Review of soil form and wetness indicators for wetland delineation in South Africa

Authors

  • JH van der Waals 1. Terra Soil Science, 686 Cicely Street, Garsfontein, Pretoria 0081, South Africa; 2. RealIPM SA (Pty) Ltd, PO Box 130, Grabouw 7160, South Africa https://orcid.org/0009-0007-7854-5632
  • DG Paterson Agricultural Research Council (ARC) – Natural Resources and Engineering (NRE), 600 Belvedere Street, Arcadia, Pretoria 0083, South Africa
  • A Grundling 1. Agricultural Research Council (ARC) – Natural Resources and Engineering (NRE), 600 Belvedere Street, Arcadia, Pretoria 0083, South Africa; 2. Applied Behavioural Ecology and Ecosystem Research Unit, UNISA, Pretoria, South Africa; 3. Centre for Environmental Management, University of the Free State, Bloemfontein, South Africa
  • DP Turner Formerly Agricultural Research Council (ARC) – Institute for Soil, Climate and Water (ISCW), 600 Belvedere Street, Arcadia, Pretoria 0083, South Africa
  • CW van Huyssteen 1. University of the Free State, PO Box 339, Bloemfontein 9300, South Africa; 2. RealIPM SA (Pty) Ltd, PO Box 130, Grabouw 7160, South Africa
  • PS Rossouw Rossouw and Associates Soil and Water Science (Pty) Ltd, Cyferfontein, Modimolle 0150, South Africa

DOI:

https://doi.org/10.17159/wsa/2024.v50.i2.4087

Keywords:

South African soil classification system, redox morphology, Fe and Mn minerals, wetland soil indicators, wetland delineation

Abstract

Wetland delineation in South Africa incorporates soil form and soil wetness indicators, requiring formal soil classification and description of soil redox morphology. The current wetland definition used administratively in South Africa focuses on saturated (hydric) soil signatures within plant root zones. Saturated soil horizons deeper than plant root zones fall outside the 50 cm criterion in the local approach as well as the accepted zone in USA literature. The field of hydropedology accommodates the classification of the various hydrologically active horizons and provides a tool for the handling of horizons with ephemeral wetness. This approach has been variably accepted by mandated authorities in South Africa. The South African soil classification system has evolved through three editions over the past 50 years while retaining the same redox morphology understanding. However, despite the concepts and context of redox morphology having been thoroughly technically adopted by soil scientists, this is not the case within the wetland research and management environment. This especially because the classification system is structured differently from other international systems, and the South African landscape is geologically ancient with mature soils, introducing challenges to resource assessment specialists who rely on international norms and approaches for wetland assessment. This paper reviews the various components of soil classification and redox morphology based on Fe and Mn minerals within the context of the South African soil classification system, the field of hydropedology and wetland delineation indicators. We provide a qualitative correlation between the various diagnostic horizons and materials in the system and their related redox morphology contexts that are relevant to wetland assessment, delineation, and protection in South Africa. This paper therefore aims to serve as a reference point for the description and correlation of various soil hydrological parameters used in formal assessments.

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Published

2024-04-30

How to Cite

JH van der Waals, DG Paterson, A Grundling, DP Turner, CW van Huyssteen, & PS Rossouw. (2024). Review of soil form and wetness indicators for wetland delineation in South Africa. Water SA, 50(2 April). https://doi.org/10.17159/wsa/2024.v50.i2.4087