Abstract:
The c.e.c. of Na-Al- and Ca-Al-montmorillonites after neutralization with NaOH or Ca(OH)2 was studied. At low levels of Al (10-50% of the c.e.c.) the c.e.c. of montmorillonite at pH 7.5 was reduced due to hydroxy-Al precipitation. The c.e.c. of soils exposed to rainfall may be reduced due to clay dissolution and hydroxy-Al interlayer formation, thus changing clay dispersion and soil permeability. -R.A.H. Inst. of Soils & Water, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.