Effects of soil amendments on arsenic and cadmium uptake by rice plants (Oryza sativa L. cv. Koshihikari) under different water management practices

Concentrations of arsenic (As) and cadmium (Cd) in rice grains are of public concern for human health. We conducted field experiments to investigate the effects of soil amendment applications, combined with different water management practices, on As and Cd uptake by rice plants (Oryza sativa L. cv. Koshihikari). Prolonged flooding, practiced for pre-heading 3 weeks and post-heading 3 weeks, led to elevated As concentrations in the soil solution and rice grain. Rainfed water management, in which no irrigation was practiced after midseason drainage until harvest, led to elevated Cd concentrations in the soil solution and rice grain. Application of short-range-order iron hydroxide (IO) reduced As uptake by rice plants, whereas Cd uptake was reduced by the application of converter furnace slag (CFS). However, it was difficult to simultaneously reduce the As and Cd uptake by a single countermeasure of the water management practice or the soil amendment application. Prolonged flooding combined with the application of IO, or rainfed water management with the application of CFS, were promising measures for the simultaneous reduction of As and Cd uptake by rice plants.