Advances in pedology in South Africa

Abstract

The ability of soil to serve as a unique buffer of water, organic carbon, nutrients, pH, redox and temperature is recognised in environmental research. A detailed study on hardpan carbonate and dorbank horizons in the commonly occurring ‘heuweltjies’ of the arid Namaqualand coastal region revealed a ‘sepiolitic’ hardpan carbonate centre through ‘sepiolitic’ / ‘petrosepiolitic’ (hardened) to the dorbank horizon on the edges. Footprints of ferrolysis manifests in various properties of duplex and plinthic soils of the semi-arid eastern Free State as (1) acidity, (2) colour, (3) Fe-Mn, (4) mottles and concretions, (5) CEC and (6) abrupt textural differentiation. Soils with melanic A horizons cover 2% of South Africa and are confined to regions with annual rainfall between 550 and 800 mm (aridity index of 0.2–0.5). The understanding of soil formation is applied to divide a land type into soilscapes with a more homogeneous soil distribution pattern. The quantification of the water regime of South African soils showed that ‘freely drained’ soils may have significant periods of drainable water.