Evidence of potassium fixation through mono and divalent ion exchange

Mono and divalent cation exchange in some algerian major soil types was studied following empirical ap· proach. The reaction 2 Na-Soil + Ca2+= Ca-Soil + 2 Na+did not show complete reversibility possibly due to high Ca selectivity of soils. The soils exhibited divalent over monovalent ion affinity but for monovalent ion exchange the affinity in few cases remained almost the same. Gapon's equation did not seem to describe Ca-K exchange very satisfactorily because exchangeable potassium ratio (EKR) and potassium adsorption ratio (KAR) are not related linearly. The latter seems to be due to potassium fixing ten· dency of soils investigated.