Quantitative Evaluation of Pedogenic Changes in Boralfs (Gray Luvisols) of East Central Saskatchewan

Abstract

AbstractZirconium oxide/quartz ratios for the soil horizons of three Boralfs (Gray Luvisols) indicated that two of the soils were developed from sufficiently uniform deposits to permit quantitative evaluations of changes resulting from soil formation. A “pedogenic index” based upon total quartz content of horizons allowed the expression, as a percentage, of soil constituents present in relation to original contents in either total horizons or in component soil separates within them. The index, based upon the total quartz content of each horizon, provides values that overcome errors resulting from changes in particle size distribution of quartz such as occurs in Boralfs or other soils where significant physical breakdown of coarse to finer fractions has occurred. The index shows that approximately one‐third of the original sand in the E horizons has been physically weathered to finer sizes, dominantly to coarse silt size, but also down to clay size. Elemental analyses indicate that the Na‐ and K‐bearing minerals are more resistant than the Ca‐ and Mg‐bearing minerals, and that weathering has occurred in all size fractions. As a consequence, Ca and Mg, and to a lesser extent, Na and K, undergo greater net losses from the solum than do Si, Al, and Fe. Redistribution of the latter three elements within the sola is directly associated with the translocation of clay. Physical breakdown and lessivage are the major processes in all three soils, but chemical weathering and leaching losses are also important. Preferential translocation of fine clay (<0.2 µm) and the weathering of coarse clay (2‐0.2 µm) to fine clay size in both E and Bt horizons is substantiated.