the correlation of the values of plant-avalilable pb and cd in soil determined using different types of extragens

The plant-available amount of Pb and Cd in soil was determined by extraction using the solutions: 1) 0.5 M Na2EDTA, pH 5.2; 2) 1 M KCl, pH 7.0; 3) 0.1 M KCl, 0.05 M Na2EDTA, pH 6.2; 4) 2 % CH3COOH, pH 2.5 and 5) 1 M CH3COONH4, pH 4.8. Chernozem and hydromorphic black soil types from the Middle Banat were used. It can be concluded that the values of the plant-available amounts of Pb and Cd in a soil depends on the stability constants of their complexes with ligands in the extraction solution. The conversion factors for the recalculation of the amounts of Pb and Cd obtained using the citted extractants have been calculated.