Distribution of soil organic carbon and glomalin related soil protein in reclaimed coal mine-land chronosequence under tropical condition

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The revegetation on mine spoiled lands has potential to improve the status of reclaimed mine-soil quality. However, to date the temporal dynamics of labile and stable fractions of soil organic carbon (SOC) and glomalin related soil protein (GRSP) have not been satisfactorily demonstrated. We investigated SOC and GRSP fractions including labile particulate OC (POC) and easily extractable GRSP (EE-GRSP) and stable non-particulate OC (NPOC) and difficulty extractable GRSP (DE-GRSP) along with other important soil properties in six reclaimed mine lands chronosequence (1 to 26 years old) and a reference forest site in Raniganj Coalfield, India. Our results demonstrated that the accumulation of SOC and GRSP significantly increased with increasing age of the sites, with greater extent of increment after 26 years were seen in labile POC (6.6×) and EE-GRSP (11.5×) compared to stable NPOC (1.8×) and DE-GRSP (6.2×). The higher contribution of GRSP-C in NPOC compared to TOC across the sites, indicate the proximate role of GRSP in accumulation and stabilization of SOC during the pedogenesis. The multivariate analysis revealed strong association among arbuscular mycorrhizal fungi (AMF) spore density, microbial biomass carbon, SOCs and GRSPs, suggesting the factors involved in SOC accumulation likely contributed to AMF proliferation and GRSP enrichment during the reclamation process. Moreover, strong correlation of GRSP and SOC with soil's bulk density, pH, total N and C/N ratio, suggest increasing GRSP and SOC content resulted in multi-level improvement in soil properties. Our results highlight the importance of using GRSP and SOC as indicator during mine land reclamation.