SOIL-GRAPEVINE INTERACTIONS: INSIGHT FROM VERDICCHIO IN THE MARCHE WINE REGION, ITALY

Verdicchio is a white grape varietal notably grown in the Marche wine region of east-central Italy within two Denominazione Origine Controllata (DOC); Castelli di Jesi and Matelica, located less than 50 km apart. Jesi lies in the Apennine foothills near the coast of the Adriatic Sea and produces a smooth wine with crisp acidity. Conversely, Matelica is located in a synclinal valley of a fold-and-thrust belt and produces stronger wine with penetrating floral aromas and bold acidity. Due to the similar macro-climates between DOCs, we hypothesized that terroir parameters, specifically soil composition and nutrient supply to grapevines, contribute to the distinct flavor profiles. To understand possible soil-grapevine interactions, we conducted soil and plant analyses comparing the regions. Soil samples were analyzed using XRD (mineralogy) and XRF (elemental concentrations), as well as tests to determine pH, organic matter, plant available nutrients, and CEC. Nitrogen isotope data and total phosphorus content were collected on soil and grapevine samples. Soil mineralogy is distinct between the two DOCs - Jesi vineyards contain abundant dolomite, while Matelica vineyards lack dolomite. Jesi showed higher soil Mg than Matelica, likely a result of dolomite distribution and dissolution at field pH. Higher Mg available for plant uptake could increase photosynthesis through chlorophyll synthesis. N and P are also critical macronutrients for plants. In the higher Mg, dolomite rich soils Jesi grapevines had 30% higher P content than in Matelica vines, despite higher plant available P in Matelica soils. However, grapevine N content and N isotope fractionation was not different between DOCs though N isotope turnover was faster in Jesi vines. This research focus on soil-grapevine interactions highlights differences in terroir between DOCs and suggests how soil could play a role in the contrasting wine character of Verdicchio from Jesi and Matelica.