Potassium and Aluminium Dynamics in Acidic Soils under Different Rates of Lime Application

A pot-culture experiment was conducted raising rice (variety IET-4094) on limed soil [at 0, 0.5 and 1.0 lime requirement (LR)] from Kalimpong (Typic Haplumbrept) and Matimahal (Typic Paleustalf) in order to study the crop response to applied potassium (K) under different lime levels. The pH of both the treated soils increased sharply with increasing lime levels. All the forms of soil potassium, namely water soluble, exchangeable, non-exchangeable K and step-K decreased with increasing lime levels, except CR-K which remained nearly constant at all the levels of lime. Different forms of soil aluminium (AI), namely exchangeable, extractable and organically bound Al (except the crystalline Al which showed rather inconsistent trend on liming) decreased with liming except the amorphous AI. which increased somewhat on liming. A decrease in the dry-matter weight of rice as well as K-uptake by it was observed with increasing lime level. These findings were interpreted in terms of entrapment of soil K by the various forms of AI, removed/neutralized/precipitated upon liming the given acidic soils.