Characterization and standardization of novel biochar granule formulation for enhancing silicon content and mitigating pest infestation in traditional rice varieties

Among the granular formulations evaluated, T 2 – Biochar: Rice husk ash: Lignite fly ash (BC: RHA: LFA) exhibited optimal physicochemical properties with neutral pH (7.29 ± 0.02), high porosity (62.69 ± 1.54 %), excellent flowability (1.29 ± 0.03 s) with enhanced macro and micronutrient content. The Scanning Electron Microscopy – Energy Dispersive X ray Spectroscopy (SEM – EDAX) analysis elucidated the presence of heterogeneous composite surface morphology with strong inter particle adhesion and effective integration of individual amendments with the predominance of C (56.37 wt %), O (25.48 wt %) and Si (16.07 wt %). FTIR spectrum unveiled the presence of key functional groups, C=C, -CH 2 , C = O, Si– O – Si, Si - O, Al-O in the biochar granules. The particle size analysis confirmed that T 2 had the most uniform distribution with Z-average: 559 nm, PDI: 0.35 and zeta potential of −25.7 mV. Microplot experiment conducted to standardize the granules against insect pests of three traditional rice varieties proved that the treatment, T 2 D 5 ( T 2 - BC: RHA: LFA, D 5 - 500 kg/ha) significantly reduced leaf folder in the order: Karunkuruvai (1.19 %) < Poongar (2.31 %) < Improved Kavuni (5.50 %). White ear incidence due to stem borer was much less in the order: Karunkuruvai (0.82 %) < Improved Kavuni CO 57 (1.12 %) < Poongar (2.07 %). The principal component analysis described strong associations between higher dosages of granular formulation with improved plant biometric and yield parameters. • The biochar granule formulation T 2 (BC: RHA: LFA - 1:2:1) exhibited superior physicochemical properties. • Elemental and structural analyses of biochar granules confirmed significant surface morphology, functional group diversity with silicon enrichment. • Application of T 2 D 5 ( D 5 - 500 kg/ha) significantly reduced stem borer and leaf folder in traditional rice varieties. • Among tested varieties, Karunkuruvai showed the highest silicon accumulation and efficient translocation from straw to grain. • Principal Component Analysis revealed enhanced vegetative growth and yield parameters highlighting the role of biochar granule in boosting crop productivity.