Vermiwash as microbial inoculant improved compost quality and functional microbial succession in chicken manure composting.

Chicken manure composting faces challenges of slow maturation and nutrient losses. This study evaluated vermiwash bioaugmentation applied at 1.5% v/w to the composting substrate; the vermiwash was derived from Eudrilus eugeniae cultivated on an 8:2 cow-to-chicken manure substrate (20% chicken manure in the earthworm cultivation medium) selected for optimal vermiwash production. Vermiwash treatment achieved substantial improvements in nutrient content (nitrogen: 4.66% vs. 1.86%; phosphorus: 0.737% vs. 0.281%; free amino acids: 4.04 vs. 1.12 mg/g), microbial activity (density: 9.0 × 10⁹ vs. 1.3 × 10⁹ CFU/g), and maturity indicators (germination index: 100% vs. 58%; carbon mineralization: 25.5% greater). Comprehensive 16 S rRNA sequencing revealed distinct microbial succession from thermophilic Firmicutes (25-70%) to oligotrophic Bacteroidota and Proteobacteria (40% combined) at maturation, with enrichment of specialized degraders including Nocardiopsis (20% vs. 7%). Functional analysis (PICRUSt2) identified 73 differentially abundant pathways regulating membrane transport (17.8%), cellular signaling (11.0%), and core metabolism (26.0%). Vermiwash bioaugmentation provides a sustainable solution for converting agricultural waste into premium organic fertilizer with accelerated maturation (31 vs. 42 days) and superior nutrient retention, supporting reduced chemical fertilizer dependency in agriculture.