Ecorestoration Of Waste Dump By The Establishment Of Grass-Legume Cover
Deblina Maiti, Subodh Kumar Maiti
Index Terms: Ecorestoration, grass-legume mixture, waste dump, topsoil, coir-mat
Abstract: This study investigated the usefulness of grass-legume mixture as an initial cover species to initiate ecorestoration process on a hazardous waste dump, produced by the wastes from an integrated sponge iron plant. During production of sponge iron huge amount of solid wastes are generated, which is considered as hazardous material, with alkaline pH; composed of dolochar, coal fines, slag and fly ash; posing serious threat to the surroundings. The area occupied by waste dump was approximately 5 ha and surface area; 3.4 ha was located inside forests. The average dump height varied between 40-50m with a steep slope greater than 70o. Before ecorestoration work, dump was blanketed with a thick layer of topsoil (1-1.2 m) and slope was covered by coir-mat followed by sowing of grass-legume seed mixture before monsoon onset. Dominant grass species was Pennisetum pedicellatum; drought tolerant and quick growing; while legume seeds consisted of Stylosanthes hamata, Sesbania sesban, and Crotalaria juncea. S. hamata is perennial, whereas C. juncea, S. sesban completes their life cycle within 5-6 months and their dead aerial parts contributed nitrogen rich litter to the soil. Dry subterranean parts of the annual grass P. pedicellatum acts as mulch. In a whole, it has been observed that grass-legume growth initiated nutrient cycling in hostile conditions, which was corroborated by analyzing rhizospheric soil samples of grass-legume cover at an interval of six-seven months. Study concluded that hazardous waste dump with steep slopes can be restored by application of grass-legume mixture, topsoiling and coir matting that leads to a sustainable plant soil interaction.
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