Assessment of the copper availability in the arable soils by different extractants

This paper presents an assessment of the copper availability in soil by different single extractions: DTPA (0,005 mol/L), CaCl2 (0,1 mol/L) and NH4NO3 (1 mol/L, DIN procedure). The research was carried out on 48 samples of the arable soils taken in the north-western part of the Republic of Srpska. Total Cu contents was also determined in the soil samples after the acid digestion (HNO3+H2O2). Copper contents in the extracts was determined by the atomic absorption spectrophotometry. Total soil Cu ranged from 7,7−42,9 mg/kg which corresponded to Cu-unpolluted soils. Low level of Cu mobility and availability was found in the investigated soils. In the average DTPA extracted 10,87%, CaCl2 0,31% and NH4NO3 0,44% of the total soil Cu. High statistically significant correlation (r=0,84) between the Cu contents extracted with DTPA and NH4NO3 was found, which implies that maximum allowed level of this element in the soil for the DTPA extraction procedure might be established. That conclusion has to be verified in future research including soils with high total copper content. Keywords: heavy metals, soil, extraction, pollution.