Definition: terroir revealed (the)

Interview with Claude Bourguignon by Jacques Perrin, member of the European Grand Jury, Editor-in-Chief of VINIFERA, CAVE SA. Claude Bourguignon is a Doctor of Science, Director of the Laboratory for Microbiological Analysis of Soils (LAMS - field and laboratory analysis of the chemical and biological properties of agricultural soils, in order to assist farmers with soil management in France, Europe, America and Africa), agricultural engineer (INA PG), member of the Ecology Society, member of the American Society for Microbiology, lecturer at the first French Chair of Pedology and Soil Microbiology (Beaujeu), author of the book: "Le sol, la terre et les champs" (Ed. La Manufacture/Sang de la Terre. 1989), soil expert for the EEC. His constant movement between the field and the laboratory, between policy and fundamentals, gives him a comprehensive approach to soil.

• Can you describe your career path?

My wife and I were at INRA and during our research we developed a method for measuring soil activity, i.e. determining whether the soil is alive or not. It is a comprehensive method of analysis, covering physical, chemical and biological aspects, whereas for 50 years everything was based solely on physical analysis, granulometry, as if the soil were not a living element. So we decided to leave the Institute and in 1989 we founded an independent laboratory, a laboratory for microbiological analysis of soils, which was a bit crazy at the time... In fact, we had no idea whether the agricultural world would respond to this need to define a biological dimension of soils, because we were still in the midst of the chemical era: soil is a medium, I put fertiliser on it and then it's up to industry to transform the product and do what it has to do. What we were trying to explain to the people at INRA at the time was that if you want quantity, you adapt the soil to the plant, but if you want quality, the plant has to adapt to the soil. Thus, for centuries, winegrowers have adapted Vitis vinifera to the concept of terroir. In Burgundy, they created Pinot Noir and Chardonnay. Pinot Noir is the result of a thousand years of adaptation of Vitis vinifera to the terroir of Burgundy. We tried to get this across. It wasn't easy and we struggled at first...

• What are the keys to understanding terroir?

First of all, it should be noted that the concept of terroir only exists in French. It is a word that cannot be translated into other languages. Terroir is defined by four parameters. First of all, climate – Europe is fortunate to have a temperate climate. The advantage of such a climate is that it allows for a subtle balance between acidity, alcohol and phenolic ripeness. Terroir is also defined by topography – to make a great wine, you need sloping ground because, on the one hand, it will get more sunlight and, on the other hand, the topography will allow excess water to drain away. If you leave a vine in water, it will start to grow enormously. Let's not forget that the vine is a plant from the swampy forests of the Caucasus and can grow up to 40 metres high. In order to produce great wines, man tortures it. He prunes it and keeps it close to the ground where it can benefit from the heat of the stone and ripen its grapes. Water must not be allowed to stagnate. This explains the major interventions carried out in the Bordeaux region in^{the 17th} century to drain the Médoc, which was a marshy area. The gravel lies on clay. Once man had installed drains to dry out the clay, the gravel was able to play its filtering and drying role. In a way, it created a dry climate within a humid climate.In the Médoc, the topography was even deepened, with gravel brought in from the Gironde to create steeper slopes. Thirdly, terroir is about geology: there are three types of rock on the planet. Ninety per cent of the rock is acidic, consisting of schist (75%) and granite (15%). Finally, there are limestone rocks (7%) and volcanic rocks (3%). It so happens that Vitis vinifera is a calcicolous plant, meaning it thrives in limestone. Fortunately, France, Italy and Spain are limestone soils. In particular, 55% of France's soil is calcareous. Furthermore, we often find that great white wines are produced from schist, granite and gneiss. In the United States, for example, only 3% of the soil is calcareous, so they compete with us more on white wines than on red wines. Europe must understand that it is exceptionally fortunate to have so much limestone and different types of limestone (Cretaceous, Jurassic, etc.). Volcanic rocks are even rarer, and we know that they can be used to produce very fine wines, such as Tokaji (Tokay).

