Magnetic susceptibility of soils in different slope positions in Saskatchewan, Canada

Abstract

The magnetic susceptibility ( χ) of soils varies with the slope position due to some factors, such as texture and drainage class. This study attempts to link χ to soil profile characteristics [soil horizon type, organic and inorganic C, sand and oxalate (Feo) and dithionite (Fed) extractable iron] measured on soil cores collected from the three uncultivated soil catenas in Saskatchewan. The parent material at all sites consisted of medium-textured hummocky glacial till. The Waitville catena (Gray Luvisol) was developed under trees, the Weyburn catena (Dark Brown Chernozem) under grass, and the Oxbow catena (Black Chernozem) had trees on the lower slope and grass in the center of the depression and on the upper and middle slopes. In all the three catenas, a downslope decrease in χ was correlated with increasing Feo/Fed ratios and decreasing sand content. Lower slope gleyed profiles in the two Chernozemic catenas had high Feo/Fed ratios and low χ. The impact of gleying was most evident in the solum and χ tended to increase in the C-horizons of these profiles. The χ of the sand and silt fractions was positively correlated with that of the bulk soil, whereas, the χ of the clay fraction did not vary with the χ of the bulk soil. Stable sand-sized magnetite grains are believed to be rare in these soils.