Displacing Exchangeable Potassium in Cation Exchange Determinations

The amounts of exchangeable K displaced by NH4, Na, and Li using methods adopted in cation exchange determinations were compared. Besides differences due to the effect of the geometric factor of the replacing ion, related to its size and hydration characteristics, the behaviour of clays of two groups of soils was consistently and significantly different. A critical assessment of the data suggests that there is a considerable diversity in the distribution and bonding energy of the K adsorption sites on the various clays.