And finally, there is the soil: Vitis vinifera attacks the different rocks on which it grows and thus produces clay. Each rock releases the elements it contains under the attack of the plant. For example, in Morgon, these are manganese granites, which are found in the wine. Hence the expression, "morgonne" wine. Obviously, if fertilisers are used, the effects of the terroir will be erased. The vine needs to sink its roots deep into the soil. A great terroir must cause growth to stop. At a certain point, the vine must stop growing and focus on its grapes and carry out its translocation. To do this, they need deep roots. They continue to ripen their grapes while stopping growing. This is what makes a great terroir, one that forces the vines to reach deep down. For there to be a great terroir, the roots must be able to go down, to descend. There are two solutions: the Burgundy and Alsace or Côtes du Rhône system, where the rock has been cracked by tectonic movements. If the rock is cracked, the roots can slip in and go very deep.

Conversely, there are what we might call man-made terroirs, as is the case in Bordeaux, as we saw above. There is an extraordinarily filtering top layer that allows the vines to take root, with clay at the bottom. So it's not just any terroir that can produce great wines.

• How did the various parameters that enable us to understand the concept of terroir come about?

This complexity of geography/climate/topography/soil has been highlighted by man throughout history. In other words, man has selected Vitis vinifera in specific terroir conditions. They have therefore created grape varieties such as Pinot Noir in Burgundy, Cabernet in Bordeaux, Syrah in the Côtes du Rhône, etc. By continuing to cultivate Vitis vinifera in the same place for a thousand years, you end up creating mutations that adapt to these climatic conditions and are perfectly suited to expressing the terroir. Vitis vinifera that failed to ripen in Burgundy was not harvested; the bunches were left on the vine and removed, and only those that were ripe were harvested. You do this for a thousand years and in the end all your Pinots ripen in the Burgundy climate, even though it is not originally a climate for Vitis vinifera, which is a Mediterranean plant. In each region, thanks to mass selection, man will preserve the vines that are best suited to the terroir.

Pruning is also important in this process, as it seeks to optimise grape ripening based on climatic data. Since phylloxera, we have had to pay attention to rootstocks, selecting those that are suited to the terroir (early ripening, proportion of active limestone, etc.). I also think that there is a lot of work to be done in Europe to restore our vines to their original state.

Another factor that varies depending on the terroir is planting density. In the past, the further north you went, the higher the planting density. In Champagne, for example, there were 60,000 vines per hectare with one bunch of grapes per vine, which was the only way to ripen the grapes. In Burgundy, there were 1,000 vines per labour unit, or 24,000 vines per hectare. This density took a big hit during the Revolution when it became necessary to start paying labourers. Horses were introduced, and it became necessary to plant in rows and reduce densities. Everyone reduced their densities in an attempt to lower production costs. Today, on the contrary, we should be asking ourselves which of the great terroirs can afford to be planted at 30,000 vines per hectare and move in that direction. There are undoubtedly a few very prestigious grands crus that could afford this luxury!

This complexity of terroir, grape variety, pruning height and density will give us grapes that we will vinify in the cellar. However, what is also interesting is that the final stage of typicity is the stone used for the cellar, meaning that if you don't use local stone, you won't be able to make local wine. I have an interesting anecdote about this: there is an example of an estate in the Arbois appellation that wanted to expand its cellar, not with Arbois stone, but with stone from Burgundy, from Comblanchien. It was impossible to make Vin Jaune in this part of the cellar! The yeast that makes Vin Jaune lies in the marly limestone of the Arbois region! Here too, the atmosphere of the cellar is a fundamental factor in making wine.

Another fundamental element in understanding terroir: you only have a terroir product if it is fermented. You cannot express the taste of a terroir if the product does not undergo fermentation. What are the fermented products, the great products that can express the concept of terroir? There is wine, cheese, fermented charcuterie, chocolate, tea, coffee, tobacco and perfumes. What is remarkable is that in all these noble products, fermentation transforms them and enhances their flavour.

• Let's go back to the beginning, to the soil and subsoil: what does the biological activity of soils consist of?

