Potassium in shrink-swell soils of India: an enigma

Abstract

This paper critically reviews the information regarding the potassium (K) status of Indian soils based on research work conducted since 1929. The pattern and lacunaes of potassium consumption in India is also potrayed in this paper. The role of minerals in potassium availability viv-a-vis forms of potassium are discussed and elucidated with suitable clay mineralogical evidences. This publication also highlights the enigma of potassium availability to plants in Indian shrink-swell soils. Authors pointed out the inefficacy of the universal method used for assessing plant available K (1N NH4OAc) in Indian shrink-swell soil as observed from extensive K response studies. The current practices of assessing only plant available K is not adequate to detect native changes in soil potassium. This paradoxical situation necessitates the revision and revalidation of the existing potassium fertilizer recommendations, which are being adopted since four decades. A demand driven research articulating soil test crop response studies supported by mineralogical know-how at the back hand will help revising potassium evaluation methods in India ultimately benefiting the farmers and maintaining soil health