Dolomitization in Hawaiian Soils — Sherman et al. 
41 
In Table 3 are given the data obtained for 
the quantities of exchangeable cations in the 
soil from the different parts of the soil pro¬ 
file. The quantity of exchangeable calcium 
was found to be markedly greater in the soils 
from the part of the profile which showed 
the accumulation of gypsum. In this part of 
the profile, calcium amounted to 80 to 90 
per cent of the total exchangeable cations in 
the soil, whereas in the soil above the zone 
of gypsum accumulation it amounted to 72 
per cent of the total exchangeable cations. 
Exchangeable magnesium showed an oppo¬ 
site relationship, since it amounted to 25 per 
cent of the total exchangeable bases in the 
soils of the profile above the zone of gypsum 
accumulation and in the gypsum zone it ac¬ 
counted for 9 per cent of the cations. The 
ratio of exchangeable calcium to magnesium 
was the lowest in the soils above the zone of 
gypsum accumulation. The quantity of ex¬ 
changeable potassium and sodium found in 
the soils of this profile was small, amounting 
to less than 4 per cent of total exchangeable 
cations. 
The results of the analysis of the carbonate 
fraction are given in Table 4. The amount 
of total carbonates found in any soil horizon 
of this profile was not great. Analysis of 
carbonates in the soils of this area has failed 
to show a zone of carbonate accumulation in 
TABLE 3 
The Quantity of Exchangeable Cations and the Percentage of Each Cation of the Total 
Exchangeable Cations in a Lualualei Valley Soil Which Contains Dolomitic Carbonates 
DEPTH 
OF SOIL 
EXCHANGEABLE CATIONS IN M.E. 
PER 100 GM. 
PERCENTAGE OF TOTAL 
EXCHANGEABLE CATIONS 
Ex¬ 
RATIO 
SAMPLES 
change 
capacity 
Ca 
Mg 
K 
Na 
Ca:Mg 
Ca 
Mg 
K 
Na 
inches 
0-6 . . 
65.8 
48.0 
15.8 
1.4 
0.6 
3.04 
72.9 
24.0 
2.1 
1.0 
6-12 . . 
57.2 
40.8 
14.5 
1.0 
0.9 
2.81 
71.3 
25.3 
1.7 
1.6 
12-18 . . 
54.9 
39.3 
14.2 
0.5 
0.9 
2.78 
71.6 
25.9 
0.9 
1.6 
18-24 . . 
48.0 
34.5 
12.1 
0.3 
1.1 
2.85 
71.8 
25.2 
0.6 
2.3 
24-30 . . 
52.2 
42.5 
8.2 
0.3 
1.2 
5.18 
81.4 
15.7 
0.6 
2.3 
30-36 . . 
74.4 
66.4 
6.5 
0.2 
1.3 
10.21 
89.2 
8.7 
0.3 
2.0 
36-42 . . 
76.1 
67.4 
7.2 
0.2 
1.3 
9.36 
88.6 
9.4 
0.3 
1.7 
of the carbonates. The soil at a depth of 
24 inches and deeper contained grains and 
needle-like crystals of gypsum. The carbo¬ 
nates in the soil above the zone of gypsum 
accumulation effervesced weakly when treated 
with cold dilute hydrochloric acid; this fact 
suggested the possibility that a high percent¬ 
age of the total carbonates was in the form 
of dolomite. The data obtained in the analy¬ 
sis of this profile were similar to those ob¬ 
tained from similar soil profiles. 
The data in Table 2 were obtained in the 
analysis of the water-soluble salts extracted 
from the soil samples of the selected profile. 
The greatest quantity of water-soluble salts 
was found in the part of the profile which 
contained the crystalline gypsum. The cal¬ 
cium and sulfate amounted to approximately 
27 and 31 milliequivalents per 100 grams in 
this horizon. The water-soluble magnesium 
increased with the increase in sulfate but the 
increase was less than that shown by the cal¬ 
cium. The milliequivalents of water-soluble 
calcium and magnesium were equal to the 
milliequivalents of sulfate in soils rich in sul¬ 
fate. This would suggest that both calcium 
and magnesium were combined with the sul¬ 
fate in this part of the profile. The lowest 
calcium-to-magnesium ratio was found in the 
zone overlying the zone of gypsum accumu¬ 
lation. 
