Technosol made from coal waste as a strategy to plant growth and environmental control

Abstract

Coal waste disposal areas demand proper rehabilitation activities because several environmental impacts are related to them, such as acid mine drainage, loss of biohabitats, water pollution, and soil degradation. The most common strategy is to cover them with an impermeable layer followed by a new soil layer as soon as possible, while maximizing plant growth and avoiding water and wind erosion. This study examines the possibility of transforming coal waste itself into a substrate for plant growth, namely technosol, assuming its own use for progressive rehabilitation and revegetation of waste deposits. The coal waste is amended with other residues in an integrated waste management approach: rice husk ash, steel slag, and sewage sludge to adjust physical structure, pH, and nutrient availability, respectively. The raw material composition, fertility, metals bioavailability, plant growth, and nutrients in plant tissue are analyzed after successive growth of lopsided oats (Avena strigosa) and maize (Zea mays). The results show that coal waste allows a fertile plant substrate after being amended in accordance to experimental conditions. The soil metal concentration is found to fall within the limits of natural variation for soils in the study area and nutrients in plant tissue are found to be consistent with lopsided oats and maize standards. The proposed waste mixture results in a technosol capable of adequately promoting plant growth, that is, it is a potential resource to accelerate revegetation and natural succession in coal waste disposal areas.