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Large-scale cattle farming currently accounts for only 30% of the industry in China, where significant variation in farm sizes and distributions poses challenges to sustainable manure management. Moreover, substantial gaps exist in research on the environmental impacts of manure treatment technologies across different farm scales. The environmental and economic performances of eight different cattle manure management techniques, including six aerobic, three anaerobic, and integrated methods, were evaluated for small, medium, and large cattle farms using life cycle assessment and life cycle cost methods. The results indicate that the black membrane biogas pool (BMBP) offers the best environmental and economic benefits, reducing the global warming potential (GWP) by 101.3% and enhancing the profit by at least 148.7 CNY per ton of dry cattle manure. Significant disparities in cattle farming scale and manure production across provinces necessitate region-specific policies. The GWP from national cattle manure management stands at about 1.3 million tons of CO2 equiv, with major inputs from Sichuan, Yunnan, and Inner Mongolia, comprising 25.2% of the total. Increasing the utilization rate of cattle manure from 80% to 90% by 2025 could reduce the GWP by 11.0%. Advancing the BMBP and shifting 5% of aerobic to anaerobic processes could reduce carbon emissions by 0.2 million tons of CO2 equiv and other pollutants by 1.1–23.4%. Therefore, enhancing anaerobic technology and boosting utilization rates promise more efficient and synergistic reductions in CO2 emissions and other pollutants.
Ji et al. (Wed,) studied this question.