Potential alteration of iron–humate complexes by plant root exudates and microbial siderophores

Background Two humic acids extracted from a volcanic soil (HA1) and a leonardite (HA2) were used to form insoluble complexes with iron metals. To simulate the rhizospheric processes that displace iron from complexes of humic molecules and solubilize the soil humeome, the insoluble iron–humates were treated with a solution of siderophore deferoxamine mesylate (DFOM) and a mixture of citric, oxalic, tartaric and ketoglutaric acids, at different concentrations and contact times.