Reactions of Horizons in Tropical Soils

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THE reactions of a large number of samples carefully taken at different depths in the profiles of red soils which cover such large areas of south-central Africa have been determined in this laboratory. When the pH values of samples taken from a pit dug in undisturbed virgin soil are plotted against the depth, almost perfect curves are invariably obtained, there being generally a depth of from two to three feet at which the maximum acidity is obtained. This is generally coincident with the depth at which there is a tendency to form a pan both in lateritic, true red, and immature red loams, and also in the ferruginous red loams described by Marbut and Shantz. In the latter soils, indeed, the pan is associated with definite concretions of hydrated sesquioxides.

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HORNBY, A. Reactions of Horizons in Tropical Soils. Nature 129, 58 (1932) doi:10.1038/129058a0

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