The soil is an environment that is home to 80% of the planet's life. Most of the living biomass is in the soil, not above it. Take earthworms, for example: they are as heavy as all other living animals combined. Soil is actually a "fermenter". In living soil, there are about 3 tonnes of microorganisms per hectare that have 350 times more biochemical activity than we do. This means that 3 tonnes of microorganisms per hectare is the equivalent of 1,000 tonnes of human beings per hectare in terms of living energy. The role of these organisms in the soil is to make everything in the soil assimilable by plants. How does this work? There are two levels. First, there is the fauna, the macro-organisms whose role is to eat all the plant waste, digesting everything that plants leave either on the soil or in the soil in the form of roots. The fauna is divided into three groups. One group is called "epigeal", which lives above ground and eats everything that is above ground, everything that comes from the vine above. Then there is the endogeal fauna, which eats all the dead roots. Finally, there is the anecic fauna, large earthworms that come out every night and create vertical tunnels. They come out to eat. They bring surface waste down into the depths, digest it, empty their intestines and, by moving back and forth, mix the organic matter and aerate the soil. The large vertical tunnels they create allow oxygen to descend. Their fundamental role is to break down the material so that microbes can attack it and aerate it. Thanks to them, microbes are able to produce humus. There are three types of microbes: those that produce humus, a process called humification, which is dominated by fungi; these are the only microorganisms capable of attacking lignin. A vine produces a lot of lignin in its prunings. Then there are bacteria and actinomycetes, which are mineralising microbes that transform organic matter back into nitrates, sulphates and phosphates, so that it can re-enter the life cycle. Finally, there is a third type of flora called rhizosphere microflora, which lives in symbiosis with the vine. For example, the vine is mycorrhized with fungi, which live inside the vine's roots, which send them sugar, and the fungi send them nutrients, seeking out phosphorus and many other nutrients in the soil. It's an exchange. It's a very complex world in terms of how it works, and the slightest imbalance can put it at risk. For example, if you burn the prunings, you are on a slope, so the leaves are washed away by the rain, you weed chemically, you prevent plants from growing, there is no more organic matter, so no more epigeic fauna, no more tunnels, the soil compacts, there is no more oxygen, the roots are forced to grow upwards and so there is no more terroir. And then, when I no longer have any nitrates or phosphates in their natural state, what do I do? I buy nitrates, I buy sulphates, I buy phosphates, but they don't come from the terroir. The ancients knew how to keep a vine alive for 100 years, whereas for us, a 20-year-old vine is practically dead. It dies just as it starts to produce great wines, because it is so drained, because we push it so hard. So we need to completely rethink our approach to viticulture. We've made huge progress in oenology, but now we need to do the same in viticulture. I believe that if we can combine good soil management, good vineyard management and oenology, we will produce the greatest wines on the planet in Burgundy, not because I am chauvinistic and my name is Bourguignon, but because it is Burgundy that has taken the concept of terroir to its logical conclusion.

I remember that about ten years ago, when we asked certain estates to stop weeding their soils, the owners said to us: "You don't really think we're going to start working the soil again, do you?" And yet, the concept of terroir also involves this...

In fact, when you taste a wine, you realise that at first it expresses the fruit, the sun, the vineyard above, and as it ages, it expresses flavours of truffle, undergrowth, earth and minerals. As it ages, the wine will increasingly develop earthy flavours...

• Could we say that, like the vine which, as it ages, extends its root system, the wine descends into itself, deepening, restoring the complex, unique flavours of its original terroir, whose singular substance it has captured?

