15 
The following table shows the absorbing power of these soils for 
nitrate nitrogen, using a solution of sodium nitrate which contained 
250 parts per million of nitrogen: 
Absorption of nitrogen from a solution of NaN0 3 . 
[Expressed in parts per million of nitrogen in the percolate.] 
Percolates of 
100 cc. each. 
SoU No. 
292. 
SoU No. 
448. 
Soil No. 
428. 
Soil No. 
474. 
Percolates of 
100 cc. each. 
SoU No. 
292. 
Soil No. 
448. 
SoU No. 
428. 
Soil No. 
474. 
100 
147 
184 
215 
245 
240 
225 
205 
230 
230 
157 
162 
190 
240 
245 
220 
205 
240 
225 
142 
180 
180 
205 
225 
220 
215 
215 
225 
290 
170 
200 
235 
235 
200 
195 
220 
175 
1,000 
240 
240 
230 
240 
245 
250 
250 
250 
250 
225 
230 
235 
235 
240 
245 
250 
250 
250 
230 
230 
235 
240 
240 
250 
250 
250 
195 
200... 
1,100 
185 
300... 
1,200 
215 
400... 
1,300 
215 
500... 
1,400 
215 
COO... 
1,500 
220 
700 
1,600 
225 
800 
1,700 
900 
1,800 
Summary of above table. 
Soil No. 
Nitrogen 
added to 
100 gm. 
sorl. 
Nitrogen 
fixed by 
100 gm. 
soil. 
Per cent 
of nitro- 
gen fixed. 
292 
Gram. 
0.4500 
.4500 
.4250 
. 4000 
Gram. 
0.0384 
.0456 
.0518 
.0610 
8.5 
10 
448 
428 
12 
474 
15 
The above table presents some very interesting data. It is quite 
generally conceded that soils have no fixing power for nitrates and 
for this reason it is difficult to explain the action of soil No. 474 
toward this salt. The percolation was very slow in this instance 
and the rate decreased to such an extent that the series had to be 
stopped after 1,600 cubic centimeters had passed through, as the 
solution would no longer filter through the column. This condition 
exists in spite of the fact that the soil contained only an extremely 
small percentage of clay. Soil No. 428 acted somewhat similarly, 
but percolation did not stop completely as in the case of No. 474. 
This condition is undoubtedly brought about by the action of sodium 
nitrate upon the organic matter, as both of these soils were high in 
this constituent. Soil No. 474 was apparently still fixing nitrogen 
at the close of the experiment, as in no case except with the first 100 
cubic centimeters did the percolate reach a concentration of 250 
parts per million. These figures indicate that while soils are unable 
to retain nitrates against the action of nitrate-free water, they are 
able to retain limited amounts against the action of water with a 
high nitrate content. It is possible that considerable denitrification 
took place in soil No. 474. The sluggish movement of the solution 
through this soil indicates the existence of just the conditions which 
are conducive tp denitrification. The same is true of No. 428. 
