Cadmium contamination of soils and rice plants caused by zinc mining IV. Use of soil amendment materials for the control of Cd uptake by plants

Abstract

Abstract In view of the difficulty in practicing water management as a measure to prevent the production of high Cd rice, alkaline or calcareous soil amendment materials were examined, concerning their pH effect on the availability of soil heavy metals. 1. In the experiment conducted on the contaminated paddy field, the essential Cd uptake by the plant occurred after the ear-forming stage and was reduced remarkably by a basal application of the amendment materials followed by top application, depending on the activity of raising the soil pH. Combined use of calcium silicate and fused magnesium phosphate for a basal dressing was most effective on Cd uptake, producing rice of the lowest Cd content, one fifth of the control. 2. The content of Cu in rice also decreased with the treatment to an extent second to Cd, while that of Zn and Pb decreased in straw but hardly changed in rice. Cu seemed fastest in the straw-to-grain movement which was also promoted by the treatments. 3. Soil Cd and Cu were less soluble...