Physicochemical characteristics of communal rangeland soils along two defined toposequences in the Eastern Cape, South Africa

Abstract

To proffer a sustainable solution to rangeland degradation, an understanding of the innate soil properties is vital. This study investigated the relative association of surface (0–20 cm) soil physicochemical properties, viz. electrical conductivity, cation exchange capacity (CEC), soil organic carbon, available phosphorus, particle size composition, soil aggregate stability and microbial respiration, along a toposequence in two vegetation types. The study sites and vegetation types were Magwiji (Lesotho Highland Basalt Grassland) and Upper Mnxe (Tsomo Grassland). In each site, we identified three experimental units along toposequence delineation, classified as crest, midslope and valley bottom. Vegetation type significantly (p < 0.05) affected sand fraction, aggregate stability under fast wetting, and mechanical disaggregation and CEC. Toposequence delineation significantly (p < 0.05) affected fast wetting, slow wetting, mechanical disaggregation, microbial respiration and CEC. There was significant variation and relationship between vegetation types, toposequence delineation and soil properties. The results suggest that toposequence delineation more than vegetation type influences soil property rangelands; therefore, in determining site-specific management techniques for communal rangelands it is important to consider the direction and magnitude of these relationships.