Abstract

Clay colloids are the most important fraction responsible. for the base exchange phenomenon in soils. Donahue (1958) considers the cation exchange capacity to be the single index of fertility. Therefore, the more clayey the soil, the more is its cation exchange capacity and hence the chances of its being fertile are greater. Hocking (1948) reported that clay minerals present even in the coarser fractions of the soil also contribute to the cation exchange phenomenon. The individual contents of silica, alumina, iron oxide, potash and magnesia in the clay are indicative of the dominant clay minerals (Grim 1953). The ratio between silica, alumina and iron oxide has widely been used in assessing the nature of clay minerals and process of soil formation. In the present investigation, the clay samples fractionated from alkali and adjoining soil profile samples have been analysed for their chemical composition with a view to studying the depthwise distribution of clay minerals content in the profiles.

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