STUDIES ON SOIL POTASSIUM

Abstract

Summary The activity ratio a K /√(a Ca ±Mg) had the same value for all solutions in equilibrium with a chosen soil, regardless of their concentration (up to 0.06 M), or of the proportion of Ca to Mg. The activity ratio may be expected to provide a satisfactory measure of the ruling chemical potential of labile K in a soil, provided it is not used to compare soils of widely different Ca (and Mg) status, or a few soils of which the activity ratio is not independent of the concentration of the soil solution.