Natural Vegetation Encroachment Improves Nutritional Conditions of Bauxite Residue Disposal Area

The deficiencies of certain nutrients limit plant growth in bauxite residue disposal areas. In this study, residue samples at different depths (0-2 cm, 2-10 cm, 10-20 cm, 20-40 cm, and 40-60 cm) and stacking ages were collected to analyze the changes of nutritional conditions following natural vegetation encroachment processes. With the encroachment of natural vegetation, the nutrient components improved greatly. The contents of organic carbon, total nitrogen, and available phosphorus increased from 5.6 g/kg to 10.8 g/kg, 0.07 g/kg to 0.73 g/kg, and 6.3 mg/kg to 24.9 mg/kg, respectively. With the increase of natural weathering time, microbial carbon, nitrogen, and phosphorus increased significantly. Natural weathering process and vegetation encroachment improved the circulation and accumulation of nutrient substances in bauxite residues.