Multi-species grass mixtures enhance soil functioning in managed grassland mesocosms

Multi-species grassland mixtures are gaining popularity in managed grasslands, particularly as a strategy to improve soil functioning and subsequently soil health and climate regulation. However, mechanistic data on the relation between plant diversity and the greenhouse gas (GHG) balance of the soil are still sparse. We conducted a full-factorial mesocosm experiment to determine whether multi-species grassland mixtures can enhance the delivery of ecosystem services compared to traditional perennial ryegrass monocultures. Treatments included two plant communities, two soil types and three cutting frequencies - representing land use intensities under controlled conditions. We measured effects on greenhouse gas (GHG) effluxes (CO2, CH4 and N2O), above- and belowground productivity as well as functional catabolic diversity of soil microbes Linear Mixed Models (LMMs) revealed that plant community and soil type impacted all greenhouse gas effluxes, while cutting frequency only impacted CO2 efflux significantly. Multi-species grass mixtures significantly elevated primary productivity compared to perennial ryegrass monocultures, and influenced functional microbial diversity, even overriding soil type (and therefore legacy) effects on functional microbial diversity over a short timeframe. These improvements in soil functioning can improve the delivery of crucial ecosystem services such as climate regulation, food and feed production and soil habitat and nutrient cycling, which underlines the potential of species-rich grassland mixtures in multifunctional grassland farming systems. Future research should explore long-term field dynamics and validate these findings by making carbon budgets to support climate-smart management strategies.