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

• Soil inorganic C constitutes 7–9.6% of total carbon (C).
• Biogenic C varied widely (45–66%) in reclaimed minesoil.
• Small portion (7–27%).of biogenic C is labile.
• Stable carbon constitutes 72–93% of biogenic C, primarily responsible for C sequestration in reclaimed minesoil.
• Coal C contributes 47–69% of total C.

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 1500 ha−1 with average girth of 43–66 cm) along the soil profile (0–10 cm and 10–20 cm) 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.

Figure optionsDownload as PowerPoint slide