EFFECT OF EXCHANGEABLE POTASSIUM ON THE HYDRAULIC CONDUCTIVITY AND INFILTRATION RATE OF SOME SOUTH AFRICAN SOILS

Abstract

We studied the effect of exchangeable K on the hydraulic conductivity (HC) and infiltration rate (IR) of three South African soils and compared it to the effects of exchangeable Ca and Na, using K-Ca and Na-Ca systems with different level of exchangeable K or Na. Increasing the amount of K in the exchangeable phase resulted in a decrease in both the HC and IR of the soils. It was found that, relative to Ca and Na, exchangeable K had an intermediate effect on the HC and IR of the soils. These observations support previous findings in-sofar as HC measurements are concerned and confirm the view that exchangeable K cannot be grouped together with either Ca or Na as ions having similar effects on the hydraulic properties of soils.