Although nitrogen (N) fertilizer application plays an essential role in improving crop productivity, an inappropriate management can result in negative impacts on environment and human health. To break this dilemma, a 12-year field experiment (2008–2019) with five N application rates was conducted on the North China Plain (NCP) to evaluate the integrated impacts of optimizing N management (Opt. N, 160 kg N ha⁻¹ on average) on agronomic, environmental, health, and economic performances of summer maize production. Over the 12-year study, the Opt. N treatment achieved the maximal average grain yield (10.6 Mg ha⁻¹) and grain protein yield (793 kg ha⁻¹) among five N treatments. The life cycle assessment methodology was applied to determine the negative impacts on environmental and human health, and both of them increased with the N rate. Compared with the farmers’ conventional N rate (250 kg N ha⁻¹), the Opt. N treatment reduced acidification, eutrophication, global warming, and energy depletion potentials by 29%, 42%, 35%, and 18%, respectively, and reduced the health impact by 32% per Mg of grain yield or grain protein yield produced. Both the Opt. N and Opt. N*50–70% treatments resulted in high private profitability (2038 USD ha⁻¹), ecosystem economic benefit (1811 USD ha⁻¹), and integrated compensation benefit (17,548 USD ha⁻¹). This study demonstrates the potential benefits of long-term optimizing of N management to maintain high maize yields and grain quality, to reduce various environmental impacts and health impacts, and to enhance economic benefits. These benefits can be further enhanced when Opt. N was combined with advanced agronomic management practices. The results also suggest that reducing the optimal N rate from 160 to 145 kg N ha⁻¹ is achievable to further reduce the negative impacts while maintaining high crop productivity. In conclusion, optimizing the N management is essential to promote sustainable summer maize production on the NCP.

Nitrogen fertiliser is critical for increasing crop yields worldwide, but excessive use causes significant N losses in various forms and subsequent environmental issues, such as greenhouse gas (GHG) emissions. Establishing regional universal nitrogen strategy (RUNs) is indispensable for technology adoption, resource conservation, and pollution mitigation in crop production. This study aims to develop a regional universal nitrogen fertilizer strategy to address variations in N application effectiveness, balancing agricultural productivity with environmental and eco-economic benefits. We conducted a total of 48 site-year field experiments including no nitrogen application (Control), farmers' practice (FP), and the implementation of the RUNs with optimized nitrogen recommended formulas and one-off application method. The RUNs significantly increased yields by 5.9%, 12%, and 11% for grain, sweet, and silage maize, respectively, compared with FP. Further, RUNs reduced life-cycle potentials of global warming, soil acidification, water eutrophication, and energy depletion by 22-45%, 63-76%, 51-73%, and 46-67%, respectively. The RUNs increased economic benefits by 11%-58.2%, and net ecosystem-economic benefits by 11.3-77.5%, particularly through the reduction of nitrogen fertiliser and labour-associated agricultural and ecological costs. We propose that the RUNs reconciled crop yield, resource efficiency, environmental impacts, and ecosystem economic benefits, demonstrating a regional sustainable N strategy for global food security and resource conservation.

Investigating the interaction effect of nitrogen (N) management strategies and stay-green types of maize hybrids is essential for enhancing N use efficiency and developing N-efficient hybrids. A field experiment was conducted with five N management treatments (Control, Opt.N*70%, Opt.N, Opt.N*130%, and Con.N) and two stay-green types of maize hybrids (stay-green hybrids: DH605 and ZD958; moderate-green hybrids: XY335 and XY1266) to examine their interaction effects on maize yield, aboveground biomass, and N uptake and allocation. The highest grain yields for moderate stay-green and over stay-green maize hybrids were 12.8 Mg ha⁻¹ and 10.8 Mg ha⁻¹, respectively. Compared to over stay-green hybrids, moderate stay-green hybrids exhibited a significantly higher aboveground biomass and N uptake. Under an optimal N (Opt.N) treatment, moderate stay-green hybrids achieved a 15.8% higher grain yield than over stay-green hybrids. Under the Opt.N*130% treatment, moderate stay-green hybrids had the highest grain N concentration, averaging 13.1 g kg⁻¹. Nitrogen application enhanced N allocation to grains, resulting in a 3.1–7.7% increase in grain N content. Moderate stay-green hybrids with optimal N management exhibited a 1.9% higher grain N content compared to over stay-green hybrids, whereas their vegetative organs had a relatively lower N content except for the Opt.N*130% treatment. Selecting a suitable maize hybrid (e.g., moderate stay-green maturity hybrid, XY335) and optimizing N fertilizer management can enhance grain yield, grain N content, and enhance N absorption and utilization efficiency.