Soil Quality in Rehabilitated Coal Mining Areas

In arid and semiarid environments, the sustainability of rehabilitation actions in degraded areas is a matter of concern. It has not been extensively researched. In a Spanish coal mining area, new soils to support vegetation were created (Technosols) using mine spoils and different organic wastes. Eight years after the establishment of rehabilitation measures, the quality of the works was assessed. Soil properties (organic matter, microbial biomass, structural stability and porosity) were evaluated as quality indicators. Thermogravimetric analysis differentiated between organic-C and other mineral-C sources. The degree of aggregation and the presence of interconnected pores and organic matter with different degrees of decomposition were identified by micromorphological techniques. Microbial biomass and water-stable aggregates satisfactorily traced the early pedogenesis of mine spoils, resulting in good indicators of the quality of new Technosols. Substrates prepared with sludges promoted soil development better than those created using pig slurries, primarily by favoring a higher porosity and organic matter content. Despite that, both treatments demonstrated, after 8 years, their ability to support the ecosystem services of biomass production, carbon sequestration, and organic matter recycling they were planned for, therefore ensuring their sustainability.