Plant biomass amendment regulates arbuscular mycorrhizal role in organic carbon and nitrogen sequestration in eco-engineered iron ore tailings

•Plant biomass type influences AM role in organic carbon (OC) and nitrogen (N) sequestration in Fe-ore tailings technosol.•AM symbiosis enriched OC sequestration within macroaggregates of Lucerne hay amended tailings.•AM symbiosis increased N stabilization by minerals within aggregates of Sugarcane mulch amended tailings.•Carboxyl-rich organics associated with Fe/Si-rich minerals contributed to OC sequestration.•Water deficit weakened AM role in OC and N sequestration in the tailings.