Characterisation of Potassium in Black Soils Developed on Different Parent Materials in Tungabhadra Catchment

The variation in K content and its distribution in the soil profile was not found to be related to difference in K content of the parent materials. On an average these soils contained 913 mg total K₂O/100g soil, of which 9.12% was HNO₃ soluble, 2.86% exchangeable, 0.94% citric acid soluble and 0.11% water soluble. No relationship seems to exist between total K content of the soil and other K fractions. However, HNO₃ soluble, exchangeable, citric acid soluble and water soluble K found to be intercorrelated, indicating the existance of a reversible equilibrium between different fractions of soil potassium. Positive and highly significant correlation was seen between exchangeable and citric acid soluble K and amount of silt, clay, organic matter content, pH and CEC, whereas water soluble K was found to be independent of these soil factors.