Aluminum mobilization by sulfuric and nitric acids from some Polish soils

Study was conducted to determine the influence of sulfuric and nitric acids on the Al solubility for brown, black, peat and calcareous soils. The results show that the amounts of labile aluminum mobilized depend significantly on the soil types and horizons. Much more labile aluminum is mobilized in the brown soil than in the black, peat and calcareous soils. The greatest difference in labile aluminum mobilization is between agriculturally managed soils and unfertilized soils. It is apparent that long-term ammonium fertilization significantly increase soil aluminum solubility. The mobilization of labile aluminum in the soil profile increases also with soil depth. The trivalent aqueous aluminum activity relative to the hydrogen ion activity does not comply with a gibbsite or gibbsite-like mineral solubility control. In most cases, aluminum mobilization by nitric acid is higher than by sulfuric acid. Nitric acid mobilized less aluminum than sulfuric acid only at high acid concentrations (> 5.0 mM) and in soils with high organic matter content.