Practices for rehabilitating bauxite-mined areas and an integrative approach to monitor soil quality

摘要

Mining activities cause severe impacts to soil, the restoration of which requires specific management, and proper evaluation and monitoring. In this research, our objectives were to study recovery strategies and integrate indicators for monitoring the reclamation of an agricultural soil after bauxite mining. Distinct fertilizations (nonfertilized control [CT], poultry litter [PL], chemical fertilization [CF], and PL+CF combined) and intercrops (bare soil with no intercrops [NI], grass [G], legume [L], and G+L combined) treatments were used as recovery strategies to restore soil capacity to sustain a coffee plantation. We selected 27 quality indicators to compare the premining condition, postmining (reconfigured topsoil), and 19months after the application of fertilization/intercrops treatments. We used univariate statistics to select soil quality indicators and multivariate analyses to group the selected indicators into organic, chemical, physical, and microbiological properties. From each group, one representative attribute was selected, and its averaged weight was summarized into a soil quality index (SQI). In postmining, the estimated SQI was approximately 65% lower than in premining. The SQI recalculated 19months after the application of fertilization (PL or PL+CF) and intercrops (G, L, or G+L) was 23% higher than in postmining and showed strong correlation with coffee bean yield (at 27months). Coffee bean yield was highest in plots with L or G+L receiving PL or PL+CF. We conclude that organic amendments and intercrops are suitable approaches to recover soil following bauxite mining, and soil indicators can be integrated to properly monitor the land reclamation progress.