Soil health in the vineyards of North-Western Italy

Introduction Soil health is the ability of soil to provide ecosystem services to the best of its potential, and soil health indexes (SHI) have been developed to capture the physical, chemical and biological aspects of soil health. However, in viticulture, high-quality wines are typically achieved when grapevines experience moderate stress, which promotes the biosynthesis of secondary metabolites. The assessment of soil health is often aimed at maximizing crop yield, and SHI may therefore provide unsuitable results in viticulture.Methods In this study, we analyzed the characteristics of more than 2,800 vineyard soils from a soil database in North-Western Italy, a region renowned for high-quality wines. We calculated the SHI using the Comprehensive Assessment of Soil Health (CASH), and evaluated whether appellation areas differ from the broader background of vineyard soil properties.Results The most common red-berry varieties grow on significantly different soils from the other grapevines, richer in clay and carbonates, with low contents of extractable microelements and phosphorus. Areas designated as Denominazione di Origine Controllata e Garantita (DOCG), representing the highest quality classification of Italian wines, differ from Denominazione di Origine Controllata (DOC) areas. Although DOCG vineyards generally exhibit lower chemical fertility, they show more favorable physical soil health indicators.Discussion This suggests that the terroir of the DOCG wines results from a combination of inherent site characteristics, contrasting chemical and physical soil properties, and human management practices, aimed at reducing grapevine vigor in conditions where water availability is relatively high.