Effects of soil amendments and foliar selenium applications on soil cadmium immobilization and wheat accumulation

Wheat cadmium (Cd) contaminationis one of the environmental and agricultural concerns worldwide. Here, the effects of foliar selenium (Se) and soil amendments (lime, biofuel ash and sodium sulfide (DSO), iron mine tailing and alkali lignin (MX)) applications on the soil Cd fractions and wheat Cd accumulations were studied by incubation, greenhouse pot, and field plot experiments. The results showed that in soil incubation experiment, lime and MX applications significantly increased soil pH and DSO applications significantly decreased soil pH, while all the three amendments can significantly reduce the available Cd fractions by 16-21%. Foliar spraying can significantly increase the growth and yield of the high-Cd-accumulating-cultivar (Puxing5). In the greenhouse experiment, lime and MX applications considerably decreased grain Cd concentrations by 53-56% and 41-52% for Puxing5 and by 9-38% and 23-28% for Zhoumai30, respectively. In the field experiment, the Cd concentrations were significantly reduced by 67-69% and 69-74% in Puxing5 grain by lime and MX applications, respectively. DSO applications also significantly reduced Cd concentrations in grains by 56-59% for Puxing5 and by 22-27% for Zhoumai30 in the greenhouse experiment, but in contrast, increased Cd concentrations in field experiment by 20-23%. Our results implicate that the incubation and greenhouse experiments are necessary to be verified in the field and the foliar Se application is recommended when considered both the financial costs and production safety.