Objective Optimizing nitrogen management can stabilize crop yield, enhance nutrient use efficiency, and reduce carbon emissions. However, systematic investigations on the dynamics of nitrogen use efficiency, nitrogen balance, and carbon emissions under optimized nitrogen fertilizer management practices remain limited.

Methods A field experiment was conducted in Yuanyang County, Henan Province, on typical fluvo-aquic soil in the North China Plain using winter wheat as the test crop. Four treatments were established: no nitrogen fertilizer (CK), farmer practice fertilization (FP), optimized fertilization (NE), and combined organic-inorganic fertilization (MNPK) The effects of different nitrogen management strategies on winter wheat yield, nutrient use efficiency, soil nitrogen balance and carbon footprint were evaluated during 2024- 2025.

Results Compared with the FP treatment, the NE and MNPK treatments significantly increased the 2 years average winter wheat yield by 258.8 kg/hm² and 1388.3 kg/hm², representing increases of 2.6% and 14.1%, respectively(P<0.05). The NE treatment increased the average economic benefit by 847.5 yuan/hm² (a rise of 3.8%), whereas the MNPK treatment reduced it by 10584.9 yuan/hm² (a reduction of 47.3%). Compared with the FP treatment, over the 2 years average nitrogen recovery efficiency under the NE and MNPK treatments significantly increased to 27.8% and 36.9%, respectively(P<0.05). Agronomic efficiency significantly increased by 52.6% and 137.0%, and partial factor productivity significantly increased by 46.6% and 97.9%, respectively. The DNDC simulation results indicated taht the MNPK treatment exhibits the significantly lowest Net global warming potential (Net GWP) among all treatments. Compared to the FP and NE treatments, the MNPK treatment decreased the 2 year average Net GWP by 86.5% and 68.5%, respectively, and reduced the carbon footprint (CF) by 43.1% and 18.1%, respectively.

Conclusions In winter wheat production in the Huang-Huai-Hai Plain, optimized nitrogen management in chemical fertilizers when combined with organic fertilizers can improve nitrogen use efficiency, and reduce carbon emissions. Therefore, to further promote the combined application of organic and chemical fertilizers, it is necessary to reduce the cost of organic fertilizer and increase the economic returns on crops, thereby promoting sustainable farmland use.