Brassica carinata planting pattern influences phytoextraction of metals from a multiple contaminated soil

Due to the potential environmental risks resulting from the use of chelants it is necessary to explore different approaches in the remediation of metal-contaminated soils. This study focussed on the removal of metals (Cu, Mn, Pb and Zn) from a multiple-metal contaminated soil by growing Brassica carinata under different planting patterns (monoculture, co-planted or in succession with barley). The results showed that in comparison with Brassica monoculture, both co-planting and succession increased soil extractable metal concentrations, which resulted in a higher concentration of metals in the above-ground parts of B. carinata, especially in the succession planting. The reduction of dry biomass in Brassica co-planted with barley strongly limited metal uptake by plants. It was suggested that root exudates played an important role in solubilising metals in soil and in favouring their uptake by roots. The improved phytoextraction efficiency of B. carinata resulting from the succession planting in comparison with monoculture indicates the potential for a naturally-assisted approach to metal-contaminated soil remediation.