Andean Limestone Soils
Updated: May 22
In this blog post, we would like to discuss our limestone soils and how they affect the wine we produce at Apu Winery. Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) that forms from the accumulation of shell, coral, algal and fecal debris in shallow marine waters. Over millions of years, the oceanic crust (Nazca Plate) has been subducting under the continental crust (South American plate), forming the Andes and lifting this rich material up into higher altitudes.
Terroir is a term used to describe a combination of several factors that create a winemaking environment. All of these factors influence the quality of grapes and wine. We have mentioned unique aspects of our land in previous blog posts, including our high altitude, microclimate, thermal amplitude and the slope of our hillsides, all of which form the terroir at Apu Winery.
However, we believe one of the most impressive characteristics of our vineyard is our white, chalky calcareous soil. As Alice Feiring says in her book Dirty Guide to Wine: “Terroir is a lot of things other than soil. But it is the soil that gives the vine a fighting chance” (32). It is extremely difficult to make a good wine from vines raised in soils that aren’t conducive to grape-growing. The soil in our high-altitude vineyards is argilo-calcaire (a mix of limestone and clay) with a 20-30 centimeter loam top layer. Beneath this loam is a material rich in calcium carbonate, the principal chemical component of limestone. With this structure, our plants can easily penetrate the crumbled rocks and sand, allowing them to form deep roots for easier nutrient uptake.
Besides the increased nutrient uptake due to deep roots, there are many other advantages to growing vines in limestone soils. In “Why Limestone Matters for Wine Grape Growing” on the Tablas Creek Winery Blog, Dr. Rice describes other important benefits, including: water retention, good drainage and high resistance to diseases. The ability to retain water is extremely important to us during dry season in Andes, while drainage and resistance to diseases are equally crucial during rainy season.
Even more remarkable to us, our soils are similar to those found in the Côte d’Or region of Burgundy, France. As Feiring states “Not all of Burgundy is that perfect mix of limestone and clay (argilo-calcaire). In fact, it is only in the Côte d’Or where that sublime, elastic kind of combination exists” (115). She also notes that of only 570 Premiers Crus wines (the second-highest classification level in Burgundy), more than 460 are produced in the Côte d’Or, where these limestone soils are found in vineyards (116).
After years of searching for the perfect terroir among the snow-capped peaks of the Peruvian Andes, we found this slope with white, chalky limestone in the Curahuasi Valley. Although many factors create the wine making environment here at our high-altitude vineyards, we are certain that our argilo-calcaire soils provide the ideal conditions for grape-growing and wine-making.
Feiring, Alice, and Pascaline Lepeltier. The Dirty Guide to Wine: Following Flavors from Ground to Glass. The Countryman Press, a Division of W.W. Norton & Company., 2017.
“Why Limestone Matters for Wine Grape Growing.” Tablas Creek Vineyard Blog, 26 May 2010, tablascreek.typepad.com/tablas/2010/05/why-limestone-matters-for-viticulture.html.