Aluminium speciation and pH of an acid soil in the presence of fluoride

Abstract

SUMMARY The aim was to determine whether the addition of F to an acid soil reduces the concentration of free Al 3+ and other forms that have been shown to be toxic to plants. The ability of two different extracts to reflect Al speciation in the soil solution was also investigated. Addition of F (0‐5.2μmolg −1 ) to an acid soil (pH 4.15, soil solution) increased the pH and total concentrations of Al and F in the soil solution whereas Al 3+ remained constant or decreased. Soil solution pH, total soluble Al and Al extracted by 0.01 m CaCl 2 are not good predictors of the likelihood of aluminium toxicity in soils containing soluble fluoride.