Yes, and what is interesting is that when you look at very old writings, Antoine Béchamp, who was the first to discover microbes, had a remarkable idea, completely forgotten by modern science. He said to himself: physicists are explaining to us that at the basis of matter there are atoms and electrons, and microbes, when they come together, form multicellular beings, and his hypothesis, which was very avant-garde at the time, was that the mitochondria in cells are associated bacteria, that Golgi bodies are actinomycetes, and that all cellular compounds are in fact microorganisms associated with each other. Science has now proven that the DNA of mitochondria is very different from that of the cell; they multiply separately, and they seem to be beings that live completely in association with them. His idea was to search for these microbes, and he said to himself: ultimately, microbes are like atoms, they never die, they are eternal Life is maintained on the planet because when you die on the planet, you return to the microbial stage, and these microbes will re-associate themselves in another being... these are things that are somewhat reminiscent of Hindu religions. So he did an interesting study on limestone rocks: it should be remembered here that limestone rocks are of living origin, they were formed either at the bottom of the sea or at the bottom of lakes, by the sedimentation of micro-organisms and living organisms that accumulated and, under pressure, formed stones. He had fun taking these stones, grinding them up, putting them in Petri dishes, and realised that the microbes in the stones could be revived up to 170 million years later. This means that all the microbes on the Côte d'Or can be revived. This is very interesting, because it means that Burgundy vines, which grow in limestone soils rather than schist or granite soils, which have been heated to high temperatures and no longer contain microbes, will reawaken these microbes that have been there for millions of years and re-associate with them. It's absolutely fascinating, and we're starting to enter the realm of wine fiction!

• What about the hierarchy of terroirs? Are some terroirs more suited than others to producing great wines?

We know the climatic and topographical data, which are precisely defined. We also know the importance of the water regime. However, we had little information about the soil. Could we confirm the fact that the ancients had intuitively classified the terroir into grand cru, premier cru and AOC? My wife and I conducted a fairly detailed study of Burgundy. We were interested in seeing whether, mathematically, we could identify the characteristic criteria found in grands crus, premiers crus and AOCs. It turned out that, for reasons that were initially not related to viticulture but to agronomy, we were the first agronomic laboratory in France to take regular measurements of the internal surface area of clay. Clays are crystals in layers, parallel to each other, which have internal surfaces that can be measured. Clays around the world range from 10 m² to 800 m² per gram. It's a bit like tearing a book page by page... So it's a factor of 1 to 100, which is not insignificant. It turns out that this factor correlates very linearly and positively with cation exchange capacity. We were the first laboratory to use this to tell a farmer: your soil has a very high cation exchange capacity. There are two sources of cation exchange: humus and clays. Then one day, we said to ourselves: let's work on wines, and we realised that we had low internal surfaces for white wines and high internal surfaces for red wines. This analysis showed that in Bordeaux, the lowest internal surfaces were in Sauternes, and the highest in Pétrus and Médoc. We said to ourselves: if we want to come up with a scientifically valid criterion, we must not work in a region where there are several grape varieties, in order to avoid attributing the inevitable differences to the grape varieties alone. So we worked on Burgundy. My wife entered a huge amount of data. The statistical analysis was carried out by Florent De Vathaire, from the INSERM statistics laboratory, using linear discriminant analysis. What is remarkable is that we were able to classify the wines not only by colour, but also to separate the grands crus, premiers crus and AOCs. We can therefore say that what the ancients did in terms of classification corresponds to scientific soil analysis. This is a way of responding to the Americans who, at one time, said: "soil for wine is just bullshit" ... That is absolutely false: the soil is truly one of the important factors in the expression of terroir. From this perspective, all agricultural practices that advocate chemical weed control, thereby promoting erosion, contribute to the loss of clay because it is the clay that is lost in erosion. Winegrowers must therefore be made aware that if they allow their clay to be lost, they will lose the expression of their terroir. For the past 10 years, we have been trying to make winegrowers understand that soil is not just any old thing! It is part of their production capital and they must preserve it... We have created a soil classification index by studying the most famous terroirs. Conversely, this index makes it possible to identify new terroirs, i.e. terroirs that have been abandoned since the phylloxera epidemic, and to tell someone: here you can make a great wine or, on the contrary, here you must make a varietal wine – in other words, terroirs to be created.

What we need to do now is to get winegrowers to accept that there are places where you can make great wines and places where you have to make varietal wines. We have identified terroirs for whites and terroirs for reds, and people are making fine products that are recognised by tasting panels. Practice therefore confirms our theory. For example, we have worked on Switzerland, on regions such as Valais and the canton of Vaud. And we have shown that there are regions that deserve a hierarchy. For example, I was very surprised when I arrived in Valais and saw the schist soils. I thought they were acidic, but not at all, they are calcareous schist and there are indeed hierarchical levels of quality in Valais. There are large internal areas of clay and small areas, so we have to accept the idea that there is a hierarchy, otherwise we'll end up shooting each other.

