Ion Exchange Equilibria Involving Aluminum in a Kaolinitic Ultisol

Abstract

Cation exchange equilibria in an acid Ultisol profile involving K‐Al, Ca‐Al, K‐Ca, Na‐K, and Na‐Ca exchanges were studied. Selectivity coefficients, surface activity coefficients and free energy changes were computed using the thermodynamic formulations.In exchange equilibria involving Al, the magnitude of selectivity coefficients Kc, was affected by pH, surface composition, and hydrolysis of Al. In equilibria not involving Al, good reversibility for K‐Ca, Na‐K and Na‐Ca exchanges was obtained. Potassium was selectively adsorbed in all horizons of the profile. The over‐all selectively sequence follows the order of K>Al>Ca≈Na.

Potassium–calcium and potassium–magnesium exchange equilibria in an acid savanna soil from northern Nigeria

“…Udo (1978) reported a preference for K + by the exchanger phase to Ca 2+ in soils from western Nigeria dominated by kaolinite. In kaolinitic Ultisols from western Nigeria, Pleysier et al (1979) found a selectivity sequence of K N Al N Ca. Seven out of nine weathered soils from Malaysia and Sri-Lanka studied by Talibudeen (1972) exhibited preference for K + over Al 3+ .…”

Nutrient Leaching in Undisturbed Cores of an Acidic Sandy Podosol Following Simultaneous Potassium Chloride and Di-Ammonium Phosphate Application

“…The very small number of specific sorption sites in this Podosol soil can be attributed to the absence of micaceous clay minerals with an interlayered structure (e.g. illite and vermiculite), and kaolinite, which have a high affinity for K + ions (Pleysier et al 1979;Levy et al 1988;Phillips et al 1988a; Barbayiannis et al 1996;Chappell and Evangelou 2000).…”

“…Both of these sources of charge exhibit a stronger preference for multivalent cations relative to monovalent cations (e.g. Pleysier et al 1979;Phillips et al 1988a;Barbayiannis et al 1996). Therefore, the higher concentrations of organic matter and hydrous Fe and Al oxides in the 0 -30 and 30 -50 cm depth materials may explain the lower k K and k NH 4 for these materials relative to that for the >50 cm depth.…”

Heterovalent cation exchange in two savanna soils of different lithogenic origin as described by the Rothmund–Kornfeld model

“…Whether this distribution pattern is a consequence of preferential adsorption of Ca 2+ or Mg 2+ to K + or a consequence of 'luxury consumption' of K + by crops is not well understood. But cation exchange studies from savanna soils of Western Nigeria indicated a preferential K + to Ca 2+ and Mg 2+ retention by the soils (Udo, 1978;Pleysier et al, 1979). A recent study by Agbenin and Yakubu (2007) also established a preferential K + adsorption to Ca 2+ and Mg 2+ in a savanna soil whose formation had been strongly influenced by volcanic activities.…”