INFLUENCIA DEL CONTENIDO Y FORMAS DE Al EXTRAÍBLE EN LOS MECANISMOS DE NEUTRALIZACIÓN DE ÁCIDOS DE DOS
HORIZONTES ÚMBRICOS

J.C. NÓVOA MUÑOZ, T. TABOADA RODRÍGUEZ, E. GARCÍA-RODEJA GAYOSO

Dpto. Edafoloxía e Química Agrícola. Fac. Bioloxía. Universidade de Santiago. Rúa Lope Gómez de Marzoa s/n. Campus Sur. 15782 Santiago de Compostela.

Abstract

Acid buffering mechanisms of two umbric horizons, representative of aluminic soils and from soils with andic properties, have been studied using an experimental acidification (batch type) in an acid range from 0 to 30 cmolH+.kg-1 of soil. Depending on the intensity of proton load, cation exchange and dissolution of Al compounds are the dominant acid buffering mechanisms in both soils. Reduction in “reactive” Al content after soil acidification responded to 84-100% of Al released. Aluminium-organic matter complexes (in aluminic soil) and inorganic amorphous Al (in the soil with andic properties) are likely the sources of this Al. Soil organic matter seems to control Al solubility in both horizons, although the results not discard the role of mineral phases as Al(OH)3 and 1:1 phyllosilicates.

Key words: soil acidification, aluminic soils, andic properties, acid buffering mechanisms, “reactive” Al, Al-organic matter complexes, Al solubility.