Interventions to Improve Potassium Availability in Light Textured Alfisols Supporting FCV Tobacco

Abstract

Aim: To investigate the effect of soil inversion in conjugation with combined application of SOP with cheaper potassium supplements like tobacco stalk biochar (TS biochar) and barn wood ash (BWA) on potassium fractions in light textured sandy loam soils supporting FCV tobacco. Study Design: Split plot design Place and Duration of Study: ICAR-CTRI RS, Jeelugumilli, Andhra Pradesh, India. Methodology: A field experiment was conducted with two main plots and seven sub-plots which are replicated thrice. The two main plots are consisting of soil inversion practices i.e., (i) soil inversion with MB plough (ii) without soil inversion and seven sub plot treatments viz., one without potassium, two sulphate of potash treatments at the rate of 100 % and 75 % of recommended dose of fertilizer (RDF), two TS Biochar treatments along with SOP and two BWA treatments along with SOP at the rate of 100 % and 75 % RDK each. Soil Samples were collected at 60 DAP to study various potassium fractions in the soil. Results: Results indicated that mean water-soluble potassium has been increased from 17.90 mg kg-1 in without soil inversion to 27.61 mg kg-1 in with soil inversion respectively and among the potassium input management practices highest mean water-soluble potassium of 26.60 mg kg-1 was observed in S4 [100% K through SOP + Tobacco Stalk Biochar (1:1)] treated plots which is on par with S2 [100% K through SOP]. An increase in soil mean exchangeable potassium from 40.07 mg kg-1 without soil inversion to 58.79 mg kg-1 with soil inversion was observed and among the potassium input management practices the highest available potassium was observed in S4 [100% K through SOP + Tobacco Stalk Biochar (1:1)] treated plots with a mean value of 60.14 mg kg-1 which was on par with S6 [100% K through SOP + Barn wood ash (1:1)]. Conclusion: Both soil inversion and potassium input management has improved the water soluble, exhangeable K in soil while no much influence on non-exchangeable and total K were observed.