Boosting system productivity through the improved coordination of interspecific competition in maize/pea strip intercropping
Abstract Intercropping has been considered to be an effective approach for producing large quantities of grain per unit of land. Maize (Zea mays L./pea (Pisum sativum L. strip intercropping may serve as a model for effectively boosting a system's productivity. However, how intercropped pea may compete for soil N sources with intercropped maize under various levels of N availability is unknown. Here, we determined the level of interspecific competition during the pea/maize cogrowth period, N2 fixation of pea, complementary growth effect on maize, and yield responses of the two component crops. The field experiment was conducted at Wuwei Experimental Station in northwestern China from 2012 to 2014. Different N management practices were implemented in the pea/maize systems. Intercropped pea was the dominant plant, as shown by the highly positive competitive ratio (averaging 1.35) and its aggressivity (averaging 0.31) values compared with intercropped maize. Ameliorating N application in the maize/pea strip intercropping intensified the interspecific competition, improved the N2 fixation of intercropped pea and increased the complementary growth of intercropped maize. On average, the N management system with 45 kg N ha 1 applied as the first topdressing plus 135 kg N ha 1 as the third topdressing increased the competitive ratio and aggressivity by 8% and 32% respectively; improved N2 fixation of the pea by 39% enhanced the complementary growth of maize by 10% and boosted the grain yield by 13% (maize) and 6% (pea) compared to the N management system with 135 kg N ha 1 as the first and 45 kg N ha 1 as the third topdressing. Significant positive correlations were found among the interspecific competition, N2 fixation, and grain yield, clearly showing that improved coordination of interspecific competition can boost system productivity in maize/pea strip intercropping.