The total and available concentrations of essential trace elements in agricultural soils of eastern croatia

UDK 631.41:546.4(497.6) The research objective was to determine the influence of basic soil chemical properties on total concentration and available fractions of essential trace elements in the soil. Agrochemical soil analysis were conducted at two localities of different soil properties Berak and Vinogradci in eastern Croatia. The soil at the site Berak was eutric cambisol of neutral reaction (pH average (H2O) 7.20), while the soil in Vinogradci was luvisol of slightly acid reaction (average pH (H2O) 5.87). Both soils were poor in organic matter and well supplied with phosphorus and potassium. As expected, at both analyzed sites the highest average concentrations were determined for total Fe, Mn and Zn followed, and the lowest concentrations were for total Cu. Higher total concentrations of analyzed microelements were recorded at the Berak site. The total concentrations of Zn and Cu in all analyzed soil samples were below the maximum permissible concentrations. The highest average concentration of available microelements fraction by EDTA Extraction, were at the Berak site determined for Mn (50.52 mg/kg), then Fe (21.77 mg/kg), Cu (4.78 mg/kg), and the lowest for Zn (1.47 mg/kg). At the Vinogradci site average concentrations of available fraction of microelements determined by EDTA extraction were the highest for Fe (77.09 mg/kg), then Mn (30.75 mg/kg), Cu (4.36 mg/kg), and the lowest for Zn (1.76 mg/kg). Identical order of average concentrations at both sites was also recorded for extraction with DTPA solution. Comparing available fraction of microelements by localities, higher average concentrations of Mn and Cu were found at the site Berak, while on site Vinogradci higher average concentrations were of Fe and Zn. At both sites the DTPA method extracted more of Fe and Mn, an average of 51.06% and 6.39% more than the EDTA method, but the method EDTA extracted more Zn and Cu, an average of 127.10% and 100.40% than DTPA method. The smallest share of the available fraction of the total concentration was recorded for Fe (0.06% by EDTA -0.09% by DTPA ), followed by Zn (1.20% by DTPA - 2.74% by EDTA) and Mn (5.93% by EDTA – 6.31% by DTPA), while the largest share was observed for Cu (10.92% by DTPA and 21.84% by EDTA).