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Bauxite mining requires the removal of the vegetation and topsoil, thus causing considerable impacts on both natural and managed ecosystems. This is typically the case of agricultural activities across Minas Gerais, South‐eastern Brazil, where bauxite mining often displaces pastures and coffee plantations. In this study, our objective was to assess the effects of chemical and organic fertilizations combined with cover crops on the re‐establishment of coffee plantations following bauxite mining. The experiment consisted of a split‐plot design which main plot received 4 types of fertilization: no fertilization, chemical fertilization (CF), poultry litter (PL), and CF + PL. In subplots, 4 cover crops were cultivated in between the rows of the coffee plantation, including: no cover crops, grass (Brachiaria brizantha [B]), legume (Stylosanthes spp. [S]), and B + S. We had 4 blocks as replicates. Organic and chemical fertilization (PL + CF) combined with cover crops (B + S) led to significant recovery of soil organic carbon (SOC), soil organic nitrogen (SON), and KMnO4‐oxidizable SOC. PL + CF and B + S also led to SOC increments of 14.5 g kg−1 soil (0–10‐cm depth). Based on isotopic data (13C), both cover crops, isolated or combined, contributed to the recovery of SOC. Over 3 consecutive harvests, coffee bean yield was consistently above 1,800 kg ha−1 under PL or PL + CF, except when B was the only cover crop. Managing fertilization and cover crops can determine the recovery of SOC, SON and the capacity of soil to sustain the re‐establishment of coffee plantations following bauxite mining.

Summary Particle‐size distribution (PSD) determines soil C‐saturation; that is, the capacity of the mineral matrix to protect soil organic carbon (SOC) against decomposition. However, the mechanistic connection between PSD and C‐saturation is not entirely clear, especially for Oxisols. To address this issue, we carried out a 12‐month incubation experiment; 13C‐labelled litter inputs equivalent to 0, 4.5, 9.0 and 18.0 mg C g−1 soil were applied to samples of six Brazilian Oxisols, taken from depths of 0–10, 10–20, 20–40 and 60–100 cm. The effect of PSD on SOC protection and C‐saturation was assessed by ‘diluting’ the mass of the clay + silt fraction (< 53 µm) by adding fine sand (150–250 µm) in increments of 0, 20, 40 and 80% relative to the fine earth fraction (< 2 mm). Carbon‐saturation level (CSL) was assumed to be a linear function of clay + silt contents, whereas C‐saturation deficit (CSD) was the difference between the CSL and original SOC content in the samples. After the incubation, litter‐derived C within the clay + silt fraction increased exponentially with CSD. Carbon saturation was indicated by an asymptotic relation between the litter‐derived C in the clay + silt fraction and the additions of litter‐C. For clay + silt contents as small as 15%, CSL was achieved at 61.6 g C kg−1 clay + silt. Conversely, when the proportion of the fraction < 53 µm exceeded 60%, CSL occurred at 33.4 g C kg−1 clay + silt. Thus, a PSD‐dependent hierarchy of SOC protection and C‐saturation in Oxisols can be inferred. Our observations support a conceptual model of C‐saturation where surface interactions provide the dominant mechanism of SOC protection at small clay + silt contents. At large clay + silt contents, physical protection of SOC resulting from the spatial arrangement of fine‐sized minerals defines C‐saturation. Highlights The extent to which particle‐size distribution affects mechanisms that define C‐saturation are unclear. For a clay + silt content of 15%, C‐saturation occurred at 61.6 g C kg−1 clay + silt. When the proportion of the fraction < 53 µm exceeded 60%, CSL occurred at 33.4 g C kg−1 clay + silt. A PSD‐dependent hierarchy of SOC protection and C‐saturation in Oxisols can be inferred.

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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 19 months 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 19 months 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 27 months). 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.

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