Serious wine drinkers may pledge allegiance to certain soil types, crediting one or another with a certain flavor or sensation they detect in their glass. Limestone soils, which underpin some of the world’s most coveted vineyards in Burgundy, Chablis, and Champagne, are often linked to a particular wine’s precision, brightness, or linearity. The word “minerality” is frequently associated with wines made from grapes grown in limestone soils.
The connection between soil and flavor is, however, muddled at best for casual consumers. And even for people who make a living growing, producing, tasting, or selling wine, trying to connect the dots between the properties of the soil and the properties of a finished wine can feel akin to cracking the Voynich code.
What do we mean when we say limestone soils, exactly? And how do those soils affect the flavor in the glass? We reached out to scientists, terroir specialists, and producers to find out more.
What, exactly, is limestone?
Limestone is a sedimentary rock containing calcite, a calcium carbonate mineral. Limestone soils are derived from parent material, either calcareous or dolomitic. (The difference is subtle: dolomite is essentially limestone, but some of the calcium content has been replaced with magnesium. Limestone is made up of calcite, or calcium carbonate. Essentially, dolomite is calcareous, but a lighter or less pure version.) They contain at least five percent and up to 50 percent calcium carbonate or calcium magnesium carbonite. These details are easy to overlook, but essential to understanding limestone’s essence and its effect, argues terroir and geology expert Brenna Quigley.
“When we talk about limestone soils, we’re talking about soils derived from limestone bedrock,” Quigley says. “The bedrock is a solid, immovable piece of the Earth’s crust. It’s an intact piece of the continent.”
The soil, on the other hand, consists of organic matter that has broken down over time, including portions of calcium carbonate in that limestone bedrock which has weathered over time as the Earth’s surface is exposed to water and air. Add water, air, and time, and you have limestone soil.
“Ultimately, when we’re talking about limestone soils, we’re talking about residual soils where mineral material is derived from the limestone bedrock,” Quigley says. “These soils are all going to be alkaline and have a basic PH of around eight. There will be active lime present, which is essentially calcium carbonate in the soil itself, which makes it available to the plant.”
Limestone soils can be found across about half of France, one-third of Italy and Spain, and parts of the Eastern Mediterranean and Caspian Sea region...
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