Soil Sommelier: Dolomitic Limestone

In the Marche region of Jesi, where the Verdicchio dei Castelli di Jesi DOC is demarcated, the soil has undergone studies to see why its wines taste so different from the Verdicchio di Matelica DOC—a region only a few miles away. These DOCs use the same grapes to produce their DOC wines, and while the climate varies slightly thanks to the coastal breezes in Jesi, there is no huge fluctuation in temperature or altitude. 

What does differ is the soil. In the Verdicchio di Matelica DOC, calcareous clay dominates the vineyards, and it’s this that many oenologists believe gives Matelica wines their sharpness—a characteristic that often means they are better after being laid down for a year or two.

In contrast, Jesi wines are rounded and smooth, and ready for drinking within just a few months. As well as the dry maritime climate, what makes these wines so special is the dolomite within the soil, known in geological terms as Dolomitic Limestone. This special compound limestone contains high amounts of calcium and magnesium, and is often used as a supplement by gardeners to reduce soil acidity and add beneficial nutrients for crops such as tomatoes.

“While the DOCs of Jesi and Matelica are in close proximity, they have certain distinct soil characteristics that strongly impact potential soil-grapevine interactions,” states terroir and soil scientist and viticulturist Megan Barlow, in her thesis Soil-grapevine Interactions: Insight from Verdicchio in the Marche Wine Region, Italy.

“Overall,” she concludes, “I speculate that this difference in grapevine stem amino acid synthesis is attributed to soil mineralogy, specifically dolomite in Jesi soils.”

A big conclusion considering most scientists are unwilling to claim that minerality even exists within wine. In the Verdicchio regions, at least, it seems tasting—and rigorous testing—is believing.