Environmental, human health, and ecosystem economic performance of long-term optimizing nitrogen management for wheat production

Losses of nitrogen (N) fertilizers applied in the fields lead to adverse impacts on the environment quality, human and ecosystem health. Quantifying the integrated effects of N fertilizer on the environment, human health, and ecosystem economic benefits (EEB) is critical to developing sustainable N-management strategies. In this study, the life cycle assessment (LCA) and EEB evaluation of winter wheat under five N fertilizer levels for 12 years on the North China Plain (NCP) were performed. The LCA results demonstrated that, compared to the conventional N (Con. N) treatment, the optimal N treatment (Opt. N, 165 kg N ha⁻¹ on average) based on in-season root-zone N management, substantially reduced greenhouse gas emissions, acidification, eutrophication, and energy consumption potentials per Mg of grain produced by reducing life-cycle pollutants emissions. Moreover, the increase in crop yield in the Opt. N indirectly reduced the life-cycle land use, water use, human toxicity, aquatic ecotoxicity, and terrestrial ecotoxicity potentials per Mg of grain produced compared to lower N application treatments. Consequently, Opt. N had the lowest aggregated environmental indicator (0.39 EcoX Mg⁻¹). Also, Opt. N reduced the negative effects on human health by 28% and 31% compared to the without N treatment (CK) and Con. N treatments. In addition, the average N-derived EEB considering the cost from N fertilizer, ecosystem and human health effects was highest with Opt. N (1493 $ ha⁻¹). This study demonstrates that long-term optimal N management in wheat production can increase ecosystem economic benefits while reducing harm to the ecosystem and human health, and the integrated assessment of this study could provide a more comprehensive view on sustainable N management strategy to the policy-makers and stake-holders.