COMPARISON OF AA AND MEHLICH 3 METHODS FOR CALCIUM AND MAGNESIUM EXTRACTION FROM EASTERN CROATIA SOILS

Sa？etak Calcium and magnesium belong to a group of alkaline earth metals from lithosphere moderately mobile macronutrients which play an important role in plant nutrition. The aim of this paper was to compare quantities of extracted calcium and magnesium by ammonium acetate (AA) and by Mehlich 3 (Mehlich3) solutions from soils of eastern Croatia. The samples of the most representative soil types were gathered in five counties of eastern Croatia in 2012. After measuring the pH value and the overall carbonates being in soils, samples have been arranged into groups with less than 3.5% and more than 3.5% CaCO3. It was determined that Mehlich 3 method extracts more calcium and magnesium than AA method and differences were especially pronounced for calcium in soils containing more carbonates. In soils with less CaCO3 the statistically very significant correlation (P≤0.01) was determined between AA and Mehlich 3 methods regarding extracted calcium and magnesium. The results of these studies confirmed significant correlation (P≤0.01) between Mg AA and Mg Mehlich 3 methods in soils with more than 3.5% CaCO3 making both methods suitable for Mg determination regardless the soil CaCO3