抄録
The cation exchange capacity (CEC) derived from octahedral layer charges (OLC) (CEC_<OLC>), the CEC derived from tetrahedral layer charges (TLC) (CEC_<TLC>), and the amount of Al as a hydroxy-Al polymer in interlayer sites (Al_<HIM>) were determined for natural soil clays fractionated from acidic forest soils (Dystrudepts) developed from sandstone and shale in Kinki-district of Japan. The CEC_<OLC>, determined by the reduced amount of CEC after Li-saturation and heating to 250℃ (Greene-Kelly test), was not correlated with Al_<HIM>, estimated from the amount of Al extracted with hot sodium citrate. In contrast, an approximate index value of CEC_<TLC>, represented by the residual CEC at pH 5.0 after subtracting the CEC_<OLC> was correlated negatively with Al_<HIM>, suggesting that CEC_<TLC> is largely responsible for the stabilization of hydroxy-Al polymers in 2:1 phyllosilicates.