Exploring differences of soil quality as related to management in semiarid rangelands in the western Bophirima District, North West province, South Africa

Abstract

Differences in land-use management may result in different rangeland condition (soil, vegetation and biodiversity) and productivity. Vegetation condition in contrasting land-use management systems is well documented in semiarid rangelands, but relatively little information is available on soil quality. This study explores soil quality indicators in contrasting land-use management systems (communal, commercial and game/conservation) to compare degradation status. Soil samples collected in all land-use management systems were analysed for chemical, biochemical and microbiological properties. Soils were acidic (pH = 6.33) and nutrients deficient (average organic C [C_org] 0.37%, available P 3.04 mg kg^–1, cation exchange capacity [CEC] 2.99 cmol(+) kg^–1). Significant differences (pH, p < 0.0001; Ca²⁺, p < 0.0001; Mg²⁺, p = 0.001; Na⁺, p = 0.014; CEC, p < 0.0001; C_org, p = 0.004; dehydrogenase, p = 0.003; acid phosphatase, p = 0.001; urease, p < 0.0001) were found between the conservation and both the communal and commercial land-use management. Only few indicators of soil quality showed significant differences between the commercial and communal management. No clear gradient of soil degradation could be detected. Results recommend caution when assessing degradation across contrasting land-use management systems, and within a specific management system. Further research across a wide range of sites within management and taking into consideration spatial soil and vegetation distribution is required to understand land-use management effects on rangeland condition.

Keywords: chemical properties; enzyme activity; land-use management; microbial biomass; rangeland degradation; soil degradation

African Journal of Range & Forage Science 2009, 26(1): 27–36