The solubility of aluminum-organic matter and its implication in plant uptake of aluminum
1986
HARGROVE, W. L.
This experiment was prompted by the observation that plant uptake of Al and depression of growth and yield of plants occur at near neutral soil pH in soils of high organic matter content. The objective was to demonstrate that Al-organic matter complexes may be solubilized in the pH range of 5 to 7 and thereby become available to plant roots and account for “Al toxicity” effects at pH values near neutrality. Suspensions of Al-muck were adjusted to various pH levels and filtered. Optical density was measured on the filtered solutions, and then the solutions were treated with hydrogen peroxide to oxidize the solubilized organic matter. The Al concentration was measured after oxidation. Results demonstrate that Al-organic matter may be solubilized in the pH range of 5 to 7 and may therefore be subject to plant uptake. This may be invoked as a likely mechanism explaining Al uptake and plant growth depression at near neutral soil pH values.
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