Background and aims: Cereal-legume intercropping has signifcant advantages over the corresponding sole cropping patterns regarding efcient nitrogen utilization. However, a systematic theoretical and practical basis for improving the nitrogen use efciency (NUE) in intercropping systems by optimizing nitrogen management is still lacking.

Methods: The postponing N fertilizer topdressing on nitrogen interspecifc competition and complementary in pea/maize intercropping was investigated. At the jointing stage and 15-d post-silking stage of maize (N3), 108 and 36 kg N ha-1 were topdressing, respectively. During the jointing stage of N3, 72 kg N ha-1 and 36 kg N ha-1 were transferred to the 15-d post-silking stage, thus resulting in the N1 and N2 treatments.

Results: The postponed N fertilizer topdressing enhanced the N accumulation of crops. Compared with N3, N1 treatment increased the N accumulation of pea/maize intercropping and monoculture maize by 19.3% and 18.5%, respectively. The N1 improved the nitrogen interspecifc competition of intercropped pea and nitrogen recovery growth of intercropped maize. The N accumulation in the intercropping system is a quadratic relationship with the nitrogen interspecifc competition and a positive linear relationship with nitrogen recovery growth. Consequently, the grain yield and NUE of pea/maize intercropping with N1 increased by 27.3% and 78.8% compared to N3.

Conclusion The postponed N fertilizer topdressing, especially 72 kg N ha-1 from the jointing stage to 15-d post-silking stage, can synergistically regulate the nitrogen interspecifc competition of pea and the nitrogen recovery growth of maize.