Assessment of soil quality across differently aged, naturally recovered old crop fields and natural sites in a Grassland biome

Abstract Cropland abandonment for natural recovery has increase globally over the las few decades. Changing land-use practices in South Africa, has led to an increased rate of cropland abandonment. The rate and magnitude of soil quality recovery following abandonment varies from location to location. Several soil quality studies have been conducted in the Eastern Cape Province of South Africa, mainly focusing on the impact of different cropping strategies on soil quality or the effect of different grazing practices on soil quality. Only a few studies on the effect of cropland abandonment and soil quality have been performed. We, therefore, aimed to assess the change in soil quality of differently aged, recovering old crop fields compared to the surrounding natural veld. The study site is located in the Winterberg Mountains of the Eastern Cape, South Africa. Soil characteristics, including soil water-holding capacity, density, pH, total dissolved solids and electrical conductivity, C %, N %, C stock, N stock, as well as sand, silt clay composition was assessed for three recovering old crop fields. Samples from the surrounding natural habitat were also included for comparison. Significant positive change in soil water-holding capacity (WHC), C %, N %, C stock and N stock were observed with increased age since abandonment. It is clear from our results that soil recovery is taking place, with the older former crop field most closely resembling the natural habitat. It will, however, still take a significant amount of time for total recovery to be achieved. Continuous monitoring of old crop fields in agricultural, as well as, formally protected areas is needed to fully understand the long-term effects of cropping on soil quality in this region. Significance • Cropland abandonment is a global occurrence, with old croplands allowed to recover to a natural state. • The effect of old cropland abandonment on soil quality in the Eastern Cape Province of South Africa is not well studied. • No significant differences in pH and electrical conductivity was observed between differently aged old crop fields, but an increase in water-holding capacity, % soil N and % soil C was observed with increase old crop field abandonment age. • These results contribute to the limiting amount of data on soil physical characteristics natural recovery of old crop fields in the Eastern Cape of South Africa