NATURALLY OCCURRING ORGANO-CLAY COMPLEXES OF ORTHIC BLACK CHERNOZEMS

The nature and degree of organo-clay complexing in three orthic black chernozem soils were studied. Clay separated from the Ah2-horizons was fractionated into the 2-1μ (coarse), 1-0.2μ (medium), and 0.2-0.08μ (fine) fractions. Both untreated and peroxide-treated clay fractions were analyzed for clay mineral content, cation exchange capacity (C.E.C.), electron microscopic appearance, infrared spectra, carbon content, and X-ray diffraction characteristics. On the bases of experimental data it was found that the greatest degree of organo-clay complexing occurred in the 0.2-0.08μ fraction. The data indicated that complexed organic matter occupied the edges and surfaces of clay minerals. No interlamellar adsorption was detected. Infrared analysis suggested clay hydroxyl groups are involved in the adsorption of soil organic materials. © 1969.