Grassland productivity of communal rangelands is limited by land degradation, which leads to nutrient depletion, soil fertility decline and overall soil quality. However, little is known as to what the soil quality threshold is for different degradation intensities. To address this, we selected a 0.05 m surface soil layer of a communal rangeland site in Drakensburg, South Africa, exhibiting a degradation gradient varying from heavily degraded (0–5%, grass aerial cover), moderately degraded (25–50%) and non-degraded (75–100%) grasslands, to evaluate the effects of land degradation on soil aggregate stability, compaction, bulk density and texture. Results indicate that land degradation decreased soil aggregate stability by 47%, increased soil compaction by 42% and increased soil bulk density by 12%, and these were accompanied by a pattern of lower sand and almost two times greater clay content in heavily degraded grassland compared with non-degraded grassland. Ultimately, this decline in the soil quality of the communal rangeland has serious implications for the ecosystem services and functions it provides, such as storing water, carbon sequestration and nutrient cycling. We recommend the protection and improvement of grass vegetation because of its dense sward characteristics, which intercept raindrop energy, slow surface runoff and increase the structural stability of the soil to minimize and prevent degradation in rangelands.
Part of the book: Land Degradation and Desertification