Phytomanagement with forage grasses for sustainable remediation of contaminated tailings soil: enhancing soil functionality and microbial communities

Tailings-contaminated soils represent an underutilized land resource. Reclaiming these soils with forage grasses can restore landscapes, mitigate metal pollution, and support phytoremediation and forage production. This study evaluates five forage grasses for reclamation in heavily contaminated tailings soil. All grasses demonstrated strong adaptability, likely due to their metal exclusion traits, with bioconcentration factors < 0.11 for Cd and < 0.06 for Pb and Zn. Notably, Pennisetum purpureum “Sweet” accumulated metals below the permissible limits for fresh grass silage. Grass reclamation significantly improved soil multifunctionality, enhancing physicochemical properties, enzyme activities, and rhizosphere bacterial α-diversity and biomass. It also altered bacterial and fungal community composition and enriched nitrogen-cycling bacteria, with higher abundances of denitrification-related genes (nirK, nosZ) relative to bare tailings soil. Greenhouse experiments further demonstrated that naturally restored rhizosphere microbial communities improved forage grass adaptability and facilitated heavy metal stabilization in roots, reducing translocation and promoting plant growth. Among the tested grasses, P. purpureum “Sweet” exhibited the lowest metal accumulation, making it promising options for forage production on contaminated soils. This study underscores the potential of forage grasses and their associated microbial communities to enhance soil rehabilitation and promote ecological restoration in mining-impacted environments.