Meta-analysis of the effects of relay and double-cropping systems on weed control and crop production in arable lands

Relay and double cropping offer a pathway for ecological intensification by improving weed suppression and maintaining crop production. Although numerous studies have examined the effects of relay and double cropping on crop yield and weed management, a comprehensive synthesis is needed to summarize the overall impact. This research presents a meta-analysis investigating the effects of relay and double cropping on weed control traits and crop production outcomes. A total 49 international articles reporting relevant data were selected and analyzed. Both systems significantly suppressed weeds. Specifically, the relay cropping system reduced weed biomass by 78% and density by 64%, while the double cropping system led to reductions of 95% in biomass and 66% in density across diverse environmental conditions. While double cropping was more effective at reducing weed biomass, both systems had a non-significant impact on weed species richness. Ultimately, the choice of system involves a trade-off, as the superior weed suppression of double cropping came at the cost of a significant reduction in crop production (yield), whereas relay cropping did not significantly impact yield. Future research should refine relay cropping systems through site-specific management and crop breeding to optimize their role in sustainable agriculture.