Interspecific Competition and Complementation is a Function of N Management in Maize-Pea Intercropping Systems

Intercropping as an effective system for increasing crop yield. However, little is known about how the two intercrops compete for resources under resource-limiting environments. Here, we quantified the competitiveness of the intercrops in response to soil available N during their co-growth period, and determined the complementary effect of one intercrop to the other. A long-season maize was alternated in field strips with a short-season pea under four (N0, N1, N2, and N3) N management systems in northwestern China in 2012 and 2013. The maize-pea intercropping, coupled with N application, can enhance crop yield. Compared with N0 treatment, N application increased the competitiveness of intercropped maize to pea by 18 to 33% during the co-growth period. After pea harvest, the intercropped maize obtained a complementary effect, where it was grown under N0, N1, N2, and N3 managements increased the growth rate by 20, 21, 11, and 17%, respectively, compared with monoculture maize. The yield of intercropping system is a quadratic relationship with the interspecies competitiveness, with the competitiveness value of -0.059 to -0.076 being most conducive to improve the grain yield. We conclude that the treatment on 20% of the total amount of N top-dressed at maize jointing, 50% at pretasseling, and the remaining N topdressed 10 d postflowering provided the greatest benefits for minimizing intercrop competitiveness while enhancing the complementary effect among the four N managements investigated.