Effects of biochar complex conditioner on properties of cadmium contaminated soil and cadmium absorption and physiological characteristics of Brassica chinensis

ObjectiveThe present study was conducted to study the feasibility of utilization of biochar complex condi-tioner (biochar, peat and lime) in repairing light cadmium(Cd) contaminated farmland soil, in order to provide a scien-tific basis for its utilization on light Cd contaminated farmland. MethodA pot experiment was carried out in net house to investigate effects of biochar complex conditioner. Four treatments namely four dosage of biochar complex conditioner in-cluding 0(CK), 80, 160 and 240 g/pot were applied in this experiment. The four treatments were indicated as H0, H1, H2 and H3 respectively. Each treatment had one pot fitted with 4 kg soil and was repeated four times in a bid to study ef-fects of different -proportion biochar complex conditioners on soil characteristics, Cd uptake of Brassica chinensis and physiological parameters. ResultBiochar complex conditioner significantly improved soil pH, microbial nitrogen(MBN) content and urease activity(P<0.05, the same below), and reduced soil available Cd concentration(up to 37.1%), soil microbial carbon(MBC) content and acid phosphatase activity. In addition, biochar complex conditioner reduced Cd concentration(up to 85.7%), malondialdehyde(MDA) accumulation as well as activity of superoxide dismutase(SOD), catalase(CAT), peroxidase(POD) activity in plant of B. chinensis. Cd content of B. chinensis was down to 0.10 mg/kg, which met food safety standards. It was found that low dosage(2%) of biochar complex conditioner can increase yield of B. chinensis while high dosage had negative effect. ConclusionBiochar complex conditioner is effective in reducing soil Cd activity and improving soil conditions as well as inhibiting Cd uptake of plant. It means that biochar complex condition-er can be applied to remediation of Cd contaminated soil and the most appropriate dosage is 20-40 g/kg.