MINERAL DISTRIBUTION AND WEATHERING IN CHERNOZEMIC AND LUVISOLIC SOILS FROM CENTRAL SASKATCHEWAN

Abstract

The quartz, feldspar and mica contents of various fractions from soils developed from both glacial till and lacustrine deposits are compared. Similar mineral compositions are noted for both types of deposits. Using quartz as a resistant index mineral, the degree of weathering of micas, K-feldspars, Na-feldspars, Ca-feldspars, dolomite and calcite are evaluated for an Orthic Black Chernozemic soil and an Orthic Gray Luvisol. The latter soil has been more severely weathered than the Chernozemic soil, showing approximately double the losses of mineral components. Mineral losses from the entire solum of the Gray Luvisol include 40% of the Ca-feldspars, 22% of the Na-feldspars, and 17% of the K-feldspars. Although there is evidence of mica loss within upper horizons of both profiles, the K-depletion in upper layers is balanced by mica increases (K sorption) in lower solum horizons. Possible mechansims of K sorption and desorption among different size fractions are proposed.