Interaction of climate and nitrogen fertilizer use on wheat yield and optimization strategies in China

Climate extremes, such as rising temperatures, pose severe threats to wheat yields. While appropriate nitrogen fertilization can mitigate these adverse effects, the optimal strategies for nitrogen application under changing climatic conditions remain poorly understood. Here, we used long-term nitrogen fertilizer application, climate, and wheat yield datasets covering wheat-growing regions in China during 1954–2020 and employed a fixed-effects panel model to quantify the effects of nitrogen fertilizer application on wheat yield. Additionally, we explored the adaptive effects of nitrogen application under climate risks. The results reveal that across all regions, climate trends contribute more to wheat yield variation than trends in nitrogen fertilizer use. Combined contributions of climate and nitrogen fertilizer use to wheat yield changes were −5.26%, −6.94%, and 1.31% in the Winter wheat (W R ), Spring wheat (SR), and Winter-spring wheat (W-SR) regions, respectively. In the W R and W-SR, increased nitrogen application intensified the adverse effects of high extreme-degree-days (EDD) on wheat yields but amplified the positive effects of higher growing-degree-days (GDD) and precipitation. In contrast, in the SR, optimal nitrogen fertilizer rates varied with EDD levels. Under warmer conditions, wheat yields decreased by 6.94% in the SR and 4.96% in the W R . Conversely, in the wetter and warmer W-SR, characterized by greater increases in rainfall and GDD, wheat yields rose by 3.57%. Under average climatic conditions, optimal nitrogen application rates were highest in the W-SR (168 kg N ha⁻¹), followed by the W R (163.47 kg N ha⁻¹) and the SR (65.93 kg N ha⁻¹). Our analysis demonstrates the interplay between climatic factors and nitrogen fertilization in determining wheat yield, shedding light on how varying climatic conditions influence nitrogen fertilizer use efficiency. The findings underscore the measurable interactions between nitrogen fertilization and climate, providing valuable insights for developing adaptive nitrogen management strategies under changing climatic conditions.