Sugarcane yield response to legume intercropped: A meta-analysis

Intercropping with legumes has attracted much attention worldwide, regarded as a sustainable alternative to chemical N-fertilizer. Many studies have investigated the effects of introducing legumes into sugarcane systems. However, how agro-environmental conditions influence the effect of legumes on sugarcane yield is still unclear. Thus, we performed a meta-analysis to (i) quantify the effect of legume intercropping on sugarcane yield, (ii) assess how agro-environmental and management conditions influence the response of sugarcane yield to inter-cropping, and (iii) assess the influence of legumes in interaction with weeds on sugarcane yield. We combined data from a systematic literature review and experimental data from a network of experiments conducted on the tropical island of La Re ' union. 315 observations (one-year x site x intercropping treatment) were analyzed with mixed effects models to assess the effect of legume intercropping on sugarcane yield and factors influencing the response of sugarcane yield. Intercropping with legumes resulted in a 3.34 % lower sugarcane yield on average compared to the monoculture treatment, but with high variation from -65 to + 47 %. Our study highlighted how the competition of legumes on sugarcane yield is reduced by higher annual temperatures and soil organic carbon. Late sowing and early destruction date of the legume mitigated the negative effect of legumes on sug-arcane yield. Our study also showed that the negative impact of legumes on sugarcane yield increased over years of intercropping. Further studies are needed to better synchronize legume sowing and destruction dates while reducing trade-offs between expected services (N enrichment and weed control) and disservices (yield loss, costs, and labor time) in sugarcane agrosystems according to the climate and soil context.

Automated summary

Through a meta-analysis of multiple studies, it was found that intercropping with legumes led to a decrease in sugarcane yield, with a high degree of variation. The study also revealed that higher annual temperatures and soil organic carbon reduced the competition of legumes on sugarcane yield, and late sowing and early destruction of legumes mitigated their negative impact. Furthermore, it was observed that the negative effect of legumes on sugarcane yield increased over years of intercropping. Further research is needed to better synchronize legume sowing and destruction dates in sugarcane agrosystems according to the climate and soil context, while balancing expected services and disservices.