Charge distribution of selected venezuelan soils with some pedogenic and agrotechnological implications

Abstract

Abstract A study of the electrical charge distribution of selected Venezuelan soils (two Oxisols, two Ultisols, and one Alfisol) by potentiometric titration (PT) and ion adsorption (IA) procedures, showed that all soils have a predominance of negative charge at their natural pH level and within the experimental pH range used (3.5–7.5). The only exception was the Amazonas 2 soil, which has a point of zero net charge (PZNC) at pH 3.5. Potentiometric titration (PT) results allowed us to find the point of zero salt effect (PZSE) of these soils, which is related to their pedogenetic development. The order found, from older to younger, was: Guanipa (Oxisol) > Amazonas (Oxisol) > Lomas de Cubiro (Ultisol) > Altos de Pipe (Ultisol) > Barinas (Alfisol). The Stoop's method, used to determine the PZSE of the soils, was found to be a more efficient and shorter way than PT for this purpose. Ion adsorption (IA) was a more realistic way than PT to determine charge distribution for the studied soils. The soils were class...