20 
These tables indicate that the potash in this type of soil is quite 
soluble. The fixing power of this soil is far below that of the four 
soils used in the previous series; that is, the red clay soil of the 
islands is more easily saturated with potash than the other types. 
This is partly due to the low lime and magnesia content of this 
soil. The two series illustrate quite well the effect of these bases 
upon the fixation of potash. The figures in the table on page 19 
indicate the subsoil to have the power of fixing more potash than 
the soil, and that drying in the air tends to increase this power. 
ABSORPTION OF NITROGEN. 
AMMONIUM SULPHATE. 
This series was carried through similarly to the previous ammonium 
sulphate series. A table showing the solubility in distilled water of 
the ammonia nitrogen in the original soil is given herewith: 
Ammonia nitrogen removed from the soil by distilled water. 
[Expressed in parts per million nitrogen in the percolate.] 
Percolates of 100 cc. each. 
Fresh 
soU. 
Fresh 
subsoil. 
Air-dry 
soU. 
Air-dry 
subsoU. 
100 
5.1 
Trace. 
Trace. 
Trace. 
Trace. 
Trace 
7.47 
11.16 
Trace. 
5.04 
200 
6.1 
300 
7.2 
This type of soil is shown to contain only small amounts of ammonia 
nitrogen soluble in water, the amounts being slightly lower than those 
found in the previous series. 
The following table shows the absorbing power of this soil for 
ammonium nitrogen: 
Absorption of nitrogen from a solution of (NH 4 ) 2 S0 4 . 
[Expressed in parts per mUlion in the percolate.] 
SOLUTION CONTAINED 246 PARTS PER MILLION NITROGEN FROM (NH^SO*. 
Percolates of 
100 cc. each. 
Fresh 
soU. 
Fresh 
subsoU. 
Air-dry 
soU. 
Air-dry 
subsoU. 
Percolates of 
100 cc. each. 
Fresh 
soU. 
Fresh 
subsoU. 
Air-dry 
soU. 
Air-dry 
subsoU. 
100 
26.5 
65.2 
71.6 
185 
181.3 
211.5 
17.8 
54.9 
66.6 
143 
183.3 
167.4 
12.5 
113.2 
178.2 
162.3 
165.1 
172 
25.2 
111 
145.6 
149. 6 
168.9 
160 
700 
151.3 
192.9 
178.6 
239 
224 
157.1 
178.6 
152.3 
204 
242 
188 
180 
206 
188 
224 
172 
200 
800 
172 
300 
900 
184 
400 
1,000 
184 
500 
1,100.... 
214 
600 
SOLUTION CONTAINED 
204 PARTS PER MILLION NITROGEN FROM (NH 4 ) 2 SO*. 
1 200 
181.4 
211.6 
182.6 
200 
224 
206 
214 
206 
1,400 
212 
212 
206 
206 
1,300 
