The article "Agroecosystems, Nitrogen-use Efficiency, and Nitrogen Management" by Cassman, Dobermann, and Walters discusses the global challenge of meeting increased food demand while protecting environmental quality, focusing on nitrogen (N) management in cereal production systems. The authors emphasize the importance of synchronizing N supply with crop demand to optimize yield, profit, and environmental protection. They highlight the need for quantitative understanding of current N-use efficiency (NUE) and losses in these systems, as well as the economic returns from improved management practices. The paper examines NUE in cereal production systems, particularly maize, rice, and wheat, which provide over 60% of human dietary calories. NUE is defined as the proportion of N inputs that are removed in harvested crop biomass, recycled crop residues, and incorporated into soil organic and inorganic N pools. The authors note that experimental plots often overestimate NUE compared to farmers' fields due to differences in scale and management practices. Key findings include: - NUE can be increased by improving uptake efficiency from applied N inputs, reducing N losses from soil organic and inorganic N pools, or both. - The size of organic and inorganic N pools has reached steady-state or is changing slowly, making NUE dependent on RE_N (recovery efficiency of applied N). - On-farm measurements of RE_N are often lower than those from experimental plots, reflecting the challenges of managing N in real-world agricultural systems. - Improving RE_N requires innovative crop and soil management practices, such as precision management to maximize synchrony between N demand and supply. - The authors emphasize the need for research and policies that support the tripartite goals of food security, agricultural profitability, and environmental quality. - Effective policies should provide information on NUE components to farmers and support strong research and extension programs. The article concludes by highlighting the need for better understanding of NUE components and the potential for interactions between environmental goals, as well as the importance of incentive programs to promote N-efficient management practices.The article "Agroecosystems, Nitrogen-use Efficiency, and Nitrogen Management" by Cassman, Dobermann, and Walters discusses the global challenge of meeting increased food demand while protecting environmental quality, focusing on nitrogen (N) management in cereal production systems. The authors emphasize the importance of synchronizing N supply with crop demand to optimize yield, profit, and environmental protection. They highlight the need for quantitative understanding of current N-use efficiency (NUE) and losses in these systems, as well as the economic returns from improved management practices. The paper examines NUE in cereal production systems, particularly maize, rice, and wheat, which provide over 60% of human dietary calories. NUE is defined as the proportion of N inputs that are removed in harvested crop biomass, recycled crop residues, and incorporated into soil organic and inorganic N pools. The authors note that experimental plots often overestimate NUE compared to farmers' fields due to differences in scale and management practices. Key findings include: - NUE can be increased by improving uptake efficiency from applied N inputs, reducing N losses from soil organic and inorganic N pools, or both. - The size of organic and inorganic N pools has reached steady-state or is changing slowly, making NUE dependent on RE_N (recovery efficiency of applied N). - On-farm measurements of RE_N are often lower than those from experimental plots, reflecting the challenges of managing N in real-world agricultural systems. - Improving RE_N requires innovative crop and soil management practices, such as precision management to maximize synchrony between N demand and supply. - The authors emphasize the need for research and policies that support the tripartite goals of food security, agricultural profitability, and environmental quality. - Effective policies should provide information on NUE components to farmers and support strong research and extension programs. The article concludes by highlighting the need for better understanding of NUE components and the potential for interactions between environmental goals, as well as the importance of incentive programs to promote N-efficient management practices.