DISTRIBUTION OF IRON, CLAY AND EXTRACTABLE IRON AND ALUMINUM IN SOME SASKATCHEWAN SOILS

Abstract

The variability of oxalate- and dithionite-extractable iron and aluminum throughout the soil profile and their relationship to total iron and clay contents were investigated for soils representative of the Chernozemic, Solonetzic, Luvisolic and Gleysolic soil orders of Saskatchewan. These distributions and relationships are similar for Chernozemic, Solonetzic and Luvisolic soils. They indicate comigration of iron and clay. Oxalate-extractable iron is low and relatively constant throughout the depth of the soil. Dithionite-extractable iron is somewhat higher and always exhibits a maximum in the B horizons. In all but the Luvisolic soils, the ratios of dithionite-extractable iron to clay are significantly higher in the Ae horizon than in the B horizons. This reflects a higher content of dithionite-extractable iron in the coarse clay fraction than in the fine clay fraction of these soils. Gleysolic soils show different relationships in some respects; oxalate-extractable iron equals that extracted by dithionite in the Ae horizon, reflecting the effect of reducing conditions on iron extractability.