Geology and groundwater regions to quantify primary salinity, sodicity and alkalinity in South African soils

Soils in the Richtersveld Cultural and Botanical Landscape exhibit among the highest primary salinity, sodicity, and alkalinity in South Africa. Research reveals that soils from the Whitehill Formation (Ecca Group) are notably saline (median EC = 2720 mS m⁻¹) and sodic (median ESP = 79.8), while those in the Richtersveld groundwater region show extreme sodicity (median ESP > 20). Alkaline soils (median pH > 8.5) dominate the Richtersveld Subprovince, Eendoorn granite geological unit, and specific groundwater regions like the Richtersveld, Ghaap Plateau, and Western Kalahari. Highest salinity correlates with arid western areas of the Northern and Western Cape, particularly in closed basins and intermontane zones. This study quantifies primary soil conditions using geological units and groundwater regions, providing critical baseline data for understanding natural salinity, sodicity, and alkalinity in South African soils.

Nell, J. P., & van Huyssteen, C. W. (2014). Geology and groundwater regions to quantify primary salinity, sodicity and alkalinity in South African soils. South African Journal of Plant and Soil, 31(3), 127–135. https://doi.org/10.1080/02571862.2014.921940