Potassium Solubilizer Induced Dynamics of Potassium in Varied Mineralogy and Available K Soils of Eastern Dry Zone of Karnataka, India

Abstract

Background: Potassium being a major nutrient in plant nutrition plays important role in activation of more than 60 enzymes in plants. Its availability is major constrain in different soils which mainly depends on minerology of the soil and form in which it is present Viz., Water-soluble (readily available), Exchangeable (readily available) and non-exchangeable (slowly available) these are very much available forms of potassium and the lattice/mineral form is very slowly available form of nutrient. Wherein, mineral has to weather and need to add to the soil available form but there exists the dynamic equilibrium between all these 4 forms of potassium. On other hand, potassium solubilizers has an ability to solubilizes the mineral K which helps in boosting potassium availability by converting insoluble mineral K to soluble K by releasing organic acids. Aim: To study the existence of dynamic equilibrium existing between the different forms of potassium with K- solubilizer and fertilizer application in different minerology and available K status of soils. Study Design: Completely randomised design with four treatment and 3 replications. Place and Duration: A pot culture experiment was conducted in green house at university of agricultural sciences, Bengaluru, Karnataka, India and soil were incubated for 15, 30, 60 and 120 days. Methodology: The study consists of 3 different soils with low, medium and high in available potassium content collected form Eastern dry zone of Karnataka. The samples were subjected to X-ray diffraction (XRD). Later, 4 treatments were induced Viz., control, Fertilizer-K, K-solubilizer and K-fertilizers + K solubilizers for each soil. The treatments were replicated thrice for each treatment and soils were kept for incubation studies by maintain moisture at field capacity and destructive soil sampling was done at 15, 30, 60 and 120 Days after incubation and were analysed for potassium fractions. Results: Application of K solubilizer to low, medium and high available K soils mainly in K-solubilizer treatment and fertilizer-K + K-solubilizers has led to release of non-exchangeable K into water-soluble and exchangeable with 37, 30 and 11.61 % increase in water soluble K over the initial value in low, medium and high K soils respectively in K-solubilizer treatment and 132 , 53.46  and 46.07  increase in water soluble K in low, medium and high K soils respectively, over the initial values in the Fertilizer K + K-solubilizer treatment. Exchangeable K was increased upto 7.05, 6.96 and 3.22 % over the initial K in K-solubilizer treatments in low, medium and high K soils respectively in K- solubilizer treatment and 15.22, 14.99 and 8.32 % increase in exchangeable K was recorded in Fertilizer-K + K-solubilizer treatment in low, medium and high K soils respectively. Both this forms water soluble and exchangeable are mainly bio available for the plant. On other hand there was concomitant decrease in non-exchangeable K with increase in water soluble and exchangeable K in the said treatments. Conclusion: application of K-solubilizers helps in brining non-exchangeable form of potassium into water soluble and exchangeable form thereby decreases the fixation of K in different mineralogy soils.