Overfertilization has led to extensive nitrate-N accumulation in deep soil profiles, thereby compromising the sustainability of dryland wheat cropping systems on China's Loess Plateau. Emerging evidence from long-term agroecosystem studies suggests that sustained management can drive soil-crop systems toward a dynamic equilibrium where nutrient pools stabilize. Based on this, we hypothesize that long-term optimized N management can drive the soil-crop system toward a dynamic equilibrium that balances high yield, high N use efficiency (NUE), and minimal nitrate-N accumulation. We tested this hypothesis through an 8-year and five-site field experiment, which quantified the equilibrium states of yield, NUE, and soil nitrate-N under the long-term performance of targeted fertilization (TF) and farmers' practice (FP). Then we developed a nitrate-based N recommendation model from equilibrium parameters. Results showed that, after the fourth year of TF, wheat yield and NUE stabilized at 6884 kg ha(-1) and 86%, while nitrate-N accumulation in the 0-1 m soil layer stabilized at 79 kg N ha(-1), with no significant temporal trend thereafter (P > 0.05), indicating the establishment of a stable equilibrium. In contrast, under FP, nitrate-N accumulation in the 0-1 m soil layer was 153 kg N ha(-1), with an annual increase of 5.4 +/- 1.2 kg N ha(-1) yr(-1). Across all sites, the peaks of nitrate-N accumulation in each 20 cm layer (71-107 kg N ha(-1)) under FP were observed at soil depths of 2.4-5.2 m. Compared with FP, TF reduced N surplus by 74%, nitrate-N accumulation in the 0-6 m soil profile by 57%, and greenhouse gas emissions by 25%. A Stable Targeted Fertilization (STF) model was developed using post-equilibrium nitrate-N to simplify N management. As a sequential approach that follows the TF regime after system stabilization, STF requires only a single post-harvest measurement during the stable phase to guide fertilization. Our study characterizes long-term N dynamics under contrasting N management in the dryland wheat production region and highlights the importance of incorporating legacy nitrate-N in the 0-1 m soil layer into fertilization management.