Nos. 30 and 31. 
These soils were taken from an entirely different part of the 
state than any of the others and come from a sugar beet field where 
very interesting soil conditions maintain. The tract, as a whole, 
is on high ground, but slopes rather rapidly from all sides into a 
hollow or basin near the center. This is wet and white with alkali much 
of the time. Between this part and the higher surrounding portion 
lies a zone which slopes gently toward the basin proper. Although 
planted to beets for two successive years, none have grown next 
to the white alkali at any time, and during 1911 none grew any* 
where in this zone, not even at a considerable distance from the 
alkali, where a stand had been obtained in former years. The soil 
in this belt was brown, encrusted, and mealy, but not white. Im¬ 
mediately adjacent to the white alkali, it was wet and muddy, but 
the belt proper carried about the optimum amount of moisture for 
growing crops. The boundary of the white area appears to remain 
about the same from year to year, but the surrounding brown zone 
is moving gradually up the slope a little farther each year, the pro¬ 
gress for 1911 having been at least 100 feet. With the advancing 
line of nitrates, the beets have been forced to recede, and each year 
the limit for their growth is set a little farther back. Sample No. 
30 was collected from the brown, mealy niter zone where nothing 
grew, and No. 31 from that part of the field where there was a good 
Table No. 3. Nitrogen as Ammonia Originally Present in 100 Grams 
of Soil. 
Soil 
Milligrams Nitrogen 
Soil 
Milligrams Nitrogen 
Soil 
Milligrams Nitrogen 
No. 
as Ammonia 
No. 
as Ammonia 
No. 
as Ammonia 
1 
.4203 
11 
.9807 
21 
.8406 
2 
.7005 
12 
.8406 
22 
.8406 
3 
.4203 
13 
1.1208 
23 
.2802 
4 
.2802 
14 
.1401 
24 
0.0000 
5 
.4203 
15 
.5604 
25 
.1401 
6 
.7005 
16 
1.2609 
26 
0.0000 
7 
.2802 
17 
0.0000 
27 
0.0000 
8 
.1401, 
18 
2.6619 
28 
0.0000 
9 
1.2609 
19 
.7005 
29 
3.5025 
10 
1.1208 
20 
.9807 
30 
.4203 
31 
1.2609 
