Boosting Grassland Performance through Plant Diversity and Soil Carbon Processes

Agricultural systems face a dual and often conflicting challenge: sustaining food production while restoring soil functions under climate and land degradation pressures. Soils are increasingly recognized not only as the foundation of crop productivity but also as a major lever for climate mitigation through carbon storage. However, the relationship between agricultural production and soil carbon accumulation is neither linear nor universally synergistic. Evidence across pedoclimatic gradients suggests that gains in soil organic carbon (SOC) may reach functional plateaus, or even trade-offs, once SOC levels exceed thresholds around 1.5–2%, where additional carbon does not proportionally translate into yield or multifunctionality benefits. This indicates that the key question is no longer how much carbon soils can store, but how carbon is functionally integrated within agroecosystems.

Plant diversity represents one of the most powerful yet underutilized tools to modulate these soil functions. While strong links between biodiversity and ecosystem multifunctionality are well established in natural and semi-natural ecosystems, agricultural systems offer a unique and largely unexplored advantage: plant diversity is deliberately manageable. Through intercropping, diverse grassland mixtures, living mulches, rotations, and cultivar selection, both taxonomic and functional diversity can be actively designed. Unlike natural systems, where diversity patterns are emergent, agroecosystems allow diversity to be treated as an experimental and management variable with direct implications for belowground processes.

Despite increasing interest in crop diversification, most research still focuses on aboveground productivity or single ecosystem functions, while mechanistic links between plant diversity, root dynamics, microbial regulation, and SOC stabilization remain poorly resolved. In particular, the role of root traits, root turnover (“life and afterlife” effects), and plant–microbe interactions as mediators of diversity effects on both yield and carbon persistence is still underrepresented. As a result, current knowledge largely relies on correlative patterns rather than process-based understanding, limiting our ability to predict when plant diversification enhances synergies or triggers trade-offs between production and soil carbon storage.

This Research Topic seeks to move beyond descriptive relationships by addressing how plant diversity reshapes soil carbon dynamics and productivity simultaneously, and under which conditions these processes reinforce or constrain one another. We aim to identify management strategies that optimize the functional quality of soil carbon, enhance soil structure and water regulation, and improve system resilience, rather than focusing solely on carbon quantity.

Themes of interest include (but are not limited to):
· Mechanisms underlying synergies and trade-offs between yield and SOC
· Root traits, root turnover, and “afterlife” effects on soil processes
· Microbial mediation of carbon stabilization and decomposition
· Plant–soil feedbacks in diversified agroecosystems
· Functional vs. taxonomic diversity effects
· Soil organic matter formation pathways
· Structural and biophysical controls of carbon persistence
· Nature-based solutions for multifunctional soil management
· Physiological and biochemical plant responses to diversity
· Climate adaptation through diversified cropping systems

Studies from any agroecosystem where plant diversity is actively managed are welcome. We encourage submissions that combine process-level insight, multifunctional perspectives, and management relevance, including original research, syntheses, and perspectives.