Reclamation of coal mine spoil and its effect on Technosol quality and carbon sequestration: a case study from India

A field study was carried out to assess the impact of revegetation on Technosol quality in the post-mining sites (Central Coalfield Limited, India). The study evaluated community structure, biodiversity, Technosol quality, and carbon (C) dynamics in the post-mining ecosystem (PME). The multivariate statistical tool was used to identify the key soil properties, and soil quality was evaluated byusing Technosol quality index (TQI). One unreclaimed site (0years) and four chronosequences revegetated coal mine sites (3, 7, 10, and 15years) were studied and compared with an undisturbed forest as a reference site. Plant biodiversity indices [Shannon index of diversity (2.42) and Pielou's evenness (0.97) and Patric richness (12)] were highest in 15-year-old revegetated sites. Soil physicochemical and biological properties were recovered with the revegetation age. Soil organic C (SOC) stock significantly increased from 0.75Mg Cha(-1) in 3years to 7.60Mg Cha(-1) after 15years of revegetation in top 15cm of soils. Ecosystem C pool increased at a rate of 5.38Mg Cha(-1)year(-1). Soil CO2 flux was significantly increased from 0.27mol CO(2)m(-2)s(-1) in unreclaimed sites to 3.19mol CO(2)m(-2)s(-1) in 15-year-old revegetated site. Principal component analysis (PCA) showed that dehydrogenase activity (DHA), available nitrogen (N), and silt content were the key soil parameters that were affected by reclamation. A 15-year-old Technosol had a greater TQI (0.78) compared to the control forest soils (0.64) that indicated the suitability of revegetation to recuperate soil quality in mining-degraded land and to increase C sequestration potential.