CATION EXCHANGE CAPACITIES AND SURFACE AREAS OF HUMIC GLEYSOLIC Ap HORIZONS FROM SOUTHWESTERN ONTARIO

Abstract

Thirty-four samples from the Ap horizons of heavy-textured Orthic Humic Gleysols (Typic Haplaquolls) were sampled in southwestern Ontario. Surface areas of the soils ranged from 79–223 m2/g and multiple regression analysis indicated that the surface area of the clay fractions was 207 m2/g and that of the organic matter 805 m2/g. Approximately 74% of the variability in cation exchange capacity could be attributed to their clay and organic C contents at pH 4 and about 86% at pH 8. A value of 181 meq/100 g was calculated as the cation exchange capacity of organic matter at pH 4 and of 316 meq/100 g at pH 8. Mean cation exchange capacities at pH 4 were 20.3 meq/100 g and 31.6 meq/100 g at pH 8.