INFLUENCE OF DRAINAGE REGIME ON THE CHEMISTRY AND MORPHOLOGY OF SOME MANITOBA SOILS: CLAYEY CHERNOZEMIC AND GLEYSOLIC SOILS OF THE RED RIVER PLAIN

Abstract

A number of clayey soils of the Red River-Osborne Association that developed under imperfectly to poorly drained conditions on the Red River Plain in Manitoba were studied. These soils, traditionally classified as Gleyed Chernozemic soils and Gleysolic, were characterized by morphological description, chemical and physical analyses. Most of the areas of the Red River Plain are cultivated and have had considerable improvement of surface drainage. Redox potentials, groundwater level and redox potential in the groundwater were determined at selected sites for various periods to a maximum of 2 years. Soils traditionally classified as Gleysols had shallow sola, minimal grumic features, and low chromas and mottles that would meet with present criteria; exchangeable Ca/Mg ratios were commonly near unity in the lower part of the solum. These soils were in an oxidized condition with Ept above 550 mV in the profiles; groundwater levels were below 1.4 m. Oxalate to dithionite extractable iron ratios were greater than 0.45 in the lower part of the solum on the Gleysols and those Gleyed Chernozemic soils with chromas of 2 or less with mottles. Gleyed Chernozemic soils with chromas of 2 or less with mottles would key as Gleysols using the present Canadian criteria; this would result in a change of traditional concepts. Classification of these soils according to the Canadian (taxon) and the U.S. systems are discussed. Key words: Chemical criteria, morphological criteria, water table, soil temperature, redox potential