Composition, chemical speciation and activity of ions in the solution of Brazilian acid soils

Abstract

The knowledge of the chemical composition of the soil solution through chemical speciation is important for the monitoring of nutrient availability, soil fertility management and plant nutrition. The objective of this study was to evaluate the chemical composition and activity of Al, cations and anions by chemical speciation in solution of some Brazilian acid soils (AC, PE, RS and SC) submitted to liming and cultivated with soybean and maize plants. In addition, to identify the chemical elements responsible for the reduction of Al activity in the solution and its toxicity to plants. The predominant aluminum, calcium, magnesium, potassium, sulfate, chloride and nitrate species in all soils were: Ca2+ and Mg2+, K+, SO42-, Cl- and NO3- in all soils. In the treatments without limestone in the soils AC9, RS and CB predominated the species of P H2PO4- and in the soils PE and BR was the AlHPO4+. However, with liming the P form that predominated in all soils was H2PO4- and, to a lesser extent, HPO42-. The activity of the Ca2+ and Mg2+ ions was the main responsible for the neutralization of the toxic effects of Al3+ in the evaluated plants.