The Effect of Irrigation Control and the Application of Soil Ameliorators on Cadmium Uptake in Paddy Rice

In order to identify the effect of cadmium uptake by soil ameliorators in rice plants, compost, lime, silicate, and phosphate were treated. Plants were grown with irrigation water containing cadmium and treated with two irrigation systems, intermittent irrigation and continuous submersion. Soil pH was higher at the panicle formation stage compared to other growing stages. However, Eh value was decreased as growing stage was proceeded. Eh values measured at the continuous submersion plots were lower than those at the intermittent irrigation plots. Cadmium contents in the both leaves and roots of rice plants grown at the continuous submersion plots were lower than intermittent irrigation plots in the middle of growing season. Among the continuous submersion plots, cadmium uptake was highly reduced at the both silicate and lime treated plot compared to other treatments. In the harvest season, cadmium contents in the both leaves and brown rice were higher at the intermittent irrigation plots than the continuous submersion plots. Cadmium uptake was highly reduced at the compost and lime mixture plot compared to other treatments among the continuous submersion plots. Soil pH was negatively correlated with the cadmium contents of the both shoot and brown rice while Eh was positively correlated with those. The cadmium content of shoot was positively correlated with that of brown rice in the harvest season.