Cover crops and conservation tillage can improve under-vine soil microbial communities without compromising yield and quality

Abstract

In the recent decades, vineyards have been managed using herbicides and intensive tillage to eliminate competition of adventitious vegetation for resources. However, these practices can negatively impact soil health. Intensive tillage often leads to the loss in soil structure and organic matter, and can decrease microbial biodiversity in soil vineyards (Abad et al., 2021), while herbicides can contaminate the soils and alter microorganism communities. In this context, the use of under-vine cover crops emerges as an alternative to improve soil characteristics and to increase microbial community diversity (Abad et al., 2023). The aim of this study was to evaluate these alternatives (conservation tillage (CT); Trifolium fragiferum cover crop (CC)) to under-vine herbicide application (HB) on grapevine water status, vegetative growth, yield, berry quality and soil bacterial and fungal communities. The experiment was set-up in a Tempranillo vineyard located in Navarra (Spain) over three consecutive seasons (2023-2025).

The impact of under-vine soil managements was dependent on the growing season. In this regard, grapevine water status measured as stem water potential (ψ_stem) was scarcely affected by treatments except in 2024, when HB showed the highest values of ψ_stem. These differences in water status caused changes in vegetative growth, CT and CC showing decreased values of aggregate shoot sections.  Soil management under the vines did not affect yield during the first two seasons, CT vines showing lower values in 2025. Regarding berry quality parameters, little effect was observed, excepting for TSS and total anthocyanin values measured in 2024, when the values observed in CT and CC tended to decrease.

Microbial communities were affected by treatments according to the amplicon sequencing of the bacterial 16S rRNA gene (V4 region) and the fungal ITS1 region performed in 2024. Data revealed that under-vine management did not affect bacterial richness, while composition shifted slightly, with treatments explaining only a small part of the variation among samples. Regarding fungal communities, CC increased their diversity and had only a weak effect on modifying fungal composition. Additionally, results showed that CT increased mycorrhizal species richness compared to HB presumably by the higher diversity in adventitious species. Similarly, CC tended to increase mycorrhizal diversity – compared to HB– in soils and enhanced the root mycorrhizal colonization rate observed under the microscope. Altogether, our results show that alternatives to under-vine herbicide application, such as conservation tillage and cover crops, can improve biological soil health without substantially compromising grapevine yield and berry quality.

References

Abad, F.J., Marín, D., Imbert, B., Virto, I., Garbisu, C & Santesteban, L.G.  2023. Under-vine cover crops: Impact on physical and biological soil proprieties in an irrigated Mediterranean vineyard. Scientia Horticulturae, 311, 111797. https://doi.org/10.1016/j.scienta.2022.111797

Abad, J., Hermoso de Mendoza, I., Marín, D., Orcaray, L & Santesteban, L.G. 2021. Cover crops in viticulture. A systematic review (1): Implications on soil characteristics and biodiversity in vineyard. OENO One,55(1), 295-312. https://doi.org/10.20870/oeno-one.2021.55.1.3599

Acknowledgements

This work was conducted within the frame of two projects, CUALVID funded by Navarra Government (project PC044-045_CUALVID) and MYKOVINE project funded by the Spanish Ministry of Science, Innovation and Universities (REF PID2023-151788OA-I00). N. Torres is beneficiary of a Ramón y Cajal Grant RYC2021-034586-I funded by MCIN/AEI/ 10.13039/501100011033 and by “European Union NextGenerationEU/PRTR”. Maider Velaz and Mónica Galar-Martínez are beneficiaries of pre-doctoral fellowships from the Universidad Pública de Navarra (UPNA). Special thanks to Nahiara Juanena and Aitziber Larrea from Bodega Otazu for their assistance during measurements and maintenance of the experimental setup.