Bacteriological Studies of the Fixation of Nitrogen. 31 
Table No. 3. Summary of Fixation of Nitrogen in Soils in Situ. 
Source of 
Sample 
Duration of 
Experiment 
Milligrams ni¬ 
trogen per 100 
g. soil at be¬ 
ginning. 
o 
Milligrams ni¬ 
trogen per 100 
g. soil at end. 
Milligrams ni¬ 
trogen fixed 
per 100 g. soil 
Northern Col¬ 
orado 
27 days 
107.25 
117.79 
10.54 
Central Col¬ 
orado 
30 days 
73.89 
82.11 
8.22 
Table No. g 4. Increase in Nitrogen per 100 g. of Soil. 
Source of sample 
Milligrams 
nitrogen 
Increase in nitrogen per 100 g. soil as 
Milligrams 
protein 
Milligrams 
1 month 
1 year 
1 month 
1 year 
1 1 month 
1 year 
Northern Colo¬ 
rado 
11.88 
142.58 
74.26 
891.12 
— 
72.08 
865.14 
Central Colo¬ 
rado 
8.34 
100.08 
52.12 
625.50 
50.60 
607.26 
Table No. 5 . Increase in Nitrogen per Acre-foot of Soil. 
Source of sample 
Northern Colo¬ 
rado 
Central Colo¬ 
rado 
Increase in nitrogen per acre-foot of soil as 
Pounds nitrogen 
Pounds protein 
Pounds Na NO s 
1 month 
1 year 
1 month 
1 year 
1 month 
1 year 
34,605.87 
475.26 
5,703.20 
2,970.41 
35,645.00 
2,883.82 
333.60 1 
4,003.2 
2,085.00 
25,020.00 
2,024.21 
24,290.61 
Relation of Soil Moisture to Fixation of Nitrogen in Soil. 
It has been a matter of frequent observation that where there is 
an excess of water, as in land which is unquestionably seeped, or 
v here there is a liberal coating - of white alkali on the surface, a condi¬ 
tion indicative of poor drainage, neither the brown color nor the high 
nitrates are to be found. However, along the margin of such areas 
on the higher ground where there is an abundant supply of moisture 
but not too much, we are apt to find both the high nitrates and the 
brown color. These two conditions, we have come to associate with 
the presence of the nitrogen fixing organisms in the soil, and the re¬ 
sulting nitrogen fixing power of that soil. We do not mean to say 
that they are, by any means, a necessary accompaniment, yet they are 
very often found together, and from certain experiments which we have 
made, directed especially toward this feature of the problem, we are 
led to believe that the relation existing among these three factors 
is a dependent one. 
