Simulation of silicon leaching from flooded rice paddy soils in the Red River Delta, Vietnam

•Vertical transport results in a potential loss of upto 10 ton Si ha−1 from paddy soils with two, annual rice-cropping cycles.•This loss by leaching is about one order-of-magnitude higher than potential rice uptake.•Our experiments suggest that a strong deficiency of Si might occur near the end of the flooding period.•A “peak application” of Si during the deficiency stage may be necessary to insure sufficient Si transfer to rice plants.