A STUDY OF THE CLAY-HUMUS COMPLEXES OF A CHERNOZEMIC AND A PODZOL SOIL

Abstract

The clay mineralogy of the humate and KCl floc fractions separated from a Dark Brown Chernozemic and a Podzol soil by the Tyulin method was studied. The predominant minerals, montmorillonite and illite, and small amounts of kaolinite appeared in all fractions. The smaller-sized and less well-crystallized clays were concentrated in the humate fractions. In general, the podzol colloids contained more "free" iron and aluminium than the chernozem colloids, and the humate fractions in both contained more than the KCl floc fractions. From studies of the organic matter after treatment with dithionite and EDTA, it appeared that amino groups were involved in the union between organic matter and the inorganic constituents.