Terroir and the Côte de Nuits

Abstract

Within Burgundy, qualitative differences between wines are ascribed to terroir, even though the relationships between the variables that constitute terroir are rarely articulated. The production of red Burgundy has been, and continues to be, deeply personalised, and terroir boundaries have relied upon human judgements of value and taste for their establishment; borrowing from Goethe, their existence is testament to the operation of a ‘tender empiricism’ across the centuries, rather than the pursuit of antecedently agreed criteria. Recent studies in viticulture have established how berry composition and morphology are influenced by a range of environmental factors, physical, chemical and biological and an understanding of these interactions further supports the attribution of terroir to the Grands Crus vineyards of the Côte de Nuits.

Whilst standing above the Grand Cru village of Avize, François Billecart joked with me that the best vineyards in France all face Germany. The Côte de Nuits and the Côte de Blancs were obviously on François's mind, and not Chablis, the Rhône or Bordeaux. However, even within the boundaries of Champagne the vineyards didn't support his suggestion: the chalk falaises of Aÿ and Ambonnay fall south; and the magnificent Verzenay looks north over open plains, its chilly aspect adding to a sense of climatic foreboding that builds around vintage time.

Contrary to M. Billecart's assertion, the usual presumption is that south facing slopes are advantageous in temperate northern climates. The precipitous valley sides of the Mosel are the perfect example, the steep slopes gathering in the warmth of a weak sun at the beginning and end of each season. So pervasive is this idea, that writers will often force the facts to fit the theory. Some comentators have attributed the pre-eminence of Romanée-Conti within Burgundy to its southeasterly exposure, when it does in fact face due east. Whilst acknowledging Romanée-Conti's correct orientation, Clive Coates has commented that the vineyard receives more light than adjacent vineyards; and Robert Parker claims it occupies the steepest part of the Vosne hillside. Having cycled from Santenay to Fixin, I can't recall the tame gradient of la Grande Rue being the freewheeling slide back into Vosne that Parker's ‘Burgundy’ book had prepared me for.

The Côte de Nuits has two fundamental elements: a pixel-like plan of vineyards that seems more maze than map; and a grape variety, pinot noir, that rather than simplifying things, just seems to make matters worse: a sort of mystery within a mystery. Running between Gevrey Chambertin and Nuits-St-Georges is the Route des Grands Crus, which might sound like the road to Xanadu, but as with most things in Burgundy, it's weathered and worn. Of the two Grands Crus that make it far enough down slope to meet with the region's main road, the RN 74, it is Clos Vougeot that throws up the biggest antinomy: how can the width of a two-lane road be sufficient to separate out vineyards at the top and bottom of the Côte d'Or's hierarchy? Surely the weather, let alone the climate, must be the same for both sides of the road! On my first visit to Burgundy, parked-up against the gates of Clos Vougeot, I was left to ponder the inequities of the appellation system; the incoherence of terroir, and why the past was deemed so much mightier than the present by those that toiled around me?

Burgundians have a strong attachment to tradition and history. The gently ruining walls and arches that separate the Côte d'Or's vineyards may seem like the relics of a fallen civilisation, but they are the enduring legacy of a ‘tender empiricism’ that stretches back millennia. Terroir for the current occupants has become a kind of faith: something to be believed in rather than proved. If wine writers occasionally stray into hyperbole when they're forced to separate a Clos de Bèze, say, from a Chambertin, then there is a redress of sorts in the succinctness of the vignerons themselves attributing all differences to terroir. It is always that same one-word validation. Those looking for more elaborate explanations will have to look beyond Burgundy, past its wines and growers, for illumination.

Using a statistical technique known as principal component analysis, Franck Wittendal1 recently compared the vineyards of the Côte d'Or in order to determine if there was one factor that was exclusive to the Grands Crus. He found that altitude, aspect, parent rock, convexity and gradient were not significant in separating out the Grands Crus from the Premiers Crus, Villages and generic wines; but soil structure was. Statistically what distinguished the red Grands Crus from the rest of Côte de Nuits' vineyards is the high proportion of gravely, colluvial hillwash in their sub-soil. Wittendal's study built on observations made previously by both Gadille2 and Seguin3 about the aggregate composition of Burgundy's soils, but his statistical analysis gave this feature a much greater significance than had their earlier works.

Burgundy's geology is complicated. The alternating depositions of calcareous clay, marl and limestone were faulted, as the Côte d'Or came to form one side of a rift valley. Over a few metres, the soil can alter from coarse colluvial to plough-friendly alluvial, and back again. Vineyard names like les Perrières, les Argillières, and les Ruchottes flag the changes. Nowhere is the distinction more apparent than Vosne, where the land at the front and back of the village is profoundly different. When growers in Chambolle and Morey bemoan the respective quality and prices of their village wines versus those of Vosne, they might well be onto something.

