THE ACCUMULATION OF SOIL ORGANIC MATTER AND ITS CARBON ISOTOPE CONTENT IN A CHRONOSEQUENCE OF SOILS DEVELOPED ON AEOLIAN SAND IN NEW ZEALAND |
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| Authors: | K M GOH T A RAFTER J D STOUT T W WALKER |
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| Institution: | (Department of Soil Science, Lincoln College, Canterbury, New Zealand) |
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| Abstract: | Soil organic matter was extracted by a mixture of O.IM Na4P2O: O.IM NaOH from a chronosequence of weakly weathered soils developed on aeolian sand, and fractionated into humin (non-extractable), humic acid, and fulvic acid. The mass of total organic carbon in the profiles, the 14C content and the 13C/12C ratios were also determined. The weight of total carbon increased rapidly at first and then gradually without attaining a steady state. This trend was also shown by the humin and fulvic acid fractions, but the humic acid fraction appeared to have reached a maximum after about 3000 years. The order of total weights of the organic fractions was humin > fulvic acid > humic acid. The evidence suggests that the proportions of the humic fractions formed by decomposition are related to soil differences but not to vegetation. The greater part of the plant material found in the soils appears in the humin and fulvic acid fractions. |
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