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CALCIUM: ALUMINIUM EXCHANGE EQUILIBRIA IN CLAY MINERALS AND ACID SOILS 1
Author(s) -
COULTER B. S.,
TALIBUDEEN O.
Publication year - 1968
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1968.tb01537.x
Subject(s) - vermiculite , illite , montmorillonite , cation exchange capacity , soil water , chemistry , clay minerals , oxidizing agent , saturation (graph theory) , adsorption , ion exchange , mineralogy , inorganic chemistry , geology , soil science , mathematics , organic chemistry , ion , paleontology , combinatorics
Summary Exchange reactions between 0.0 in AlCl 3 solutions of different pH and Ca‐saturated montmorillonite, vermiculite, illite, and soils from the Park Grass Experiment at Rothamsted and the Deerpark Experiment, Wexford, Ireland, showed that Al 3+ and Al(OH) 2 + were adsorbed from solutions of pH > 4.0 and Al 3+ and H + from solutions of pH < 3.0. When Al was adsorbed, the cation exchange capacity of Ca‐saturated soils and clays increased. Conventional Ca: Al exchange isotherms showed that Al 3+ was strongly preferred to Ca 2+ on all soils and clays. The equilibrium constant for Ca: Al exchange, K , was identical for soils before and after oxidizing their organic matter and did not vary, for any exchanger, with Al‐saturation or the initial pH of the AlCl 3 solution. This proved the validity of the procedure used for calculating exchangeable Al 3+ . K values for Ca:Al exchange favoured Al 3+ in the order: vermiculite > Park Grass soil > Deerpark soil > illite > montmorillonite. The influence of surface‐charge densities of the clay minerals on this order is discussed and a method proposed and tested for calculating the K value of a soil from its mineralogical composition.