农业食品系统中的可持续氮管理_132页_7mb

Summary of Sustainable Nitrogen Management in Agrifood Systems

Core Content

This report, published by the Food and Agriculture Organization of the United Nations (FAO), provides a comprehensive analysis of nitrogen use and its challenges within agrifood systems. It highlights the importance of nitrogen as a fundamental element for life, emphasizing its role in agricultural productivity and the broader environmental and ecological consequences of its mismanagement. The report outlines strategies to improve nitrogen use efficiency (NUE) and promote sustainable nitrogen management, with a focus on both crop and livestock systems. It also explores the potential of circular bioeconomy approaches to enhance resource efficiency and reduce nitrogen losses. The document concludes with policy recommendations aimed at transforming agrifood systems to achieve sustainability goals.

Main Viewpoints

• Nitrogen's Role: Nitrogen is essential for life and forms the basis of amino acids and proteins. It is a critical component of agrifood systems, supporting both crop and livestock production.
• Human Impact on Nitrogen Cycle: The Haber-Bosch process has enabled the mass production of synthetic nitrogen fertilizers, significantly boosting crop yields. However, this has disrupted the natural nitrogen cycle, leading to environmental issues such as pollution, biodiversity loss, and climate change.
• Nitrogen Losses: Nitrogen is lost through emissions of ammonia (NH₃), nitrogen oxides (NOₓ), and nitrous oxide (N₂O), as well as nitrate (NO₃⁻) leaching. These losses harm air and water quality, contribute to eutrophication and acidification, and negatively impact ecosystems.
• Agrifood Systems as Key Contributors: Agrifood systems are major drivers of nitrogen imbalance, with the livestock sector being the primary source of nitrogen losses, accounting for about one-third of total anthropogenic nitrogen emissions.
• Regional Disparities in Nitrogen Management: Nitrogen management practices and policies vary significantly across regions. While some areas, such as the EU and North America, have achieved higher NUE through regulations and best practices, others, such as Asia and Latin America, face challenges due to overuse of synthetic fertilizers or limited access to them.
• Circular Bioeconomy as a Solution: The circular bioeconomy offers promising strategies to improve nitrogen use efficiency by recycling organic residues, reducing food loss and waste, and integrating crop and livestock systems.

Key Information

• Nitrogen Use Efficiency (NUE): Defined as the ratio of nitrogen recovered in the final output to the total nitrogen used as input. Improving NUE is essential for sustainable nitrogen management.
• Trends in NUE: There has been a general trend of increasing NUE over time, but many regions still lag behind, particularly low- and middle-income countries (LMICs).
• Challenges in LMICs: Limited access to synthetic fertilizers and inadequate policies lead to soil degradation and low crop yields. Organic fertilizers such as manure and compost can help mitigate these issues.
• Circular Bioeconomy Principles: These include reducing food loss and waste, recycling organic materials, and using arable land efficiently for direct human consumption. Livestock can also be used to convert waste into valuable resources.
• Policy Instruments: The report suggests that policies should aim to reduce nitrogen pollution, promote sustainable practices, and integrate nitrogen management into broader sustainability goals, such as the Sustainable Development Goals (SDGs) and the Paris Agreement.
• SDGs and Nitrogen Management: Sustainable nitrogen management is crucial for achieving several SDGs, including ending hunger (SDG 2), improving health (SDG 3), ensuring clean water (SDG 6), promoting sustainable production and consumption (SDG 12), taking climate action (SDG 13), and protecting life on land and in water (SDGs 14 and 15).

Key Recommendations

• Improve NUE in Cropping Systems: Encourage biological nitrogen fixation in suitable crop rotations and the use of manure as organic fertilizer. LMICs should enhance access to synthetic fertilizers and promote agroecological practices.
• Enhance Livestock Nitrogen Management: Develop guidelines for efficient manure handling and processing, integrate livestock with local crop production, and optimize feed formulations to reduce nitrogen excretion.
• Reduce Nitrogen Loss and Waste: Implement measures to minimize food loss and waste and promote the recycling of unsuitable food into livestock feed.
• Promote Public and Private Investment: Encourage investment in sustainable nitrogen management practices, including low-emission fertilizers and organic residue production.
• Strengthen Capacity Building: Support national and local stakeholders in adopting sustainable nitrogen practices through education, extension services, and field schools.
• Integrate Nitrogen Management into Policies: Include nitrogen management in nationally appropriate mitigation actions and climate commitments, such as the Paris Agreement, and align with the Kunming-Montreal Global Biodiversity Framework.

Conclusion

The report emphasizes the need for a holistic approach to nitrogen management in agrifood systems, highlighting the importance of balancing nitrogen use with environmental protection. It calls for collaborative efforts at all levels, from local to global, to address nitrogen challenges and promote sustainable practices that support food security, environmental health, and the well-being of communities. By adopting circular bioeconomy principles and improving nitrogen use efficiency, agrifood systems can contribute to achieving the SDGs and mitigating the triple planetary crisis of climate change, pollution, and biodiversity loss.