The addition of sawdust reduced the emission of nitrous oxide in pig manure composting by altering the bacterial community structure and functions

Abstract

Although composting, a measure to dispose agricultural waste, is widely accepted and applied, specific knowledge of microbially driven effects on nitrous oxide (N₂O) emissions during composting remains limited. Here, we monitored the impact of sawdust on N₂O emissions during pig manure composting. The results suggested that adding sawdust to the compost improved the compost temperature and reduced N₂O emissions. The addition of sawdust significantly altered the bacterial community structure and enhanced community turnover during the composting process. The addition of sawdust significantly reduced the relative abundance of denitrification and ureolysis, while increasing the relative abundance of nitrogen fixation. Specifically, adding sawdust may reduce N₂O emissions by reducing the relative abundance of Salinithrix, Truepera, Azomonas, Iamia, Silanimonas, Phycisphaera, and Gp21 during the thermophilic and mature phases of the composting period.