Objectives Post-anthesis drought and nutrient depletion are major constraints on yield formation in dryland wheat systems. Optimizing soil moisture conservation and fertilization strategies is therefore imperative for enhancing the synergistic efficiency of water and nitrogen utilization and improving grain yield.

Methods A field experiment was conducted from 2022 to 2024 at the dryland wheat experimental base in Wenxi, Shanxi Province, China. Treatments consisted of two tillage practices (no-tillage and deep plowing) combined with three nitrogen fertilizer application rates (135, 180, and 225 kg/hm²) under different precipitation year conditions. Post-anthesis soil moisture consumption, photosynthetic characteristics, nitrogen translocation and utilization, and yield of dryland wheat were systematically evaluated.

Results Compared with no-tillage, deep plowing during the fallow period significantly increased soil water storage in the 0−200 cm layer at anthesis, with increases of 4.43−8.39 mm in wet years and 10.74−28.63 mm in dry years, mainly attributable to enhanced water storage in the deep layer (100−200 cm) . Compared to no tillage, deep plowing promoted post-anthesis soil water consumption toward deeper layers. In wet years, deep plowing combined with 225 kg/hm² nitrogen fertilizer compared to other nitrogen fertilizer treatments, increased post-anthesis water consumption by 11.35 mm, whereas in dry years, deep plowing combined with 135 kg/hm² nitrogen fertilizer compared to other nitrogen fertilizer treatments increased water consumption by 36.33−43.48 mm. Compared to no tillage, deep plowing during the fallow period significantly increased the peak activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase (RCA) in flag leaves at 25 days after anthesis. Correspondingly the post-anthesis net photosynthetic rate increased in wet years under deep plowing combined with nitrogen fertilizer of 225 kg/hm² and in dry years under deep plowing or no tillage combined with nitrogen fertilizer of 135 kg/hm². Moreover, compared to no tillage, deep plowing during the fallow period increased pre-anthesis nitrogen translocation and in synergy with increased post-anthesis deep-layer water consumption, promoted nitrogen accumulation. Compared with other treatments, the treatment of 135 kg/hm² nitrogen fertilizer in dry year, increased post-anthesis nitrogen accumulation 72.65%−89.03% and percentage points of 24.91−31.32. Yield and water-nitrogen use efficiency analyses showed that deep plowing during the fallow period significantly increased spike number perarea, grains per spike, and 1000-grain weight, thereby resulting in yield increases of 18.87%−22.63% in wet year and 9.74%−29.70% in dry year. In wet years, the 225 kg/hm² nitrogen fertilizer treatment achieved the highest yield of 8014.69 kg/hm² by increasing spike number perarea by 3.16%−12.25% and 1000-grain weight by 1.29%−5.17%, but reduced water and nitrogen use efficiency. In dry years, the 180 kg/hm² nitrogen fertilizer treatment obtained the highest yield of 6168.78 kg/hm² and improved water and nitrogen use efficiency, with no significant differences in yield and water use efficiency compared with the 135 kg/hm² treatment. Correlation analysis revealed significant positive relationship among post-anthesis Rubisco activity, stem nitrogen translocation, and deep-layer water consumption, which constituted the physiological basis for yield improvement.

Conclusions Deep plowing during the fallow period combined with appropriate nitrogen application rates (180−225 kg/hm² in wet years and 135−180 kg/hm² in dry years) facilitates precipitation storage in soil layers below 100 cm and its subsequent utilization after anthesis. This management strategy strengthens post-anthesis water and nitrogen use, improves photosynthetic performance and yield formation, and enhances the climate resilience of rain-fed agricultural ecosystems. these findings provide a theoretical basis for high-yield and high-efficiency cultivation of dryland wheat.