Toward microbiome-assisted remediation: Vanadium-titanium magnetite mining reshapes cropland soil chemistry and...

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.