Rice husk and charred husk amendments increase porewater and plant Si but water management determines grain As and Cd concentration

Abstract Purpose Rice is a staple crop worldwide and silicon (Si) hyperaccumulator with Si levels reaching 5–10% of its mass; this can result in desilication Si-deficiency if plant residues are not managed correctly. also uniquely subject to arsenic (As) cadmium (Cd) contamination depending on soil conditions. Our goal quantify the effects rice husk (a Si-rich milling byproduct) amendments different water management strategies uptake Si, As, Cd. Methods We employed 4 amendment treatments: Control (no husk), Husk (untreated Biochar (husk pyrolyzed at 450 °C), CharSil combusted > 1000 °C). Each these was studied under nonflooded, alternate wetting drying (AWD), flooded pot study. Porewater chemistry mature elemental composition were measured. Results treatments, along flooding, increased porewater Si. Vegetative tissue As decreased increasing but grain Cd primarily controlled by management. Grain inversely correlated simultaneously minimized redox potential (Eh) range 225–275 mV soil. Ferrihydrite root iron plaque translocation from grain, able increase ferrihydrite content. Conclusion conclude moderate rates (i.e., years’ worth) minimal pretreatment strongly increases content may be sufficient decrease low