Importance of carbon fractionation for the estimation of carbon sequestration in reclaimed coalmine soils—A case study from Jharia coalfields, Jharkhand, India

Abstract

Reclaimed mine soils (RMS) provide an excellent opportunity to sequester Carbon (C) both in mine soils and vegetation, as RMS initially lack biogenic C. Soil C in RMS consists of inorganic Carbon (IC), biogenic Carbon (recent C) and geogenic Carbon (coal C). In Indian mining conditions, estimation of C sequestration of RMS sites are difficult due to presence of substantial amount of coal C contributed during mining and reclamation activities, which overestimates the values of C sequestration. Conventional procedures for estimation of soil organic carbon (SOC) cannot distinguish between biogenic and coal C in the RMS. The objective of this study was to find out relative distribution of inorganic, biogenic and coal C fractions in a 10 year old RMS (tree density 1500ha−1 with average girth of 43–66cm) along the soil profile (0–10cm and 10–20cm) by chemical fractionation methods and compare with unreclaimed site. Inorganic C constitutes 7–10% and 11–19% of total soil carbon (TSC) in RMS site and unreclaimed site, whereas biogenic C constituted 45–66% and 21–25% of TSC in RMS and unreclaimed site, respectively. Both labile and stable C fractions were found higher in RMS site than unreclaimed site. Coal C contributed higher in unreclaimed site (68–55%) than the RMS site (47–24%). The study concluded that estimation of IC, biogenic C and coal C is essential for estimation of C sequestration potential in RMS for the dry tropical climate.