Rehabilitation of arid rangelands: Intensifying water pulses from low-intensity winter rainfall

The improvement of water availability for plant growth is of major concern for successful rehabilitation in degraded (semi)arid rangelands. This study investigates how rehabilitation techniques affected soil-wetting and soil water storage after a typical low-intensity winter rainfall event in the Succulent Karoo, South Africa.We compared the impact of six rehabilitation treatments (brushpacks, fertilizer, dung, hessian, microcatchments and planting, each applied with and without livestock exclusion) on soil water status after a typical winter rainfall event of 5.2 mm, one year after treatment implementation. We also recorded the impacts of the treatments on soil infiltrability and surface compaction.Treatment induced differences in soil infiltrability and compaction did not affect soil-wetting during the rainfall event since the rainfall rate was too low for the production of runoff. Brushpacks and planting resulted in accumulation of water in the soils below these treatments, probably by capturing wind-driven water droplets. Soil water retention was prolonged by all treatments that shaded the soil (brushpacks, dung, hessian, planting). One year of livestock exclusion did not affect any of the measured parameters significantly.This study highlights mechanisms through which rehabilitation measures may achieve an intensification of water pulses for plant growth under conditions of low-intensity winter rainfall.

Research highlights
► Low-intensity winter rainfall creates specific conditions for rehabilitation.
► Soil infiltrability plays a minor role for soil-wetting during low-intensity rains.
► Water accumulation by capturing wind-driven droplets deserves further investigation.
► Covering the soil surface retards evaporative loss of soil water.