Technical solutions for the safe utilization of heavy metal‐contaminated farmland in China: A critical review

China is suffering from farmland heavy metal pollution. Different strategies have been explored in the past decades to address the problem, mainly metal removal, substitute planting, and safe farming. Safe farming aims to produce metal-safe food crops in heavy metal-polluted farmland without purposefully removing the excess metals. Safe farming was intended to address the soil-borne food heavy metal issue and has been advocated as a priority solution for farmland pollution by the government. Many conventional and novel technologies have been tested for safe farming in recent years. Although most reduced heavy metals in grains, none of the technologies alone were found to be sufficient in field practice to meet national food standards. The current best practice is recognized as the combination of several agronomic measures, including pollution-safe cultivars, optimal water management, liming, and conventional metal immobilizers. Unfortunately, field trials have not achieved a robust technical framework effective for farmland with different soil properties and climatic conditions. We propose that a practical technical framework may be biotechnology centered with a minimal use of chemical immobilizers, particularly liming and phosphate minerals. Foliar sprays and microbial biosorbents seem promising for safe farming. A biotechnology-centered framework may largely simplify the field practice of safe farming and is more acceptable to governments and farmers.