Objectives This study aimed to investigate the yield differences caused by soil nitrogen fertility levels and the nitrogen fertilization across the main maize-producing areas of Huang-Huai-Hai Plain. These findings will provide a theoretical foundation and technical support for enhancing maize production and optimizing nitrogen fertilizer management.

Methods The literature that published from 2000 to 2024 were searched in databases such as CNKI, VIP, Wanfang, Web of Science and Google Scholar using the keywords Huang-Huai-Hai Plain, maize, nitrogen fertilizer, nitrogen application rate and yield. The maize yield under no nitrogen application was defined as the soil nitrogen fertility yield, and the soil nitrogen fertility levels were classified into four categories based on the maize yield levels: <6 t/hm², 6−8 t/hm², 8−10 t/hm² and >10 t /hm². The yield difference between fertilization and no fertilization of a field, yield increase rate of nitrogen fertilizer, the contribution of soil nitrogen fertility to yield and nitrogen fertilizer use efficiency were analyzed. The boundary line fitting method was employed to analyze the relationship between soil nitrogen fertility yield and nitrogen fertilization yield of maize, and the impact of soil nitrogen fertility levels on the gaps between predicted and actual yields. The effects of soil nitrogen fertility levels on the stability and sustainability of maize yields were evaluated.

Results Across Huang-Huai-Hai Plain, the soil nitrogen fertility yield, nitrogen fertilization yield, and yield increase rate of nitrogen fertilizer were averaged 8.07 t/hm², 10.06 t/hm², and 28.19%, respectively. The areas with soil nitrogen fertility yield <8 t/hm² accounted for 52.12% of the total sowing area. As soil nitrogen fertility levels increased from <6 t/hm² to >10 t/hm², the fertilization yield increased significantly from 8.37 t/hm² to 12.78 t/hm², while the yield increase rate decreased markedly from 58.03% to 14.41%.The contribution rates of soil nitrogen and nitrogen fertilizer to maize yield were 81.46% and 19.80% on average of 25-year period, respectively. The average partial factor productivity and agronomic efficiency of nitrogen fertilizer were 51.55 kg/kg and 9.93 kg/kg, respectively. The soil nitrogen fertility level did not significantly impact the partial factor productivity of nitrogen, while the nitrogen agronomic efficiencies showed a significant decline with the increasing of soil nitrogen fertility levels. Using the boundary line method, the predicted maximum yield of maize in the Huang-Huai-Hai plain was 15.20 t/hm². As soil nitrogen fertility levels increased from <6 t/hm² to >10 t/hm², the gap between the predicted and actual yields decreased from 6.88 t/hm² to 2.47 t/hm², the yield stability index decreased from 0.22 to 0.11, and the yield sustainability index increased from 0.53 to 0.71.

Conclusion In the Huang-Huai-Hai region, the proportion of soil nitrogen fertility yield below 8 t/hm² is as high as 52.12%. The yield gap of maize between the highest and lowest soil nitrogen fertility levels reaches 9.99 t/hm², while the yield difference caused by nitrogen fertilizer application is as high as 11.61 t/hm². The higher the soil nitrogen fertility level, the higher the contribution rate of soil nitrogen to maize yield, and the better the stability and sustainability of yield. Therefore, improving the basic soil nitrogen fertility level is a crucial measure to enhance the nutrient resource utilization efficiency of maize in the Huang-Huai-Hai region and achieve a win-win situation in both economic and environmental benefits.