For the purpose of calculating the banding energies of sodium and potassium ions in relation to the electric charge of soils,ration activities of the suspension in equilibrium with various types of soils or clays carrying different electric charge were measured with glass electrode.It was found that far the same soil type the bonding energy was a function of the relative proportion of the clay concentration to the total concentration of rations in the system.The bonding energy of a lateritic soil was changed when the soil particles were coated with a layer of ferric oxides so as to alter their electric charge.Changes of bonding energy were also found when the ration-exchange capacity of a bentonne clay was decreased by thermal treatment.With respect to the soil type,it was shown that the bonding energies of the yellowish brown earth were almost double thar of the lateritic soil.The pH of the medium affected the bonding energy markedly,even for the bentonite clay or ration-exchange resin with little or no variable electric charge.