Optimizing N Management Enhances Interspecific Complementation in Maize-Pea Intercropping.

Cereal-legume intercropping has been identified as an effective system for increasing crop productivity and improving water and nutrient use efficiencies. However, little research has been reported how the two intercrops may share or compete for resources during their co-growth period under resource-limiting environments. Here, we quantified the competitiveness of the two intercrops in response to soil available N during their co-growth period, and determined the complementary effect of the early-harvest crop to the remaining crop grown in the alternate strips. A long-season maize (Zea mays L. ) was alternated in strips with a short-season pea (Pisum sativum L.) 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, enhanced crop yields significantly. Compared with the zero-N control treatment, N application increased the competitiveness of the intercropped maize to pea by 18 to 33% during the co-growth period. After pea harvest, the intercropped maize obtained a complementary effect from the pea strips, as reflected by the increased maize growth rate by 20, 21, 11, and 17%, respectively, under N0, N1, N2, and N3 managements, compared with monoculture maize. The total yield of the intercropping system is a quadratic relationship with the interspecies competitiveness, with the competitiveness value of –0.059 to –0.076 being most conducive to the improved crop yield. A strategy of applying 20% of the total N at maize jointing, 50% at pretasseling, and the remaining N topdressed post-flowering provided greatest benefits for optimizing the competitiveness of the two intercrops while enhancing the complementary effect in cereal-legume intercropping systems.