Mitigation of NH3 and greenhouse gas emissions in chicken manure composting via housefly larvae pretreatment

The sustainable management of nitrogen-rich poultry manure is crucial for agricultural resource recovery, yet conventional aerobic composting often exacerbates nitrogen loss through substantial NH₃ and greenhouse gas (GHG) emissions. While insect-based bioconversion using housefly larvae (HL) presents a promising strategy to reduce nitrogen depletion, but incomplete organic decomposition remains a challenge. This study proposes a novel two-stage approach integrating HL pretreatment with aerobic composting to address these limitations. Compared with composting without HL pretreatment, the thermophilic period was significantly prolonged to 13 days, and germination index ( GI ) was significantly increased by 66.3%. Notably, NH 3 emission and global warming potentials of GHG were reduced by 50.3% and 17.8%, respectively, compared to CK without HL pretreatment. However, N 2 O emission was increased in HL treatment. Metagenomic analysis identified elevated ure abundance in CK promoted NH₃ release, whereas HL treatment enriched nirK gene, exhibiting a strong positive correlation with N₂O production ( P ＜0.05). Additionally, reduced nosZ abundance and elevated nosZ II/I ratio in HL groups further contributed to N₂O accumulation. These findings demonstrate the dual benefits of HL-composting in enhancing nitrogen retention and lowering NH₃ and GHG emissions, while highlighting the need to address N₂O mitigation. • Housefly larvae-composting can reduce NH 3 and CH 4 emissions from poultry manure storage. • Housefly larvae-composting corresponds to a 17.8% decrease in global warming potentials of greenhouse gases. • Emissions of N 2 O were greater under housefly larvae-composting. • Elevated NosZ II/I ratio linked to higher N 2 O emission in housefly larvae-composting.