Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu

Abstract Fly ash, a by-product, contains a rich array of minerals and has demonstrated potential as a soil amendment. However, its synergistic interaction with organic and microbial inputs for improving crop productivity, particularly in silicate-deficient soils, remains insufficiently characterized. The present investigation was conducted during the Rabi season of 2024–2025 at Melpuliyankudi village, Cuddalore District, Tamil Nadu, with the objective of evaluating the integrated effects of fly ash, farmyard manure (FYM), green manure (GM), and silicate solubilizing bacteria (SSB) on rice yield and soil fertility. The experiment was laid out in a randomized block design (RBD) comprising thirteen treatments with three replications on sandy clay loam soils characterized by low organic carbon and deficient macronutrient status. Among the treatments, the integrated application of Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB significantly outperformed others, recording the highest grain yield (6623 kg ha⁻¹) and straw yield (8005 kg ha⁻¹), along with enhanced uptake of nitrogen (N), phosphorus (P), potassium (K), and silicon (Si). Post-harvest soil analysis revealed substantial improvements in available nutrient status under integrated nutrient management regimes. The findings underscore the potential of leveraging industrial by-products in combination with biological and organic amendments to sustainably enhance rice productivity and soil health. Further long-term studies across diverse agro-ecological zones are warranted to validate these outcomes and formulate region-specific nutrient management strategies.