Comparative soil restoration potential of exotic and native woody plantations on coal mine spoil in a dry tropical environment of India: A case‐study

Abstract

AbstractOverburden excavated during opencast mining has poor soil properties due to non‐salvage and inversion of soil profiles. The soil properties of such overburden are often improved by biological reclamation techniques such as planting suitable plant species; however, the performance of species varies from site‐to‐site. Therefore, this article aims to evaluate the effects of woody plantations on coal mine spoil's physicochemical and biological properties. We synthesised the available data from previous studies conducted on 5‐year‐old plantations in the Singrauli Coalfields of India. These plantations have monocultures of eight species, in which four were exotic (Acacia auriculiformis, Casuarina equisetifolia, Cassia siamea and Grevillea pteridifolia) and four were native species (Albizia lebbeck, Albizia procera, Dendrocalamus strictus and Tectona grandis). We compared the soil properties under exotic and native species plantations to evaluate the effect of species and origin. The Wilcoxon's test showed that the clay content (p = 0.000), ammonium‐nitrogen (p = 0.002), phosphate‐phosphorus (p = 0.000) and microbial biomass nutrients (C, N and P; p = 0.000) were significantly higher under native plantations than the exotic plantations. Further, we observed a significant positive correlation (r = 0.86, p < 0.001) between soil organic carbon and microbial biomass carbon for native species. We also found that microbial biomass nutrients are negatively associated with nitrification rates and positively associated with nitrogen mineralisation rates. Overall, our study suggested that exotic species plantations are not as effective as native species in mine spoil rehabilitation. Thus, native species plantations should be promoted while restoring degraded coal mine habitats in a dry tropical environment.