Progress and future prospects in co-planting with hyperaccumulators: Application to the sustainable use of agricultural soil contaminated by arsenic, cadmium, and nickel

Co-planting two or more species on the same piece of land, with overlapping time or not, has been suggested to increase both crop production and long-term sustainability. On soils that are slightly or moderately contaminated with heavy metals, hyperaccumulators have been co-planted with crops to clean the soil and produce safe agricultural products. Despite the increasing number of greenhouse experiments and field trials that investigate the co-planting mechanisms and efficiency, the consistency, stability, and applicability of this technology and its contribution to sustainability remain unclear. From published literature, we collected 118 co-planting combinations involving hyperaccumulators, and compared them with their monoculture controls. Co-planting averagely decreased the shoot arsenic concentration by ∼23.4% and cadmium by ∼13.4%. Co-planting controls the crop contamination as long as the hyperaccumulator and crop species are correctly selected, and the soil heavy metal is within the safe range. Further, a sustainability assessment criterion for the utilization of contaminated agricultural soil was proposed, taking As-contaminated soil as an example. A decision framework and a guideline for co-planting were established to aid in the decision-making. The outlook of co-planting as a sustainable solution and the future development were prospected.