Groundcover management effects on soil properties and vine performance in English vineyards

Viticulture in England has expanded rapidly over the last two decades, driven by climate change and the adoption of commercially viable grape varieties suited to sparkling wine production.

This study examined, over two years, the establishment and performance of cover crops and under-vine weed management strategies in two commercial vineyards and one experimental vineyard in the South East of England, representing contrasting soil types. A range of cover crops were established between March  2022 and October 2024, including phacelia, common vetch, faba bean, a perennial mix of berseem, crimson and white clovers with creeping red fescue, and an annual mix of rye and common vetch. In parallel, under-vine weed management practices were evaluated, including herbicide application, mechanical control, and strimming.

Soil assessments included nutrient content, microbial biomass, soil organic matter, bulk density, hydraulic conductivity, soil moisture, soil respiration, and soil microbial community composition (16S rRNA and ITS sequencing). Vine performance was evaluated through measurements of leaf nutrient content, chlorophyll index, canopy area index, grape yield, and juice quality.

Soil organic matter did not differ between cover crop treatments and the control (grass cover). Microbial biomass increased under faba bean at the clayey site in 2023; however, no significant differences among treatments or sites were observed in 2024. As expected, available nitrogen levels were consistently higher in the faba bean treatment across all three sites in both years, although these differences were only statistically significant in 2023.

Regarding soil physical properties, bulk density tended to be higher under faba bean compared with the control, whereas no significant differences were observed in hydraulic conductivity. Soil moisture content was generally lower in the cover crop treatments than in the grass-covered control.

In 2023, grapes from vines adjacent to faba bean cover crops at the clayey site showed significantly higher yeast-assimilable nitrogen (YAN), malic acid, and ammonium-N compared with the grass control. However, these differences were not observed in the following season.

Weeding management influenced soil physical properties and vine performance, with higher soil bulk density and greater vine vigour under herbicide control.

Overall, groundcover management has the potential to influence soil health and vine responses, but the effects observed in this study were not conclusive over the short term. Soil type, seasonal conditions, and the longevity of both treatments and vines are likely key factors regulating the impacts of groundcover management in vineyards.