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Soil Science Society of America Journal Abstract -

Layer Charge Evaluation of Expandable Soil Clays by an Alkylammonium Method1


This article in SSSAJ

  1. Vol. 49 No. 4, p. 1054-1060
    Received: Apr 24, 1984
    Accepted: Jan 16, 1985

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  1. A. L. Senkayi,
  2. J. B. Dixon,
  3. L. R. Hossner and
  4. L. A. Kippenberger2



The interlayer charge of five reference smectites (hectorite, saponite, two montmorillonites, and a nontronite) and clay samples from strongly acidic smectitic soils of Alabama, Mississippi (Ultisols), and Texas (Alfisol) were investigated by an alkylammonium method (AAM). The total layer charge of the reference smectites based on the chemical formula ranged from 0.31 to 0.50 mol(−) per O10(OH)2. The interlayer charge density by AAM linearly increased with increasing total charge. Nontronite had the highest tetrahedral charge and exhibited the highest interlayer charge density. A qualitative distinction of soil clay samples containing low charge and high charge smectite or vermiculite was based on the d-spacings of the complexes formed by a single alkylammonium compound. Changes in relative peak intensities indicated that the low charge smectite increases whereas the high charge smectite decreases with profile depth. The low charge smectite in these soils appears to have been mostly inherited from the underlying Tertiary and Cretaceous sediments whereas the high charge smectite appears to be a weathering product of the mica present in these sediments.

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