Quantifying Soil Quality in Dryland Regions as A Key Step in Phosphate Mining Restoration

Mining is crucial in driving economic development but entails extensive environmental damage, such as soil degradation and water and air pollution. Mining activity impacts the soil quality, often making it unable to support ecosystem function and structure and reducing its ecological resilience. Soil degradation reduces physical, chemical, and biological (PBC) soil properties. The current study aims to apply the soil quality index (SQI) to quantify soil restoration success in an open-pit phosphate mine in Israel’s hyper-arid environment. In this regard, we evaluated an ecological restoration practice that includes topsoil refilling compared to the adjacent undisturbed natural system. We used transformed and standardized scorings of 11 PBC soil properties that were further statistically integrated into overall SQI values. Our results revealed significant differences between the restoration practice areas and the nearby natural areas, with a higher soil quality value in the latter. It is proposed that the topsoil restoration method is mainly affected by soil biological indicators, such as soil organic matter, soil proteins, and polysaccharides related to biocrust development, and, to a lesser extent, by physical properties (primarily infiltration rate, followed by available water content). The former properties encourage the biocrust establishment, which is essential for soil surface stabilization. This, in turn, affects the water infiltration, nutrient availability, and erosion rates. The chemical indicators showed no significant differences between most sites for the overall soil quality. In conclusion, our results reflect a slow recovery of the SQI in the restored sites, demonstrating that achieving the quality of the natural areas requires a long-term recovery process. Moreover, the physio-biological indicators were more suitable for reliably estimating mining restoration practices in dryland areas. Our approach could have broader implications for evaluating the ecological restoration success in hyper-arid environments.