Short Communications/Kort Mededelings

The base status criterion in South African soil classification

Published in: South African Journal of Plant and Soil
Volume 11, issue 3, 1994 , pages: 149–151
DOI: 10.1080/02571862.1994.10634315
Author(s): M.V. FeyDepartment of Agronomy, Republic of South Africa, M.J. Donkin, Republic of South Africa


Evidence is considered which indicates that the sum of extractable bases and acidity, termed the effective cation exchange capacity (ECEC), is a more reliable criterion than the S-value (sum of exchangeable bases only) for differentiating soils in terms of the climatic conditions associated with their formation. ECEC correlated better with an index of water balance calculated from long-term climate data at 33 selected sites in the Natal midlands. It can be expected to exhibit greater constancy both seasonally and after chemical amendment, and it also conforms better with international practice. Superior prediction of climate by ECEC is not unexpected because ECEC integrates both the degree of leaching and the mineralogical stage of weathering. In strongly leached, acidic soils, base status alone (S-value) is too depleted to serve as a sensitive and reliable discriminant of the climatic conditions at different sites.

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