The Hole Truth about Terroir?

by Tom Fiorina on May 17, 2013

Terroir, that French concept of a combination of characteristics (soil, climate and human interaction) that express the soul of a place, is often used to define the individuality of a wine. In Burgundy, where monks began studying the soil as early as the 7th century to identify where to plant their vines, the concept of terroir is high art. It’s uniquely Bourguignon to talk about “Climats,” plots of land with precisely defined limits that take into account geography, history, archeology, grape variety, traditions, geology, expertise, landscapes, towns, genealogy, reason, passion, ancestral acts, customs, meteorology, oenology, culture, viticulture, toponymy and biodiversity.

The notion of "climat" in Burgundy is different from that of a meteorologist.

The notion of “climat” in Burgundy is different from that of a meteorologist.

They’re very serious in Burgundy about terroir. If you need proof, just consider that they have over 1,200 Climats across the region, and that all of them have names. Some are for geographical characteristics (Le Montrachet, for example, which means “Bald Mountain”). Others are named for manmade creations (such as Derrière le four, which indicates the presence of ancient coal ovens—four is French for “oven”). One of the best known is La Romanée, named for its proximity to an ancient Roman road.

Les Climats de Bourgogne had even received 50,000 signatures for its UNESCO World Heritage listing application in 2013, before being removed (along with the Caves de Champagne) this spring by the French Ministries for Ecology and Culture. Promoting wine in France always involves an element of suspicion from health authorities, so the government evidently felt safer choosing two alcohol-free contenders, the Grotte Chauvet with its prehistoric cave paintings in the Ardèche region and the volcanoes of Auvergne.

It would surprise many in France to learn that the wine region just behind Burgundy in knowing its soil so well is not Bordeaux. It’s actually probably the Mediterranean island of Corsica. I learned this last fall when I visited the CRVI de Corse (the Centre de Recherche Viticole or, in English, the Vineyard Research Center of Corsica) in the small village of San Giuliano on the island’s east coast.

The six-member CRVI staff supports the island’s wine industry with applied research in vineyard management, winemaking (oenology and microbiology), and native grape varieties and yeast. Agricultural engineer Gilles Salva is responsible for providing the island’s winemakers with vineyard management advice and research on 17 local grapevine varieties being grown at the center.

Natalie Uscidda, a microbiologist who studied at Montpellier’s school of œnology, works on wine fermentation and microbiology. Her research helped to develop the two, principal winemaking yeasts used on the island.

Lionel Le Duc, passionate about stones (and terroir).

Lionel Le Duc–passionate about his terroir.

I also met with Lionel Le Duc, a soil engineer who has been studying Corsican terroir for the past 12 years (he also is responsible for the center’s œnology laboratory), to discuss the findings of his research, presented in July 2012 at the IXème Congrès International Des Terroirs Vitivinicoles.

Le Duc is passionate about geology. In fact his small office is filled with rocks and cloth sacks stuffed with soil marked with names like “Ajaccio” and “Cap Corse,” the areas where he collected the soil. His father-in-law, he says, sculpted architectural elements (grave markers, garden pieces, fountains, benches, etc.) in the largest marble quarry in Corsica. This got him interested in stone (he also sculpts, he says), and provided him access to stone samples from all over the island.

Complementing this artistic bent is his university studies in geology, biology and agriculture. Following a one-year internship at INRA (the Institut National de la Recherche Agronomique— France’s national agricultural institute), he did his one-year mandatory French military service in Toulon, where he was responsible for an analytical laboratory.

He began working at the CRVI in San Giuliano in 1998. Several years later he discovered a gold mine of information that at first glance might not have been evident to the average person. It seems that a geologist working with the BRGM (Bureau de Recherches Géologiques et Minières) in Corsica had spent the better part of his career making holes all around the island. This dedicated digger had made, in fact, over 10,000, 1.2m-square holes throughout the island’s 90,000ha of agricultural land. Using the data from these holes, along with others Le Duc made in selected vineyards using criteria developed by INRA that looks at soil mineral type, the soil density and its depth, the drainage potential, and other criteria (providing, as Le Duc puts it, “A basic unit of terroir”), allowed him to then use an INRA-developed 3D visualization software to create an interactive cartographical map of the soil structure in the island’s AOC wine appellations.

And since 2002, with money from the island’s regional development fund and the French government, he has set up a protocol to use this 3D map to examine the potential of the island’s three indigenous grape varieties—Vermentinu, Nielluciu and Sciaccarellu. This protocol consists of selecting parcels of vines within a vineyard that represent a desired standard (soil type, exposition, grape variety, etc.). Each parcel consists of approximately 100 vines of the same age, plantation density, clone and rootstock. The soil cultivation must be the same, as well as the vine management (pruning, shoot training, canopy management, etc.). To ensure consistency, the parcel is taped off from the other vines and Le Duc (or a CRVI technician) is responsible (other than for disease management, which is left up to the winemaker) for the soil and vine management within the parcel, including harvesting the ripened grapes.

Some of the older wine bottles in the CRVI center, allowing the researchers to judge the aging potential of their micro-vinification studies.

Some of the older wine bottles in the CRVI center, allowing the researchers to judge the aging potential of their micro-vinification studies.

Micro-vinification of the grapes harvested from each parcel produces approximately 30 bottles of wine. This wine is then analyzed in three ways. First, it is evaluated by a trained jury of tasters. A laboratory analysis is then done to determine its physical and chemical components. And, finally, the wine’s aromatic components are analyzed. Bottles in the CRVI cellar date back to the early 1980s, allowing the aging potential of the wine to be evaluated.

Most of the initial studies concentrated on the Balagne region that makes up the AOP Calvi appellation in northwestern Corsica. A total of 22 parcels have been studied over the past decade. But other study-parcels are located, or will be placed, in the island’s other eight appellations.

