Soil organic carbon in post-coal mining land under 10-year-old Acacia mangium stand

Coal mining activities have caused severe environmental degradation, particularly in the form of soil structure damage, loss of natural vegetation, and a decline in soil organic carbon (SOC) reserves. This study aimed to evaluate the amount of SOC stock as an indicator of restoration success and its contribution to long-term carbon stock. Soil sampling was conducted in a post-mining area under a 10-year-old Acacia mangium stand at PT. Ratu Samban Mining, Batu Beriang Village, Pematang Tiga District, Central Bengkulu Regency, Bengkulu Province, at depths of 0–10 cm, 10–20 cm, and 20–30 cm. The samples at each depth were analyzed for SOC content, pH, bulk density, and soil texture (percentages of sand, clay, and silt). Statistical analyses used were ANOVA, regression, and correlation. The results showed SOC stock of 23.70 Mg ha⁻¹, 20.75 Mg ha⁻¹, and 16.88 Mg ha⁻¹ at depths of 0–10 cm, 10–20 cm, and 20–30 cm, respectively. These values are close to the SOC stock of secondary forests (28.5 Mg ha⁻¹). In addition, clay content and soil pH had significant correlations with SOC. Reclamation through 10 years of revegetation using A. mangium stands effectively increased SOC stocks.