Sewage-sludge-derived biostimulant enables fertilizer reduction while maintaining rice yield through...

Modern agriculture relies heavily on chemical fertilizers to sustain high yields, yet excessive inputs contribute to soil acidification, water eutrophication, greenhouse gas emissions, and biodiversity loss. Sewage-sludge-derived biostimulants (SS-BS) may help reduce fertilizer dependency while sustaining crop performance through plant-soil-microbiome interactions. Here, we evaluated SS-BS in a paddy rice field trial conducted during a single growing season (2024) under conventional management. Three fertilization regimes were compared: low-fertilizer control (CK), conventional fertilization (FP), and reduced mineral fertilization supplemented with SS-BS (BS). Across the 2024 season, rice yield and key yield components in BS were comparable to, or approached, those in FP with reduced mineral fertilizer input. Shotgun metagenomic profiling indicated that BS was associated with shifts in microbial functional pathways related to nitrogen, phosphorus, and potassium cycling, and with changes in the relative abundance of taxa linked to nutrient transformation processes. Partial least squares path modeling (PLS-PM) further suggested that microbial functional attributes were associated with the relationships among fertilization regime, soil properties, and yield outcomes. Collectively, these results from a single-season field experiment indicate that SS-BS has the potential to support fertilizer-reduction strategies in rice systems and motivate multi-season validation of its agronomic performance and microbiome-associated effects.