A study on the soils containing amorphous materials in the island of Hawaii

Houng, Kun-Huang
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Four soils derived from volcanic ash deposited on the slopes of Mauna Kea were collected and examined physico-chemically and mineralogically. A Reddish Brown (Waikaloa), two Reddish Prairie (Mahoelua and Waikii), and a Latosolic Brown Forest soil (Hanipoe) were included in this study. The degree of weathering of the soil material increased in the order, Waikaloa < Mahoelua < Waikii <Hanipoe and decreased with depth for each profile. Soil properties were found to vary with the degree of weathering . The following relations among these soils were found: 1. Organic carbon content increased in the order given above. It decreased with depth in the first three soils, but varied irregularly with depth in the Hanipoe soil. Nitrogen was highly correlated with carbon in the four soils. 2. Within a given soil profile, phosphorus was highly correlated with carbon. The soil phosphorus was found to be mainly in the inorganic form. The phosphorus content of the surface soils was related to the rate of organic matter production, while the carbon content was related to the ratio of the rate of production and decomposition of organic matter. Based on these assumptions, it was shown that the organic matter production was lowest in the Waikaloa soil, highest in the Mahoelua, and decreased in the order, Mahoelua, Waikii, and Hanipoe. Decomposition rates decreased in the order, Waika10a, Mahoelua, Waikii, and Hanipoe soils. 3. There was a significant correlation between moisture equivalent and 15 atmosphere percentage of the Waikaloa, M3.hoelua, and Waikii soils. No such correlatlon was found in the Hanipoe soil. 4. Cation exchange capacities of these soils were shown to be highly dependent on the concentration ratio of base and hydrogen ions of the leaching solution. Comparison of exchange curves of some synthetic silica, aluminosilicate and alumina gels to those of soils and clays suggested that (a) the functional groups which gave inflection points near pH 8 were due to surface silanol groups; (b) functional groups which were effective in cation exchange in the acid range were probably due to internal charges which were attributable to tetrahedrally coordinated aluminum atom's; and (c) silanol groups of discrete silica units were present in these soils. 5. It was shown that halloysite content decreased with increasing degree of weathering. The non-crystalline components increased inversely with halloysite content. 6. A scheme for secondary aluminosilicate mineral formation from volcanic ash is given below.
Thesis--University of Hawaii, 1964.
Bibliography: leaves 176-187.
xiii, 187 leaves ill. (part mounted), tables
Soils -- Composition, Soil formation, Soils -- Hawaii -- Hawaii Island
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