Soiiv Changes Produced By Micro-organisms. 17 
are toxic for ammonifying bacteria when added in small quantities 
to an alkali free soil. Sodium carbonate, on the contrary, exer¬ 
cises a stimulating effect when present in amounts equivalent to .1 
per cent of the dry weight of the soil. 
The ability to produce ammonia from organic matter is a 
function common to many soil bacteria. Marchal has reported 
seventeen different species which belong to this class. Among the 
more active ammonifiers may be mentioned Bacillus mycoides, Ba¬ 
cillus proteus vulgaris, Bacillus mesentericus vulgatus, Bacillus 
subtilis, Bacillus janthinus, Bacillus coli communis, Bacillus mega- 
terium, Bacillus fluorescens liquefcciens, Bacillus fluorescens pu- 
tidus, and Sarcina lutea. 
A study of over thirty different Colorado Soils, representing 
the prevailing types to be found in the state, has shown them to 
possess exceptional ammonifying efficiency as compared with soils 
from other regions. The results obtained from six Colorado 1 sam¬ 
ples are given in the table which follows: 
Table No. 1. Ammonification in Colorado Soils. 
Source Per cent, of nitrogen converted into 
and 
ammonia in 7 days from 
100 m. g. 
Character. 
organic nitrogen as: 
Cottonseed 
Dried 
Alfalfa 
Flaxseed 
Meal. 
Blood. 
Meal. 
Meal. 
Orchard; heavy adobe clay; 
niter . 
42.31 
47.04 
12.78 
8.09 
Orchard; clay loam; niter 
51.98 
47.98 
DS.30 
1.12 
Orchard; sandy loam ; niter 
47.10 
52-64 
13.69 
.21 
Orchard; sandy loam; 
normal . 
25.92 
18.03 
12.06 
6.30 
Beet field; gravelly- clay; 
normal . 
28.02 
39-79 
2.83 
5.26 
Truck patch; silt loam; 
normal . 
21.09 
25.08 
•73 
3 - 11 
The results of this work indicate that both cottonseed meal and 
dried blood yield ammonia 
nitrogen 
readily 
under the 
action of 
our soil bacteria, and therefore they would be desirable materials to 
employ as commercial nitrogen fertilizers; the nitrogen of alfalfa 
meal appears to be about one-third as available as that of blood and 
cottonseed meal; while the nitrogen of flaxseed meal, relatively 
speaking, is almost unavailable., 
A detailed account of our ammonification investigations has 
been published as Bulletin 184 of this Station. 
