Amelioration of Degraded Mine Soil for Reclamation Purposes Using an Industrial Byproduct and an Organic Waste

The South African mining industry has been the backbone of the country’s economy for much of the past century. Mining has, however, often caused the degradation of productive soils. The amendment of these soils is often very expensive and often not sustainable. The University of Pretoria in cooperation with Eskom TSI, has over the past seven years conducted a series of trials. These trials have demonstrated the feasibility of using alkaline class F fly ash (from the coal-based Lethabo power generating facility) and organic materials to ameliorate acidic and infertile soils. Various pot and on-site field trials were established to measure and monitor the dry matter production, basal cover, botanical composition and the effect of amendments on the soil chemical properties. Based on the results obtained in the pot trials, it was concluded that fly ash and fly ash/organic material mixtures improved dry matter production as well as the soil pH, extractable K, Ca, Mg and P levels. This led to the expansion of the research programme. A field trial at a surface mine in the Mpumalanga Province was established. The results from this field trial confirmed pot trial findings. All parameters measured had been influenced by the fly ash and fly ash / organic material mixtures. Fly ash and fly ash / organic mixtures had 600% and 200% higher basal cover respectively, relative to the control. With respect to soil chemical properties, soil pH of AMD impacted soils were dramatically improved by 200% by the fly ash / organic mixture. An industrial byproduct such as fly ash, either by itself, or together with organic waste, can serve as a soil ameliorant for the reclamation of surface mined land.