Cover crop mixtures enhance multiple ecosystem functions: A global meta-analysis

Cover crop mixtures have been increasingly adopted across agroecosystems
worldwide thanks to their potential to improve soil health and ecosystem
functioning. However, it is not clear whether and how cover crop
mixtures vs. single cover crops might influence different
ecosystem functions. Here, we selected 1,895 paired data from 61 studies
worldwide to evaluate the role of cover crop mixtures in affecting biomass
production, soil properties, and subsequent main crop yields in comparison
with single cover crops. We also assessed whether the number of plant
species in cover crop mixtures, crop field types, and cover crop
combinations could affect ecosystem functioning. Multi-species mixtures
increased cover crop aboveground biomass by 21.7%, carbon and nutrient
accumulation (C: +27.7%, N: +27.7%, P: +22.8%, K: +24.1%), and subsequent
crop yields by 4.9% compared to single cover crops. These benefits were
most pronounced in paddy fields (e.g., a 35.3% increase in biomass), as
well as in specific species combinations such as milk vetch-rapeseed
(32.8%) and milk vetch-ryegrass (36.0%). Also, multi-species cover crop
mixtures increased subsequent soil moisture content (+1.5%), total soil
nitrogen (+5.8%), soil microbial carbon (+37.8%), soil microbial nitrogen
(+37.6%), Chao1 index of fungi (+12.6%), and decreased soil bulk density
(-7.0%), soil electrical conductivity (-9.5%), and polyphenol oxidase
activity (-7.0%). However, effects on soil pH, organic matter, and most
nutrients were neutral unless specific combinations. Synthesis and
applications. Multi-species cover crop mixtures significantly
enhance agroecosystem productivity and soil health, particularly in paddy
systems and when combining functionally complementary species (e.g.,
legumes with Cruciferae, legumes with Gramineae). Farmers and policymakers
should prioritize tailored mixtures over monocultures to optimize biomass
production, nutrient cycling, and yield resilience. For maximum impact,
mixtures should align with local conditions—such as using milk
vetch-rapeseed or milk vetch-ryegrass in humid regions—to advance
sustainable agriculture and climate adaptation goals globally.