Soil is the plant's main source of nutrition and water, and vines are in their element when both are in plentiful supply: long shoots, plate-sized leaves and thick trunks are the plant's preferred way of being. If we want to divert the vine's resources towards reproduction, and away from enlargement, then some restriction on water and nitrogen availability, either naturally or imposed, is necessary.4

The competition between the vine's organs and vessels for sugars formed within the leaves changes throughout the season; but it also changes in response to fluctuations in water status. Water stress will impede vine respiration, but a slight deficit between flowering and veraison will keep fruit small and accelerate its maturation.5 Conversely, unrestricted access to water and good nitrogen nutrition will slow down the ripening process and yield large berries. Deficit conditions are obviously advantageous in a marginal red wine region like Burgundy, promoting maturity whilst at the same time beneficially increasing the ratio of skins to juice; but one can also see how a less limiting regime might be useful to sparkling wine producers, who favour low levels of phenolics for their delicate base wines.

The stony soils of the Côte de Nuits' Grands Crus fit in nicely with this theory. The limestone bedrock endows the soils with abundant levels of elemental calcium, way beyond the needs of the vine, together with its ion, calcium carbonate. Calcium helps open up the capillaries in the soil, increasing porosity and assisting root colonisation.6 Flocculated clays have the physical properties of sand, whilst still retaining their nutrient holding capacities. A high percentage of stone fragments adds to the drainage capability of the soil, but reciprocally, these same fragments are a supplemental source of water that the roots can draw upon during times of shortage. Both water stress and water surplus can delay the onset of grape maturation, and the Grands Crus' load of small, porous stones helps buffer the vine against both eventualities, favouring the early maturation of small-berried bunches.

In places, the Haut Médoc's geology of sand and gravel seems scarcely to have evolved beyond that of the nearby Atlantic beaches, but the same principle of water rationing applies. Through the summer, a retreating water table strands the vines, lowering their water status, and encouraging an early veraison of small-berried clusters. The impermeable pebbles of the Médoc are without the water holding voids of Burgundy's limestone fragments, but in the better vineyards clay lenses running through the soil horizon fulfil the same buffering role. Of the two vascular tissues that run within the vine, the phloem and the xylem, it is the latter that pumps water from the roots to the shoots, leaves and bunches. Prior to veraison the xylem flows freely, and there is a strong correlation between soil moisture and berry size. During the post-veraison period, however, the efficiency of the xylem flow into the berries becomes severely disrupted,7 and the direct link between soil moisture and final berry size is broken. Most discussions about vintage look at the weather in the run into harvest as the true indicator of potential quality, but the weakening of xylem flow after veraison means that for red wines at least, a more season long perspective of soil moisture conditions might prove beneficial. In particular, was soil humidity before veraison sufficiently low enough to impact berry size?

Vine water status can favourably alter berry morphology, but better wines are made when the individual berries within the bunch ripen synchronously, and here, too, soil can play an important role. The success of flowering, the fertility of inflorescences and the progression through to fruit set, depends in a large part on the availability of carbohydrates within the vine at that time.8 In Burgundy, floraison usually occurs in early June, by which time each shoot should have about 17 or so leaves in various states of unfurling, all cascading down from a vigorously growing shoot tip. Despite the fact that green growth is already filling the trellis wires, the competing demands of the flowering clusters, the expanding leaves, and the shoot tips stretch the vines limited resources.9 Much is made of the weather at flowering impacting on yield. Leaves, even at this early stage of the season are a vital source of carbohydrates, but only the basal leaves are mature and large enough to contribute to the vine's needs in any significant way. The efficiency of photosynthesis is improved by sunshine and warmth, and is compromised by cool, overcast conditions. In the warmer parts of the New World, long, sunny days will nurture the vine through flowering, but at the margins of production, in Champagne, Tasmania, Burgundy, New Zealand and England, unsettled weather will lower both cluster fertility and fruit set, whilst prolonging flowering so that ripeness in the bunch becomes more irregular. Under these circumstances, the vine can mobilise its own starch reserves to help supplement any shortfall between carbohydrate production and demand, and the magnitude of these reserves relative to the scale of any deficit may well improve the homogeneity of bunch maturity right through to harvest. The roots are by far the most important store of starch, reserves being carried over from one season to the next, and a high ratio of roots to shoots will modify the source/sink relationship within the vine, effectively decreasing the reliance on seasonal photosynthesis to satisfy the competing needs of the grape clusters and the shoot tips. Friable soils do not offer the same resistance to root growth, as do heavy, clayey soils. Furthermore, should these soils routinely dry out, if evaporation loss is periodically greater than precipitation gain through the growing season, then conditions will stimulate dense root colonisation. The resulting compact network of rootlets will not only nourish the vine with nutrients and water, but they will also double as stores for starch. Within the Grands Crus,10 the overall rooting volume is restricted both vertically, by bedrock, and horizontally, by competing vines, but the combination of high stone loads and elevated calcium concentrations modify soil structure in such a way that dense rooting patterns result. Consequently, the Grands Crus may well have an advantage over lesser appellations in the starch storage capacity of their vines, a benefit that may ultimately deliver more even ripeness within the bunch at harvest.

