Objective  To explore the effect of sugarcane (Saccharum officinarum)-mungbean(Vigna radiata) intercropping and different nitrogen application levels on sugarcane growth, yield and nitrogen nutrition, and provide a reference for rational sugarcane intercropping.

Method  Three cropping patterns (monocropping of mungbean, monocropping of sugarcane, intercropping of sugarcane and mungbean with mungbean straw returning), and three nitrogen treatments (no N application, reduced N application, conventional N application) were used in the experiments. Sugarcane traits during different growth period were measured.

Result  Tiller number, dry biomass, nitrogen uptake, number of millable stalks and cane yield of sugarcane were significantly affected by nitrogen level and cropping pattern. Sugarcane emergency number was also significantly affected by cropping pattern. Number and percentage of millable stalks, dry biomass and nitrogen uptake of sugarcane were significantly affected by nitrogen level×cropping pattern. Compared with monocropping of sugarcane, intercropping treatment reduced emergency number and tiller nubmer by 9.61%−10.52% and 10.30%−11.05% respectively, while increased number of millable stalks, dry biomass, nitrogen uptake and cane yield of sugarcane by 0.15%−14.28%, 14.28%−34.76%, 24.00%−29.58% and 15.88%−20.16%, respectively. For the intercropping treatment, the land equivalent ratio was 1.47−1.53 after sugarcane grew for 80 days, and the land equivalent ratio at sugarcane harvest was 1.76−1.94. The competition ability of sugarcane was greater than that of mungbean. Compared with monocropping of sugarcane with conventional N application, intercropping treatment with reduced N application did not decrease cane yield and soil nitrogen level.

Conclusion  Intercropping of sugarcane and mungbean can increase the land equivalent ratio and soil nitrogen level, promote sugarcane growth and increase cane yield and nitrogen uptake.