Multi-Scale Control Strategies for Nitrogen Loss During Aerobic Composting of Agricultural Waste: A Review

Aerobic composting is an important pathway for the resource utilization of agricultural waste. However, nitrogen loss during composting not only reduces the nutrient value of the final product but also causes environmental burdens, particularly through ammonia (NH3) volatilization and nitrous oxide (N2O) emissions. The objective of this review is to systematically summarize the sources, pathways, and mechanisms of nitrogen loss during aerobic composting of agricultural waste and to evaluate multi-scale control strategies for enhancing nitrogen retention and mitigating environmental emissions. This review addresses an important gap by integrating the sources, pathways, and mechanisms of nitrogen loss with practical mitigation strategies across the feedstock, in-process, post-treatment, system design, and macro scales. The synthesis indicates that the major nitrogen loss routes during aerobic composting include NH3 volatilization, N2O emissions, and nitrate leaching. From a multiscale perspective, the review synthesizes control strategies spanning feedstock pretreatment, including optimization of carbon-to-nitrogen (C/N) ratio, adsorbent amendment, and microbial inoculation; in-process regulation, including aeration, moisture, temperature, pH; and post-treatment approaches for nitrogen stabilization and resource recovery. The supporting roles of reactor innovation, intelligent process control, and policy and regulatory measures are also discussed. Finally, current bottlenecks and future research directions are summarized from environmental and economic perspectives, with particular emphasis on interdisciplinary integration and technological innovation to enhance nitrogen retention during composting.