November 12, 2024 | Nature Food | Source |
Introduction: While nitrogen (N) inputs are essential for crop productivity, N losses from croplands contribute to major environmental issues, including climate change, air pollution, and water eutrophication. The effectiveness of N management in reducing these losses depends on both site-specific factors—such as land use, climate, and soil properties—and tailored field practices in nutrient, crop, and soil management. An international research team led by China Agricultural University and Wageningen University conducted a meta-analysis of 1,065 studies with 6,753 observation pairs to quantify the impact of optimized agricultural practices on N losses to air (Nâ‚‚O and NH₃ emissions) and water (run-off and leaching) while accounting for site-specific conditions.
Key findings: Optimized N management practices significantly reduced losses, with reductions of 3–39% for Nâ‚‚O emissions, 16–68% for NH₃ emissions, 21–37% for N run-off, and 19–52% for N leaching. Among these, enhanced efficiency fertilizers (e.g., controlled-release fertilizers, slow-release fertilizers) were the most effective, reducing all N losses by 28–35%, while optimized fertilizer application rates further improved efficiency. Other strategies, including organic fertilizers, biochar, and 4R-based fertilizer strategies (applying the right fertilizer rate, type, timing, and placement), reduced losses by up to 68%.
Regression analysis revealed that site conditions and crop type strongly influenced N losses, with nutrient management proving more effective than crop or soil management. Furthermore, trade-offs existed: while crop management reduced N leaching, it increased N₂O emissions, and zero tillage tripled NH₃ emissions due to limited incorporation techniques. After adjusting for local conditions and existing agricultural practices, estimated global reductions were 31% for N₂O, 23% for NH₃, 18% for N run-off, and 17% for N leaching.
These findings underscore the importance of integrated strategies to balance trade-offs and maximize nitrogen loss reduction. They also highlight the need for region-specific management strategies to maintain agricultural productivity while ensuring environmental sustainability. Future research should focus on refining site-specific models, addressing trade-offs, and developing robust upscaling approaches for more precise global impact assessments.
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Figure | Predicted impacts of optimal management practices on nitrogen losses in global croplands.
a–d, Predicted spatial variation in the impacts of combined optimal management practices on the relative average changes in N2O emissions (a), NH3 emissions (b), N run-off (c) and N leaching (d) in global croplands.
