Toward microbiome-assisted remediation: Vanadium–titanium magnetite mining reshapes cropland soil chemistry and rhizosphere microbiomes

Abstract Vanadium–titanium magnetite (VTM) mining can modify cropland soils and root-associated microbiomes with implications for crop health. However, how crop rhizosphere microbiomes reorganize under VTM-derived stress—particularly when bacteria and fungi are considered together—remains poorly understood. In the Hongge district (Panzhihua, China), we sampled bulk soils and rhizospheres of lettuce, rapeseed, and pea from croplands within the VTM mining influence zone (mining-impacted fields) and paired croplands outside the zone (reference fields). We measured soil chemistry and profiled bacterial and fungal communities using 16S rRNA and ITS amplicon sequencing, respectively. Mining-impacted soils generally showed a VTM geochemical imprint, neutral–alkaline pH, and reduced plant-available P and K. Bray–Curtis–based ordinations indicated a clear separation between mining-impacted and reference rhizospheres, and taxonomic profiles suggested host-dependent reassembly of both bacterial and fungal communities. Putative functional profiling suggested a shift toward stress-accommodation processes, and fungal guild assignments tended to tilt toward saprotrophic/endophytic categories. Mantel analyses identified pH as one of the strongest correlates of community turnover, whereas structural equation modeling was consistent with nutrient availability (available N/P/K composite) explaining a substantial portion of the VTM effect; the composite total-metal-load axis (Fe/V/Ti/Zn) showed limited explanatory power, especially for fungi. Together, these field-based, two-kingdom signals link VTM-altered soil chemistry to rhizosphere restructuring in edible crops and provide actionable indicators for crop health management.