Abstract: 【Objective】To investigate the effects of nitrogen fertilizer management on the photosynthetic characteristics and yield of foxtail millet under ridge-furrow cropping in the semi-arid hilly region of the Yanshan Mountains,providing a reference for efficient fertilization strategies in foxtail millet cultivation in this area.【Methods】A two-factor field experiment was conducted in Songshan District and Ongniud Banner of Chifeng City,Inner Mongolia,from 2023 to 2024 to investigate the effects of five fertilization methods：no nitrogen fertilizer（F0）,one nitrogen application（pre-sowing,F1）,two nitrogen applications（pre-sowing and jointing stage,F2）,three nitrogen applications（pre-sowing,jointing stage,and heading stage,F3）,and four nitrogen applications（pre-sowing,jointing stage,heading stage,and flowering stage,F4） on photosynthetic indices,agronomic traits,and yield of foxtail millet under ridge-furrow cropping（D） and flat cropping（N） patterns,and to analyze the sources of nitrogen fertilizer contributions to yield increase under ridge-furrow cropping pattern. 【Results】Compared with the F0 treatment,the F3 treatment under the ridge-furrow cropping pattern increased the SPAD value and net photosynthetic rate of flag leaves in the late growth stage of foxtail millet;under both cropping patterns,the F3 and F4 treatments increased the flag leaves stomatal conductance（G_s）,intercellular CO₂ concentration（C_i）,and transpiration rate（T_r）,and improved the photosynthetic capacity of foxtail millet in the late growth stage. In 2023,the F3 treatment under the ridge-furrow cropping pattern increased the plant height,stem diameter,and panicle length of foxtail millet;in 2024,compared with the flat cropping pattern,the F3 treatment under the ridge-furrow cropping pattern increased the plant height,stem diameter,panicle length,and panicle diameter of foxtail millet by 0.54%,10.78%,1.21%,and 5.15%,respectively. During the two years,the F3 treatment showed the highest contribution rate of nitrogen application to yield,which was 22.12% and 39.29% respectively;the contribution rate of cropping pattern showed no significant differences among the fertilization treatments（P>0.05）,and the contribution rate of nitrogen management to foxtail millet yield increase was greater than that of cropping pattern. 【Conclusion】Under the ridge-furrow cropping pattern,three nitrogen applications（pre-sowing,jointing stage and heading stage） can better meet the nitrogen demand of foxtail millet in the late growth stages,enhance chlorophyll content and net photosynthetic rate at different growth stages,thereby increasing yield,and can serve as an optimal nitrogen fertilization strategy for high-yield foxtail millet production in the semi-arid hilly region of the Yanshan Mountains.

Key words: Nitrogen fertilizer management, Ridge-furrow cropping, Foxtail millet, Photosynthetic characteristics, Yield