Interrow cover crops in a semi-arid vineyard increase plant beneficial functional potential of the soil microbiome, both in vine rows and interrows, a benefit that increases with cover crop duration

Summary

This three-year field study in California vineyards examined how interrow cover crops—specifically phacelia (native) and rye (introduced)—influence soil microbiome structure and function in both interrow and adjacent vine row soils. By year three, phacelia generated the highest microbial biomass and network complexity, with cover crops reducing predicted fungal pathogen prevalence and supporting nutrient cycling functions. The findings suggest that long-term interrow cover cropping builds resilient soil microbiomes in water-limited environments, with benefits extending beyond the sown area to vine rows even after cover crop termination.

Regional applicability

Whilst this study was conducted in California's semi-arid conditions, the mechanistic findings on cover crop-driven microbiome shifts are potentially transferable to analogous UK Mediterranean-style viticulture regions (e.g. southern England) and water-stressed horticultural systems. However, UK vineyards experience cooler temperatures and higher rainfall, which may alter the recruitment and persistence of the communities observed; direct validation in UK vineyard conditions would be prudent before widespread adoption recommendations.

Key measures

Microbial biomass, fungal-to-bacterial ratios, microbial network complexity, microbial community composition (likely 16S rRNA and ITS sequencing), functional predictions of microbial processes, nitrate concentration, labile organic inputs

Outcomes reported

The study assessed temporal and spatial changes in soil microbiome composition, microbial biomass, fungal-to-bacterial ratios, and functional potential across three years of interrow cover crop management in vineyard soils. Functional predictions indicated changes in pathogen prevalence and nutrient cycling capacity, with nitrate identified as a key driver of microbial differentiation.

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