Effetto dei trattamenti termici e chimici sulla capacità di scambio della frazione argillosa di alcuni suoli bruni

Variations of permanent and pH-dependent charges of soil clays subjected to thermal and chemical treatments were studied. The permanent charge was considerably reduced either on heating samples at 400°C or on acid treatment. A strong hysteresis of the permanent charge occurred in the heated samples treated with NaOH. The decrease in permanent charge after attack with HCl was due to vermiculite decomposition. The different behaviour of the pH-dependent charge was attributed to the structural changes which different treatments can give rise on the interlayer materials.