The real value of such a long-term study, he explains, is helping winemakers to increase the value of their grapes. A winemaker, he says, can then determine the best time to harvest the grapes to create different styles of wine (with more or less fruity flavors, with more or less color, with more or less aging capability, etc.). Such long-term studies can also show how different soil and vine cultivation techniques, different rootstock and clones, and different soil types affect wine quality.

As an example of the precision that is possible with such methodology, he cites the example of the Clos Culombu vineyard in the Calvi appellation. Winemaker Etienne Suzzoni has divided an already existing six-ha parcel into seven different micro-parcels with three different Vermentinu clones. Through micro-vinification of these smaller parcels he’s developed different Vermentinu cuvées that offer consumers different white-wine styles. Data from the parcels are also helping to produce Sciaccarellu grapes with increased color density, something that this variety often lacks in finished wines.

Digging a bunch of holes may never replace a millennium of observations by monks, but it is helping Corsica to understand its terroir better and to make better wine.

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Alain Harvey May 18, 2013 at 16:19

Really a fascinating topic! Terroir is a fuzzy French word that, despite its lack of a clear definition, finds itself at the center of any effort to define wine quality. Finding the right balance of each important terroir component is the ultimate achievement in wine growing. When done well, an ethereal balance of nature and man result in sublime wines
that capture the imaginations of wine lovers everywhere and set standards that all wine growers seek to achieve.

Outside of France, and particularly in the New World, the contribution of soil to wine character has been largely ignored prior to the 1990s. Climate was thought to be of overriding importance in determining wine quality. Even the French, with their illustrious viniculture history, have had to reevaluate the importance of its soils to the uniqueness of her wines, having stripped away much of its character through the overuse of chemical fertilizers and pesticides after WWII.

Now, soil quality is consider paramount in the production of fine wines. When we think of ideal vineyard soils, we must analyze them in their full context – physical,
chemical and biological properties. Again, the correct balance of these constituent parts is
sought to best accommodate the plant and climate as well as the applied viticulture. Other
considerations, such as slope, aspect, and elevation have indirect effects on soil relative to its impact on vine physiology. What is underfoot is an incredibly complex system that we sense is critical to wine quality, yet we don’t fully understand how or why. However, thanks to oenologists such as yourself and scientists such as Leonel Le Duc this situation is rapidly changing.

Site selection is the single most crucial decision to you will make as a wine grower – odd,
perhaps, since you have not yet planted a vine or squished a single berry. Once this decision is made, terroir realities can be determined through years, if not decades, of winemaking, and only then can excellent terroir be proclaimed. The best vineyard site is not necessarily the place with the best view, or the most expensive land, or the one closest to the local tavern. It’s the one that has the best combination of an infinite set of variables that intertwine to produce a great bottle of wine. Site selection is a process, not a “this is the place” moment. It involves careful study of records, discussion with neighbors, digging holes, soil tests, conversations with consultants and a lot of walking around and scratching your head. The final act of committing to a site is an act of faith.

The soil food web is relatively new to the viticulture lexicon. The myriad of organisms are often present in astonishing numbers, Each of these organisms has its own important function in the web and all are food for each other. Actinomycetes help to decompose organic matter. Fungi and bacteria create compounds that help to bind soil particles. Nematodes are involved in nutrient cycling. Soil arthropods help to shred dead plant materials, greatly enhancing decomposition. Earthworms mix and aggregate soil particles and stimulate microbial activity. We are only now beginning to understand how this complex world impacts plant life and how it might influence
wine quality. Most of the evidence for any benefit from applying food web products is anecdotal. Grape growers should be attentive to this underground
world and employ practices that enhance and preserve the food web. Reducing chemical inputs, aerating soils, reducing soil compaction, improving soil drainage, adding compost when needed are all practices that can contribute to the sustainability of the subterranean life.

As you point out, soil physical properties are important to wine quality. However, as with chemistry and the food web, these attributes can vary dramatically, yet still contribute to fine wine production. Consider the wines in Napa Valley, where great Cabernet Sauvignon is grown both on the deep bale loams of the valley floor and the shallow, rocky soils on the hills above the valley. Even soils as varied as these have common features that make them suitable for making great wine. The common denominator among all great vineyard sites is that they are well drained. They strike a balance between adequate depth, good drainage and water holding capacity so the vine will not suffer too much in summer, yet the soils will drain amply if late season rains afflict the ripening period.

Soil types that provide these features are all over the map – literally and figuratively – from the clays of Pomerol to the calcareous soils of Burgundy and schists of the Mosel.

Vintners worldwide as reflected by the ongoing research in Corsica, are increasingly using every tool at their disposal to predict the performance of their soil.

You have one shot at the right soil. If you are in Napa or Bordeaux, you can look over the fence or across the road and see what your neighbor’s vines are doing. If you are in New England, you have to use a crystal ball and any information you can develop on your own to make the best educated decision possible to validate a site for wine grapes.

Thank you once more for a fascinating article!

Tom Fiorina May 19, 2013 at 11:54

Your comment expands on my article in many ways, Alain, particularly in illustrating that the meaning of this fascinating and illusive subject of terroir cannot possibly be found in a hole. Your saying that it is probably one of the most defining criteria for making great wine is on target, and proves to me again that wine buyers or writers who really care about defining outstanding wines need to look closely at the vineyard that produces the grapes. I’ve also been spurred, upon further reflection, to add a question mark to my original title, as I cannot begin to suggest that I have discovered the definitive definition for terroir. Thanks for reading and commenting about my Vine Route articles. Please let me know if you’d ever want to contribute a guest article about terroir or some other wine-related topic. Maybe something about how the definition of terroir in the U.S. differs from the metaphysical approach that exists in France.

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