CATION EXCHANGE AND ASSOCIATED PROPERTIES OF SOME SOILS FROM VANCOUVER ISLAND, BRITISH COLUMBIA

Abstract

Studies of the cation exchange properties of the soils of Vancouver Island, British Columbia showed that, in general, the soils had high base saturation even though the precipitation was high. There was no consistent relation between the corrected lime potential values for the soils and the annual precipitation. The pH-dependent CEC values of the soils were highly correlated with organic matter and oxalate-extractable Al but poorer correlations were obtained with the clay content and oxalate-extractable Fe. The correlation between pH-dependent CEC and citrate-dithionite-extractable Fe was not significant. Complexes of Al with organic matter appeared to be the main source of the pH-dependent CEC in the soils.Soils from the drier southeastern part of the Island with fragipans had as low or lower corrected lime potential values in the upper part of the profile than did soils from the more humid and more densely forested parts of the Island. Although oxalate-extractable Al was accumulated in the upper solum of soils with fragipans there was no pronounced enrichment of either oxalate- or citrate-dithionite-extractable Fe. The corrected lime potential pattern and the free oxide distribution of the soils with fragipans differed from the soils without fragipans.