Investigating the Effect of Different Biochars on Cadmium Uptake and Growth of Lettuce Plant (Lactuca sativa L.) in a Cadmium spiked Soil

Biochar as a soil amendment can control bioavailability of heavy metals in contaminated soils and can reduce the hazard of their transferring to the food chain. In order to investigate the effects of biochar derived from the apple and grape pruning wastes and wheat straw on bioavailability of Cd and growth of lettuce plants an experiment was conducted in a completely randomized design under greenhouse condition with the facrors of: 1) the concentration of Cd (0, 10 and 20 mg kg-1), 2) type of biochar (apple pruning, grape pruning and wheat straw) and 3) biochar level (0 (B0), 2 (B2) and 5 (B5) % w/w) in 3 replications. At the end of the lettuce growth period, some parameters including shoot dry weight, root dry weight, Cd concentrations in root and shoot, translocation factor (TF), bio concentration factor for shoot and root (BCF), and bioavailability of Cd in soil were measured. The results showed that the increase of the soil pollution level, raised the   intensity of the Cd bioavailability, Cd concentrations of shoots and roots, bio concentration factor of shoot and root (BCF). Furthermore, with increasing the level of biochar in soil, bioavailable Cd, Cd concentrations of roots and shoots were decreased in treatments (B5> B2> B0). Bioavailable Cd concentrations in soil in biochar treatments including apple pruning, grape pruning and wheat straw at the level of 5% w/w were decreased, by 46.81, 65.96 and 76.59 %, as compared to control respectively. Therefore biochar impact on decreasing Cd bioavailability depended on its raw material, biochar amount and metal concentrations.