Organic mulches in grapevine shape bacterial communities in specific vintage and location.

The interest in sustainable and ecologic agricultural practices in grapevine has grown significantly in recent years in the context of ecological transition. Organic mulches are alternative practices influencing soil moisture, erosion, structure and weed control. However, their effects on the soil and must microbiota remain unknown. Understanding the relationship between vineyard management and microbiota may help to choose the optimal practices, reducing environmental impact and improving wine quality. We aimed to evaluate the effects of five soil management practices on soil and must bacterial communities along three consecutive years in two vineyards of La Rioja, Spain using a metataxonomic approach. Two conventional practices (Herbicide use and Under-row Tillage) were compared with three organic mulches applied on the vine row (Grapevine Pruning Debris, Spent Mushrooms Compost and Straw). The main factors shaping the soil bacterial community were year followed by location. The treatment effect on soil microbiota was weak and could only be found when analyzing each year and location individually. In particular, the bacterial communities of the conventional practices clustered in all years and locations. However, organic mulches were only grouped in the third year of study at both locations. Besides, the practices did not affect the must bacterial communities and were driven by year and location. These results show that the practices have a weak effect compared to year or location and that their impact is detected in the soil but not in the must. Therefore, organic mulches could be a sustainable viticulture alternative and should use it in the long term. • The organic mulches affect soil bacterial communities in the vineyard. • Year and location are the main factors shaping soil and must bacterial communities. • Soil bacteria microbiota does not influence the winemaking process. [ABSTRACT FROM AUTHOR]