21 
Summary of preceding table. 
Soil. 
Fresh soil 
Fresh subsoil . . 
Air-dry soil 
Air-dry subsoil 
Nitrogen 
added to 
100 gm. 
soil. 
Gram. 
0.3318 
.3318 
.2706 
.2706 
Nitrogen 
fixed Dy 
100 gin. 
soil. 
Gram. 
0.1000 
.1164 
.0916 
.1019 
Per cent 
of 
nitrogen 
fixed. 
30.1 
35 
33.9 
37.6 
Since ammonium salts are retained by the soil in most respects by 
the same reactions which govern the absorption of potash, we would 
expect the red clay soil to have the low absorptive power shown in 
the above table, which is less than one-half that of the soils used in 
the previous series. The subsoil showed a slightly higher fixing 
power than the soil, while the effect of drying in the air was to reduce 
the fixing power. This latter rinding is just the reverse of that 
obtained in case of potash. 
SODIUM NITRATE. 
The absorbing power of this soil for sodium nitrate is very much 
lower than that of the other types, as may be seen from the following 
tables : 
Removal of nitrate nitrogen from soil by distilled water. 
[Expressed in parts per million of nitrogen in the percolate.] 
Percolates of 100 cc. each. 
Fresh 
soil. 
Fresh 
subsoil. 
Air-dry 
soil. 
Air-dry 
subsoil. 
100 
19.2 8.8 
12.8 
7.2 
200 
1 
Absorption of nitrogen from a solution of 250 parts per million nitrogen from NaNO z . 
[Expressed in parts per million of nitrogen in the filtrate.] 
Percolates of ! 
100 cc. each. 
Fresh 
soil. 
Fresh 
subsoil. 
Air-dry 
soil. 
Air-dry 1 
subsoil. 
Percolates of 
100 cc. each. 
Fresh 
sofl. 
Fresh 
subsoil. 
Air-dry ! Air-dry 
soil. subsoil. 
100 
187.5 
250 
180.0 
255 
215.0 
240 
215.0 
240 
300 
250.0 
250 
250.0 
250 
250.0 250.0 
200 
1 
400 
2.50 250 
Summary of above table. 
Soil. 
Nitrogen Nitrogen 
added to fixed bv 
100 gm. 100 gm". 
soil. soil. 
Per cent 
of 
nitrogen 
fixed. 
Gram. Gram. 
Fresh soil 0. 1000 0. 0062 
Fresh subsoil 1000 . 0065 
Air-dry soil 1000 . 0045 
Air-dry subsoil 1000 . 0045 
6.2 
6.5 
4.5 
4.5 
