Influence of Soil Amendments on Uptake and Accumulation of Cd and Pb in Maize (Zea mays L.)

China has a large population in comparison with its arable land area, as well as environmental problems caused by metal pollution, leading to significant food supply pressure. Therefore, safe agricultural production in metal-contaminated soil is of great significance. To explore the effectiveness of techniques designed to inhibit metal uptake and accumulation in maize cultivated in calcareous metal-contaminated soil, a pot experiment was performed. Effects of KH2PO4 (P), Na2SiO3 (S), chicken manure (M), bentonite (B), P+M, S+M, P+M+B, and S+M+B on Cd and Pb concentrations in maize grain were assessed. Amendments of P, P+M, and P+M+B fortified into the soil reduced soil Cd and Pb availability significantly and decreased the soil pH, but other amendments did not cause such changes. Results also showed that all tested soil amendments improved maize yield and decreased grain Cd and Pb concentrations. Among the amendments, P+M was most effective. A high dose increased maize yield by 48.2% and 38.9% for low-Cd-accumulating cultivar Tiantai 60 (maize A) and high-Cd-accumulating cultivar Longping 206 (maize B) and decreased Cd content in grain from maize A and maize B by 64% and 41.9% and decreased Pb content by 61.0% and 52.3%. Experimental results demonstrated that addition of P+M into the calcareous soil could reduce soil metal bioavailability and ultimately reduce metal concentrations in grain to levels deemed safe for human consumption.