Effects of Previous Nitrogen Fertilizer Application on Yield and Nitrogen Use Efficiency of Wheat / Maize in the Next Season

【Objective】To elucidate the legacy effects of nitrogen fertilization in preceding crops on annual productivity and nutrient cycling patterns within winter wheat-summer maize system, aiming to develop precision fertilization frameworks that reconcile high crop yields with environmental sustainability in intensive cropping systems.【Method】Four fertilization regimes were established: long-term unfertilized control (T1), winter wheat-season fertilization only (T2), summer maize-season fertilization only (T3), and whole-year fertilization (T4). All fertilized treatments received identical nutrient inputs per growing season (N 150 kg/hm2, P2O5 150 kg/hm2, K2O 37.5 kg/hm2). The experiment followed a randomized complete block design with four replications, each treatment area was 64 m2. By measuring the effects of different fertilization treatments on nitrogen use efficiency and annual yield of next crop, the effect of single-season fertilization was analyzed.【Result】Field experiments demonstrated distinct treatment effects on crop performance across annual rotation cycles. Compared with T3, T2 treatment increased winter wheat yield by 11%, resulting in significant annual productivity enhancement. While no significant difference in dry matter accumulation was observed between T2 and T3 treatments during maize season, T2 exhibited a 15% advantage over T3 in winter wheat season. At summer maize tasseling stage (VT) and milky stage (R3), T2 showed 3% and 6% lower leaf area index (LAI) than T3, respectively, with corresponding 6% and 5% lower SPAD values in functional leaves. Notably, compared with T2, T3 displayed significantly higher net photosynthetic rate (Pn) and stomatal conductance (Gs) at big flare stage (V12), but this difference narrowed to 4.4% by R3. Although T2 and T3 treatments had no significant effect on the nitrogen accumulation of subsequent crops, the annual nitrogen partial factor productivity, nitrogen agronomic efficiency and annual nitrogen physiological efficiency of T2 treatment were 15%, 49% and 50% higher than those of T3 treatment, respectively, and the annual nitrogen recovery efficiency was higher.【Conclusion】In the winter wheat-summer maize system, fertilization in winter wheat season can maximize the residual effect of nitrogen fertilizer, provide better soil nitrogen conditions for the next crop, reduce the nitrogen fertilizer input of the next crop, and significantly improve the annual physiological efficiency of nitrogen fertilizer.