PLANT AVAILABILITY OF CADMIUM IN SOILS .1. EXTRACTABLE CADMIUM IN NEWLY AND LONG-TERM CULTIVATED SOILS

Effects of long-term use of phosphate fertilizers on extractable soil Cd in relation to its concentrations in plants were investigated. ''Pa ired'' soil samples were collected from newly and long-term cultivated fields and analyzed for Cd by extraction with NH4OAc, DTPA, NH4OAc-ED TA, NH4NO3, HCl and CaCl2. Plant samples were also collected and analy zed for Cd. Significant differences in extractable Cd by all the extra ctants except NH4NO3 were observed between the newly and long-term cul tivated soils. The Cd concentrations in plants were not increased by t he elevated extractable Cd. Although significant relationships were ob served between plant Cd and extractable soil Cd, none of the extractan ts used alone gave a good assessment of plant-available Cd for all the samples used in this study.