• Have you carried out any analyses in the Côtes du Rhône?

Yes, for example, if we take the case of Côte Rôtie, we have the Côte Blonde and the Côte Brune, and we can see that the Blonde has a small internal surface area, while the Brune has a large internal surface area. So Viognier would be more suited to the Côte Blonde, while the Côte Brune is better for Syrah. Cornas, for example, has a small internal surface area, so it's more of a terroir for white wines. Tain l'Hermitage and Châteauneuf-du-Pape have large internal surface areas with more heterogeneous parts. Beaumes-de-Venise has a small internal surface area and is therefore best suited to white wines. If you take the Hérault, there is everything, from small internal surface areas to large ones. Cahors mainly has soils suitable for red wines, but also soils capable of producing great white wines.

• And outside France?

We are currently working on Italy. Personally, I'm not keen on the Tertiary soils of Tuscany, which are clayey mixtures with little character. On the other hand, Barolo and Barbaresco are extraordinary! These are terroirs with large internal surfaces. Italy's strength is that it has preserved 1,500 grape varieties and that, after having in the past sold rather poor wines in pizzerias, it is now undergoing a real rethink, and its extraordinary opportunity lies in the biodiversity of its grape varieties. There are many regions that can return to the concept of "terroir wines", Sardinia and Corsica spring to mind. And then there are regions that are less exciting from this point of view. I'm not passionate about the Côtes de Provence, except for Bandol, where we're not dealing with Alpine colluvial deposits but with terroir, we're dealing with metamorphism, it's really rock that is attacked by the roots.

• Among the emerging regions, which vineyards have definite potential for quality?

Hérault, Aude, Lot and Aveyron, for example. There is a completely dormant area that is superb, the whole area from Blois to Gien, the whole Loire area that has been abandoned – we mustn't forget that it was once the largest vineyard in France, supplying Paris – has great potential in the best exposures.

Anjou and Muscadet also have magnificent potential. The problem is moving away from cooperative farming, high yields, etc. I tasted some extraordinary Muscadets at Bossard, superb whites on schist. The same is true of the new vineyard that Grisard is creating in Savoie.

There is a real need to rethink things at European level, because Europe has an extraordinary opportunity to have its history shaped over the centuries, reflecting the adaptation of our vines to the terroir. This is a long process that we have somewhat forgotten, but which, over the centuries, has created areas for wheat, potato-growing areas, cider-producing areas and, of course, wine-growing areas. This history is fabulous and must not be wasted. This is how we will preserve the agricultural fabric of Europe. We must stop believing that we are going to compete with New World cereal farmers who work on 3,000 or 4,000 hectares. We must focus on craftsmanship. Moreover, I am not in favour of opposing terroir wines and varietal wines: each must have its place.

• Are there new terroirs to discover?

Not to discover, but certainly to rediscover. You can't make great wines on new soil. Vines are planted when the soil has been exhausted. Terroir is the result of a long tradition of cultivation, where the vines and the soil shape each other. The vines eventually create their own environment. To stay in Burgundy, for eight centuries the vines have produced their own clay and created their own specific terroirs. However, man thinks first of feeding himself before drinking. Burgundy was undoubtedly a land of wheat in Celtic times. To take more distant examples, there is a much greater chance of making great wines in Chile and Argentina, where Indian agriculture is found, than, for example, in Oregon, where the Indians were hunter-gatherers. Australia is a very interesting case because it is an example of a fundamental change in climate due to human activity: in just a few centuries, we have gone from a very humid climate to a very dry one due to intensive deforestation by fire. Australia's problem is that its grape varieties are unsuited to its climatic conditions. Southern grape varieties, such as Sardinian varieties, should be tried here. New Zealand has a cooler climate and it was right to plant Chardonnay and Sauvignon there, but it is a "new" region in terms of wine production and I don't think it will be possible to make great wines there straight away.