Si amelioration of Al toxicity in barley ( Hordeum vulgare L.) growing in two Andosols

The influence of silicon on aluminium toxicity in barley ( Hordeum vulgare L. cv. Shunrai) was studied in two Andosols. Silicon sources were a solution of sodium metasilicate with pH adjusted to 5.0, silica gel, and an industrial waste, porous hydrated calcium silicate. The waste is produced in large amounts in the manufacturing processes of autoclaved light concrete, and has been used as a silicon source for rice plants. The addition of the waste increased the concentration of Si in the soil solution, soil pH and amelioration of aluminium toxicity was observed. The addition of silica gel and sodium metasilicate solution to both soils increased significantly ( p <0.05) the Si concentration of the soil solutions, but no amelioration of aluminium toxicity was observed. An amelioration of aluminium toxicity by the waste porous hydrated calcium silicate was probably due to the increase in soil pH rather than to the increase of silicon concentration in the soil solution.