Woody peat reduces nitrogen loss by influencing denitrifying bacteria and functional genes

This study aimed to explore the impacts of adding different proportions of woody peat (WP) on denitrification during composting. The results demonstrated that T1 and T2 increased the total Kjeldahl nitrogen content and reduced the nitrate nitrogen content after composting. After composting, the abundances of nirK and nirS decreased by and under T1 and T2, respectively. Adding WP reduced the abundances of key denitrifying bacteria such as Pseudomonas, Pusillimonas, Achromobacter, and Rhizobiales. The carbon content, nitrogen form (nitrite nitrogen and ammonium nitrogen), and denitrifying bacteria community were the main factors that affected denitrification genes. In summary, adding 15% WP has the best ability to reduce nitrogen loss by decreasing the abundances of denitrifying bacteria and denitrifying functional genes, thereby improving the agricultural value of composting products.