Original Articles

Improved criteria for classifying hydric soils in South Africa

Published in: South African Journal of Plant and Soil
Volume 13, issue 3, 1996 , pages: 67–73
DOI: 10.1080/02571862.1996.10634378
Author(s): D.C. KotzeDepartment of Grassland Science, Republic of South Africa, J.R. KlugDepartment of Grassland Science, Republic of South Africa, J.C. HughesDepartment of Agronomy, Republic of South Africa, C.M. Breen, Republic of South Africa

Abstract

There is an increasing awareness of the ecological and agricultural importance of hydric (wetland) soils. Because of the scarcity of information in South Africa, this study aimed to critically examine systems currently being applied to the hydric soils of South Africa, recommend the best criteria to be used from a management point of view, and suggest future research. Soil taxonomy (Soil Survey Staff, 1975) was found to be superior to the South African soil classification system for describing hydric soils, primarily because it accounts for depth of waterlogging. Nevertheless, Soil taxonomy does not account adequately for degree of wetness, with some series including a wide range of water regimes. A review of soil morphology/water-regime studies revealed that along the continuum from temporarily wet to permanently wet areas: matrix chroma decreases; the most intensively mottled zone becomes progressively shallower; mottle abundance increases then decreases; and soil organic matter increases. Based on these trends and observations of wetlands in KwaZulu-Natal, a three-class water-regime classification system with distinguishing field characteristics was developed. Provisionally, this system could be used in combination with Soil taxonomy or the South African Soil Classification system for enhancing the description of hydric soils in South Africa. However, this three-class system has not been adequately tested and it is strongly recommended that local studies be undertaken to improve the capacity for clearly describing hydric soils.

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