442 
PACIFIC SCIENCE, VoL VII, October, 1953 
TABLE 2 
The Average Bulk Density and Particle Density of a Series of Ferruginous Laterites 
AT Different Degrees of Hardening 
AVERAGE 
samples from 
SAMPLES FROM 
SAMPLES FROM 
PROFILES 
SAMPLES FROM 
CRUST 
HARDENED SOIL 
HAVING VEGETATION 
FRIABLE SUBSOIL 
Bulk density 
2.13 
1.33 
0.91 
0.95 
Particle density 
4.13 
3.87 
3.01 
2.46 
layer of both profiles showed practically no 
difference in their loss of weight on ignition, 
being 26 and 28 per cent. 
The content of iron and titanium oxides 
is the highest in the soil from the 0-5 -inch 
and 5-10-inch layers of the profile of the 
barren area, while the 10-1 5 -inch layer of both 
profiles has a very similar amount of these 
oxides. The aluminum oxide content of soil 
from the 0-5 -inch and 5-10-inch layers of the 
profile with the vegetative cover is higher 
than that for the corresponding soil layers of 
the profile from the barren area. The soils 
from the profile with a vegetative cover are 
less acid than the soils from the 'barren area. 
In the former the soil reaction ranges from 
pH 4.4 to 4.6 and in the latter from pH 3.8 
to 4.2. 
In Table 4 the data obtained from the ana- 
lysis of cation exchange capacities of the soil 
are given. The cation exchange capacity of the 
soils shows the same relationship as the loss 
on ignition. The soil from the surface horizon 
of the profile from the area having a vege- 
tative cover has a much higher exchange capa- 
city than that from the surface horizon of the 
profile from the barren area, being 41.0 and 
3.7 milliequivalents per 100 grams, respective- 
ly. Likewise, a difference existed in the 5-10- 
inch layer of the two profiles in which the 
cation exchange capacities were 37.0 and 15.6 
milliequivalents per 100 grams, respectively. 
The cation exchange capacities of the 10-15- 
inch layer were very similar, being 38.4 and 
34.9 milliequivalents per 100 grams. The or- 
ganic matter content of the soil with a 
vegetative cover was higher than that found 
in the barren area. The organic matter content 
is not of sufficient quantity to explain this 
change in cation exchange capacity, so de- 
TABLE 3 
The Chemical Composition of Laterite Profiles; a Comparison of Effect of Dehydration 
Due to Exposure on Chemical Composition 
LOSS ON 
DEPTH 
pn 
Si02 
A1203 
Fe203 
Ti02 
IGNITION 
Soil with vegetative cover (no crust) 
Inches 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
0- 5 
4.6 
7.50 
13.00 
41.80 
6.03 
27.92 
5-10 
4.6 
7.84 
15.45 
40.99 
6.29 
26.78 
10-15 
4.4 
14.78 
22.60 
27.40 
4.34 
28.53 
Barren soil (crust) 
0- 5 
3.8 
6.46 
4.13 
56.02 
31.02 
2.06 
5-10 
4.0 
5.68 
9.46 
60.63 
11.87 
10.23 
10-15 
4.2 
13.01 
22.58 
32.10 
5.67 
25.72 
