More about our soils

Last month we discussed how our calcium-carbonate rich (CaCO3) soils provide innumerable benefits here at Apu Winery. We would like to explore this subject more, focusing on how the pH and nutrients of our limestone soils affect the acidity (and therefore the general flavor and quality) of our Peruvian high-altitude wine.

Our soils have a pH between 7.8 and 8, which means they are moderately alkaline. Alkaline soils, especially calcareous alkaline soils, tend to produce grapes with higher acidity. As Jon Iverson states in "Home Winemaking Step by Step", most grapes should have a pH between 3.2 and 3.4 (35) when picked. With the assistance of our soils, our grapes easily reach the desired pH before harvest. For example, last October, at peak ripeness, our 2018 Sangiovese grapes measured a pH of 3.32. We can thank the crumbly layers of earth that provide a habitat for our roots and vines for this.

Calcareous soils cause acidity in grapes and wine in a couple of ways. First, calcareous soils don’t retain heat and therefore have lower temperatures than other types of soils. Because of this cooler temperature, the grapes ripen more slowly, allowing them to develop perfect ratios of sugar and acidity. Second, calcareous soils are high in calcium but low in other nutrients such as potassium. It has been shown that the combination of low potassium and high calcium produces grapes and wines with optimum acidity (Tablas).

Calcareous soils not only lack potassium, but also tend to lack nitrogen, phosphorous, zinc and iron (Management). We add these nutrients to our drip irrigation system to ensure the plants get what they need to produce healthy, robust grapes for our high altitude wine.

Sources:

Iverson, Jon. Home Winemaking, Step-by-Step: a Guide to Fermenting Wine Grapes. Stonemark Pub. Co., 2009.

“Management of Calcareous Soils.” Calcareous Soils | FAO SOILS PORTAL | Food and Agriculture Organization of the United Nations, www.fao.org/soils-portal/soil-management/management-of-some-problem-soils/calcareous-soils/en/.

“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.

On Top of the World at Apu Winery

Apu Winery is unique for a multitude of reasons, including its high-altitude, proximity to the jungle, pruning schedule and soils. For our first blog post, we would like to focus on the significance of the elevation of our winery and vineyards, which reach an astounding 3,300 meters (10,826 feet). Curious oenophiles often ask us: how does this altitude affect the viticultural conditions and the flavor of our wine? What are some of the challenges we face when working so high in the Andes? There are many successful high-altitude vineyards across the world, including Colomé Winery in Salta, Argentina (3,108 meters/10,200 feet) and LVMH Winery in China (2,600 meters/8,530 feet), proving that it can be beneficial to grow grapes in the world’s most extraordinary mountain ranges.

First, here at Apu Winery, we benefit from a drastic thermal amplitude. Daytime temperatures can reach 40 °C (104 °F), while nights can cool to 2°C (36 °F). However, due to our proximity to the jungle, it never freezes in the Curahuasi Valley, as it does in areas farther away from the equator. These hot days and cool nights provide acidity and balance, important qualities of a fine wine.

Furthermore, because of our extreme elevation, we are closer to the sun. This proximity to the UV rays makes our grape skins thicker, allowing for more concentrated flavors, aromas, and color in the fruit. Also, polyphenols develop in these dense skins, which makes wine our wine rich in antioxidants.

It is widely known that there is less oxygen at higher altitudes. We believe the lack of oxygen works in our favor during the wine-making process, as it delays fermentation. A slower fermentation allows for increased extraction of flavors, aromas, and colors from the grapes and thus makes a more full-bodied, delicious wine.

Although there are many positive aspects to growing grapes and producing wine in these extreme conditions, there are also challenges at 2,850- 3,300 meters. Our vineyards are located on a mountainside where the slope can exceed more than 40°. This inclination creates logistical complications; no machines can operate here, so we prune, harvest and weed by hand. Moreover, although the lack of oxygen is helpful during the fermentation process, it hinders growth at our elevation. This means plants develop at a slower rate and grapes are smaller than in vineyards at lower altitudes.

We have found numerous benefits to growing grapes and making wine at 2,850-3,300 meters. Our proximity to the sun, oxygen levels, and temperature range are all factors that influence the quality of our wine. Some of them pose challenges, while others are beneficial. In the end, we are extremely pleased with the high-altitude wine we make at Apu. We hope you can try a bottle from our second harvest, to be released in Lima in January of 2019!