THE PEDOGENETIC ORIGIN AND CHARACTERISTICS OF ORGANIC MATTER OF SOLOD SOILS

The pedogenetic origin of dark subsurface horizons of a Dark Brown Solod and Solod-like soil from the prairie region of Saskatchewan was studied. The soils had thick, strongly acidic A horizons, dark-colored B horizons and saline C horizons. Standard soil analyses, humus fractionation and measurement of the plant opal phytolith content of the 20–50 μm fraction were done. The dark B horizons contained 1.5 to 2.0 times more organic carbon than the adjacent horizons. The phytolith content decreased regularly with depth, indicating that the dark horizons were not buried surfaces. Consistent with generally accepted theories, they appeared to have formed by the translocation of humic materials in a high sodium environment. The illuvial humus of the B horizon was predominantly humic acid with a high level of aromaticity. Leachates of sodium-saturated A horizon soil contained organic matter with a ratio of humic:fulvic acids and spectral properties similar to the organic matter of the illuvial B horizons.