The heavy metal availability in long-term polluted soils as affected by EDTA and alfalfa meal treatments

A 38-day incubation experiment was carried out in order to evaluate the response of plant-available portions of heavy metals in long-term contaminated arable and grassland soils on addition of ethylenediaminetetraacetic acid (EDTA) and alfalfa (Medicago sativa L.) meal. Soils with different soil management (arable and grassland) from the vicinity of a lead smelter were used in the experiment. Readily available heavy metal fractions of Cd, Pb, Zn and Cu increased in the presence of EDTA at the beginning of experiment. The increase of heavy metal availability was higher in the arable soil with lower content of soil organic carbon than in the grassland soil. Addition of EDTA increased content of K2SO4-extractable carbon which remained higher throughout the overall time of experiment. During the first part of the experiment, the alfalfa meal addition decreased the available metal concentrations in the EDTA-treated grassland soil whereas no effect of alfalfa meal was observed in EDTA-treated arable soil.