Response of Sulphur Sources on Dynamics of Nutrient Uptake and Soil Nutrient Status of Soybean (Glycine max (L.) Merrill) under Eastern Dry Zone of Karnataka, India

Background: Sulphur availability influences nutrient accumulation in soybean, but comparative evidence on dispersible granules, powder and bentonite pastilles in the Eastern Dry Zone of Karnataka remains limited. Objective: This study evaluated the effects of sulphur formulations and application rates on nutrient content, uptake and post-harvest soil nutrient status. Study Design: A randomised block design with eight treatments. Place and duration of study: A field experiment was conducted at the Agroforestry Unit, Zonal Agricultural Research Station, UAS, GKVK, Bengaluru, during kharif-2022 and 2023. Methodology: The treatments were T1: RDF + Sulphur 90% Dispersible Granules @ 12.5 kg ha-1, T2: RDF + Sulphur 90% Dispersible Granules @ 18.5 kg ha-1, T3: RDF + Sulphur 90% Dispersible Granules @ 25 kg ha-1, T4: RDF + Sulphur 90% Powder @ 18.75 kg ha-1, T5: RDF + Sulphur 90% Granular Bentonite Pastille @ 20 kg ha-1, T6: RDF + Sulphur 90% Granular Bentonite Pastille @ 30 kg ha-1, T7: University recommendation (RDF + zinc sulphate @ 12.5 kg ha-1), T8: Absolute Control. All sulphur sources were applied basally along with RDF (25:62.5:25 N: P₂O₅: K₂O kg ha-1). Results: Application of 90% sulphur at 25 kg ha-1 through dispersible granules along with RDF resulted in higher nutrient content and uptake in soybean grain and haulm. Post-harvest available nitrogen and sulphur were higher under T3 than under T8. Conclusion: Balanced nutrition of NPK and dispersible granular sulphur, which quickly disperses into finely divided particles, increases nutrient release and uptake by the soybean crop, leading to higher uptake and available soil nutrient content.