Interspecific trade-offs between intercrops promote soil resilience, agricultural productivity, and crop protection: a meta-synthesis

Intercropping (IC) increases crop productivity by improving soil ecosystem functions and agroecosystem resilience to climatic vulnerabilities, thereby contributing to sustainable agriculture. However, quantitative metrics for assessing IC's role in promoting soil ecosystem functions and agroecosystem stability are not yet widely adopted due to perceived challenges. To address this, we conducted a systematic assessment of 21 meta-analyses to evaluate the overall effects of IC on crop productivity, soil nutrients, microbial abundance, greenhouse gas emissions, and crop protection measures. Our results have shown that IC significantly improved land use efficiency and yield production compared to monocropping. However, IC did not have a positive impact on soil nutrients except for SOC compared to monocropping. Notably, fungal and bacterial abundance were significantly increased under IC, suggesting a belowground microbial facilitation process. Moreover, our results indicate that pest and disease incidence were reduced under IC compared to monocropping. Specifically, legume-based IC greatly decreased disease incidence and increased predator abundance. These results highlight the significant potential of IC to enhance soil ecosystem functions and sustainability, particularly regarding crop yield, microbial abundance, and the biological control of pests and disease incidence. However, the limited effects of IC on soil nutrients (nitrogen and phosphorus) and N₂O mitigation highlight the need for further investigations under different soil types and climatic conditions.