THE NITRIFYING EFFICIENCY OF CERTAIN COLORADO SOILS 
35 
the carbonate sample. All of these negatively reacting soils contained 
the necessary nitrifying organisms as manifested by the appreciable 
gains that the checks made. There seems to be little doubt in the case 
of the five soils just mentioned that the ammonium carbonate has ex¬ 
ercised some toxic action, thus preventing the normal development 
of the nitrifying flora. 
The ammonium carbonate appears to have improved conditions 
for nitrification very much for Sample No. 69, for it gave a net gain 
of 450 p. p. m. of nitric nitrogen as compared with 70 p. p. m. in the 
preceding series. 
TABLE NO. 6.—Nitrification of Ammonium Carbonate by Foreign Soils. Nitrogen in Parts Per Million 
of Air-dried Soil as Nitrites and Nitrates from 100 m.g. Nitrogen as (NH 4 )„C0 3 
Duration of Experiment: 6 Weeks at 28 Degrees C. 
Nitrogen as nitrites Nitrogen as nitrates Chlorin 
r o i j in parts per million in parts per million in 
Number of Sample and _ a _ _1_a _n n m 
Description 
52 Corn field, clay loam, 
Check 
at 
begin. 
Check 
at 
end 
(NH ) 2 C0 3 
added 
Check 
at 
begin. 
Check 
at 
end 
(nh 4 ) 2 co 3 
added 
Total 
gain 
Net 
gain 
Ohio . 
53 Pine forest, gravelly 
.002 
.176 
Trace 
7.0 
60. 
200. 
193. 
140. 
8. 
loam, Georgia. 
54 Apple orchard, loam, 
T race 
.220 
.08 
5.0 
Trace 
5. 
0 . 
5. 
78. 
Washington . 
55 Apple orchard, heavy 
.04 
.340 
.08 
5.0 
90. 
280. 
275. 
190. 
40. 
clay, Virginia. 
56 Cotton field, sandy 
Trace 
.160 
.02 
9.0 
70. 
320. 
311. 
250. 
74. 
loam, Okla-noma . . 
57 Water melons, sandy 
loam, North Carolina 
58 Cotton field, sandy 
.18 
.168 
.04 
11.0 
50. 
240. 
229. 
190. 
8. 
Trace 
.168 
.14 
7.0 
46. 
6. 
— 1 . 
—40. 
10. 
loam, Texas . 
59 Cotton field, clay 
.12 
.160 
Trace 
7.0 . 
50. 
240. 
233. 
190. 
98. 
loam, Georgia .... 
60 Corn field, clay, 
Trace 
.152 
Trace 
14.0 
60. 
240. 
226. 
180. 
106. 
North Carolina .... 
61 Tobacco field, sandy 
.16 
.112 
Trace 
6.0 
70. 
360. 
354. 
290. 
8. 
loam, N. Carolina... 
62 Vineyard, clay loam, 
Trace 
.100 
.12 
3.0 
20. 
3. 
0 . 
—17. 
6. 
California . 
63 Alfalfa field, sandy 
Trace 
Trace 
30.00 
4.0 
24. 
4. 
0 . 
—20. 
26. 
loam, California . . 
64 Small grain, sandy 
.04 
.100 
26.00 
4.0 
46. 
40. 
36. 
—6. 
8. 
loam, California . . 
65 Cotton field, sandy 
.88 
.320 
.32 
6.0 
70. 
160. 
154. 
90. 
8. 
loam, Arkansas .... 
66 Cane field, clay loam, 
.60 
.132 
30.00 
4.0 
24. 
120. 
116. 
96. 
62. 
Oklahoma . 
67 Mixed orchard, silt 
.18 
.136 
.26 
40.0 
126. 
240. 
200. 
114. 
6. 
loam, California. . . . 
68 Plum orchard, sandy 
1.80 
1.800 
74.00 
120.0 
140. 
200. 
80. 
60. 
700. 
loam, California.... 
69 Virgin soil, clay, Cali- 
.26 
.140 
74.00 
7.4 
40. 
50. 
42.6 
10. 
8. 
fornia . 
70 Small grain, black 
Trace 
.100 
.88 
2.0 
30. 
480. 
478. 
450. 
8. 
adobe, California .... 
71 Raw cactus land, sand 
1.40 
.160 
.04 
5.0 
34. 
640. 
635. 
606. 
10. 
and gravel. Calif. 
73 Vinevard, sandy loam, 
Trace 
.120 
.32 
0.0 
12. 
0 . 
0 . 
—12. 
6. 
California . 
74 Sugar beets, sandy 
0.0 
.120 
.10 
7.4 
70. 
320. 
312.6 
250. 
8. 
loam, Kansas . 
1.20 
.260 
.12 
26.0 
160. 
700. 
674. 
540. 
2,000. 
Nos. 67 and 68 each produced 74 p. p. m. of nitrite nitrogen 
and Nos. 62, 63, and 65 gave 3P, 26 and 30 p. p. m. respectively. 
In the writer’s opinion, these are to be regarded as an indication of 
interrupted and retarded nitrification rather than of reduction. 
