Oct. 8, 1917 
Nitrate-Nitrogen Accumulation in Soil 
57 
soil as well as in excess of any accumulations observed under field 
conditions. 
The moisture content per 100 gm. of soil, incubation period, etc., are 
given below, along with results reported as milligrams of N 0 3 per 100 
gm. of soil gained or lost. A sample containing the same quantities of 
ammonium sulphate and calcium carbonate was also incubated in 
tightly stoppered bottles, to simulate conditions of loose soil below the 
unbroken column, provided no oxygen diffused through. 
Table VIII .—Nitrate accumulation in unbroken and sieved columns of soil 
[Results expressed as gain or loss in milligrams of NO3 per 100 gm. of soil] 
Sample 
No. 
1. 
2 . 
3 - 
4 - 
5 - 
6 . 
7 - 
8 . 
9 * 
10 
Depth of 
column. 
Condition. 
Moisture 
content. 
Inches . 
7 
7 
7 
7 
5 
7 
7 
7 
7 
7 
Unbroken. Incubated 7 weeks. 
Sieved, incubated 7 weeks. 
Unbroken. Incubated 4 weeks. 
Sieved, incubated 4 weeks. 
Unbroken. Loose soil below incubated 4 
weeks. 
Moistened with ammonium sulphate, in- 
bated 4 weeks. 
Sieved, moistened with ammonium sul¬ 
phate, incubated 4 weeks. 
Sieved, moistened with ammonium sul¬ 
phate, sealed, incubated 4 weeks. 
Unbroken. Incubated 12 weeks. 
Sieved, incubated 12 weeks. 
C. c, 
25 
25 
24 
24 
24 
24 
24 
24 
24 
24 
Gain or 
loss. 
9. 60 
6. 50 
•32 
.07 
39 - 80 
i 4 - 5 ° 
30. 00 
-. 90 
2. 50 
1. 60 
It will be observed that the oxygen contained in the loose soil was 
insufficient to prevent dentrification, also that oxygen passed to the loose 
soil below the 5-inch column in sufficient quantity to enable a more 
rapid accumulation of N 0 3 than occurred in loose soil freely exposed 
to the air. The accumulation in the 7-inch column moistened with 
ammonium sulphate is also far in excess of that where no nitrogen was 
added. 
DISCUSSION OF RESULTS 
The results presented above are certainly sufficient to open the question 
of whether or not the beneficial effect upon bacterial activity, observed 
to follow cultivation, can be attributed to increased aeration. The 
question is not altogether new, for Leather (8) has pointed out that the 
beneficial effect of cultivation upon crop production must be attributed 
to some factor other than aeration. 
The available data relative to the effect of different degrees of aeration 
upon nitrate formation is confined almost wholly to the effect that 
cultivation produces. We do not believe, however, that one is justified 
in attributing the major effect of cultivation upon nitrification to better 
aeration. There is no question but that cultivation may beneficially 
influence nitrate formation other than through increasing aeration. Be 
