Continuous Rotation of Three Large Biomass Crops With High Bioconcentration Factor of Cadmium Can Effectively Repair Contaminated Farmlands

Abstract

Traditional phytoremediation is one means for remediation of heavy metal pollution. For developing countries, the key factor in promoting the practical application of phytoremediation in polluted soils is selecting suitable plants tolerant to heavy metals and using these to produce products with economic value. A chicory-tobacco-peanut, three-season, rotation field experiment was carried on the utilization and remediation of cadmium (Cd) in contaminated farmlands. The results showed that all three crops had a strong capacity to accumulate Cd, with bioconcentration factors of chicory, tobacco, and peanut 6.61 to 11.97, 3.85 to 21.61, and 1.36 to 7, respectively. The yield of total dry biomass and phytoextraction efficiency for Cd reached 32.4 t ha-1 and 10.3% per year, respectively. The aboveground tissues of the three crops accounted for 83.9–91.2% of the total biomass in this rotation experiment. The content of peanut grain and oil met the National Food Safety Standard of China (0.5 mg kg-1, GB 2762-2017) and the Food Contaminant Limit of the European Union (0.1 mg kg-1, 18812006). Therefore, in addition to being used for phytoremediation in contaminated soils, this crop rotation system can also lead to economic benefits for local farmers.