Observations on the determination of the availability of potassium for rhodes grass grown in open-cut mine overburden

Abstract

A potassium availability index, the value of the free energy of exchange of calcium and potassium, was determined when Rhodes grass growing in mine overburden and in topsoil exhibited visual potassium deficiency symptoms. The value was found to be -4060 ± 100 cal equiv.-1. There was no significant difference in this value between the overburdens and topsoil studied. The potassium characteristics of the growth media changed form during the growth of the Rhodes grass.