Herbaceous Peat Enhances Nitrogen Retention via Microbial Regulation in Chicken Manure Composting

All additives inhibited the expression of nitrogen-cycling functional genes, with OSP and HP showing greater suppression of nitrification genes (AOA-amoA, AOB-amoA), and LCC exerting the strongest inhibitory effect on denitrification genes (nirK, nosZⅠ). HP had the most complex bacterial co-occurrence network and balanced fungal interspecific competition and cooperation, while LCC enriched aerobic functional bacteria and OSP adapted to alkali-tolerant microorganisms.

The regulatory mechanisms of the three additives for nitrogen retention were distinct: LCC improved compost aeration to inhibit anaerobic denitrification; OSP regulated pH and adsorbed NH4+-N; and HP achieved stage-specific synergistic regulation of the nitrogen cycle through the dual advantages of humic components and a porous structure. This study clarifies the effects of nitrogen retention and microbial mechanisms of LCC, OSP, and HP in chicken manure composting, and provides theoretical insights and technical guidance for selecting and applying efficient, sustainable natural additives in livestock manure composting.