Abstract

                                Under permanent irrigation agriculture, the quality of irrigation determines the equilibrium cationic composition of soil colloids. Much understanding has been made on the attainment of equilibrium conditions through the study of ion exchange properties of soil colloidal surface. The colloidal surfaces with counter ions behave like condensers, and electro-kinetic theory of double-layer on the surface was first developed by Helmotz (1881). To explain the exponential decrease on ionic concentration from surfaces towards the bulk of the liquids was further developed by Guoy (1910) and later by Chapman independently on the diffused double layer theory. Pauli and Valko (1929) used empirical hyperbolic equations to describe the ion exchange phenomenon. Gans (1913) and Kerr (1928) used Law of Mass action principles to study ion-exchange phenomenon. The kinetically derived formulae of Gapon (1937) and Jenny (1936) also follows the Law of Mass action.

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