Published online by Cambridge University Press: 09 July 2018
Solutions obtained from soils in the Galicia Region of NW Spain had considerably lower activities of Al3+ when obtained by a speciation procedure (fractionation with an ionic column and application of specific software) than when obtained from concentrations of reactive Al (colorimetry with pyrocatechol violet) by a calculation that only considers simple hydroxylated species. Using the speciation method, many of the solutions obtained from surface horizons are unsaturated for most minerals, especially in granitic areas.