Annual intercropping suppresses weeds: A meta-analysis

Intercropping has been advocated as an environmentally benign method to suppress weeds in agriculture. However, it is not evident from the literature what size of weed suppressive effect achieved on average by intercropping, and how species choice crop management affect this effect. We conducted a global meta-analysis published data quantify intercropping biomass annual arable intercrops grown for their final product. searched identify all papers reporting usable experimental extracted 339 records 39 publications containing 76 independent experiments. Two metrics suppression were defined assess intercropping: ratio observed intercrop less sole (Rweak), more (Rstrong). On average, was substantially significantly (58%) lower (Rweak = 0.42) than crop. No significant difference found between crop, even though tended be slightly larger (Rstrong 1.08). Findings consistent across different groups combinations, such maize/legume small-grain cereal/legume intercrops. Intercrops with additive design had stronger replacement design. In latter, mixed arrangement gave row design, while spatial did ability designs. effects simultaneous vs. relay nitrogen fertilizer input. The Rweak decreased land equivalent but intercrops, Rstrong unrelated LER both results confirm that generally useful approach suppressing cultivation. Further work needed disentangle contributions density, traits mixing intercropping.