Biochar Effectively Reduced N2O Emissions During Heap Composting and NH3 Emissions During Aerobic Composting

The composting process generates considerable amounts of greenhouse gases, presenting challenges for environmental protection. The utilization of biochar not only improves the composting efficiency but also reduces nitrogen (N) loss during composting. This study aimed to examine the impacts of adding biochar on the composting process, gaseous N emissions, and the bacterial community, as well as to clarify the difference between anoxic and aerobic composting. The experiment was conducted with cow dung and corn straw, with four treatments over 45 days: heap composting (C1), heap composting with 10% biochar (BC1), aerobic composting (C2), and aerobic composting with 10% biochar (BC2). The findings showed that adding biochar significantly reduced N2O emissions during the heap composting, achieving a cumulative emission reduction of 49.51% compared with composting without biochar. Meanwhile, aerobic composting led to a greater decrease in NH3 emissions, with a cumulative emission reduction of 56.56%. Additionally, there was a marked increase in the abundance of Bacteroidota and Chryseoline. Biochar reduced nitrogen losses, especially N2O emissions during heap composting and NH3 emissions during aerobic composting.