It follows from the above, that in cool, cloudy regions, viticultural practices that lower the ratio of shoots to roots may have implications for the potential yield and quality of the crop. Humid soils, or excessive irrigation, could result in a relatively small, undeveloped root system. A plentiful and easily accessible water source will not encourage the vine to root with any vigour, which will then have a knock-on effect on its capacity to store starch across the seasons. Similarly, large bud numbers per vine will put huge demands upon any available reserves. Either way, there will be an over-reliance on seasonally produced carbohydrates to satisfy the needs of the rapidly growing vine. There has been much agonising over yield variation in Tasmania, but the combination of large vines, late picking and irrigation may well be exaggerating the effects of poor spring weather. New Zealand has a similar adherence to big vines and irrigation, and is frequently subjected to less than ideal meteorological conditions during flowering. Could it be that prolonged flowering is impacting the homogeneity of bunch ripeness? And is it not one of the traits of many New Zealand pinot noirs that the same glass of wine simultaneously exhibits both fruity and vegetal characters?

It was Mark Twain who wrote: “Climate is what we expect, weather is what we get.” Annual rainfall for Dijon is around 700 mm, but distribution across the summer months seems increasingly erratic. As mentioned above, high soil humidity invigorates the vine, whilst drought conditions compromise its metabolic efficiency; the ideal conditions are those that keep vine water status low, whilst avoiding stress. The stony soils of the Grands Crus therefore play a crucial role in hydric-ally buffering the vine from the inherent variability of ‘weather’; rather like the way in which the potential energy of a wound clock is dissipated through springs, spindles and cogs into the barely perceptible movements of the hands.

Burgundy's climate has many moods, less a regime and more a meteorological mishmash of sub-alpine, maritime, continental, and Mediterranean influences. But the risks of hail, frost and rot do not obscure the climates overall affinity with pinot noir. Arguments as to the origins of pinot noir are not conclusive. It has been suggested, quite seriously, that pinot was native to Burgundy before the arrival of the Romans, and that its northern provenance is shown through its intolerance of hot weather: as the temperature approaches 30°C, carbohydrate synthesis slows dramatically. The easterly orientation of the Côte de Nuits is compatible with this theory insofar as its slopes intercept the afternoon sun obliquely and therefore avoid the heat-spikes that occur in southerly and south westerly facing vineyards. Moreover, as unreliable as spring can be in the Côte d'Or, through July and August mean daily temperatures between 18 and 20°C put the vines in the sweet spot for carbon accumulation, and the period from fruit set to veraison is correspondingly short. By September, however, mean temperatures and day length are spiralling down. The Gulf Stream may have hoisted viticulture high into the eaves of the French l'Hexagon, but a rapidly weakening sun can't stem the creep of autumn. By early October, the first frosts have felt their way into the vineyards.

The Australian viticulturist Erland Happ urges that we pay close attention to ‘heat loads’ post-veraison when assessing potential vineyard sites, or when judging a particular vintage's quality.11 The period between veraison and harvest is not fixed, but traditionally on the Côte de Nuits the month in which maturation was concluded was September. According to Happ, after veraison berry skins become softer and more porous. Most growers, particularly those who tend shiraz, are familiar with the notion of berry-shrivel, as the clusters dehydrate at the end of the season, but Happ claims this is also a period when flavours become ‘fugitive’ too.12 Warm temperatures, which Happ defines as anything above 22°C, encourage the loss of flavour compounds, many of which have a lower molecular weight than water. This is not to say that grapes grown in warm climates are without flavour, rather they can be qualitatively different to grapes grown under a cooler end-of-season regime. In particular, it is the delicate, more floral flavours, like the violet-scented nonrisoprenoid, beta-ionone in pinot, which seem most vulnerable.13 Remember, too, that pinot's thin skins offer much less protection to a combination of high heat and light irradiance than does a thick-skinned variety like cabernet sauvignon. Happ concludes that no variety benefits from high heat loads in the month before harvest, though it goes without saying that there has to be sufficient light and warmth to maintain sugar production and enzymatic activity. In this regard, Burgundy's September mean temperature of 16°C is about perfect, though we need to keep reminding ourselves that climatic means are aggregated out of weather.

Pinot is in this sense the Goldilocks grape, liking things neither too hot nor too cold to show at its best. However, the villain in this tale is often humidity, which can abruptly bring a vigneron's vintage aspirations crashing down. Just as the Burgundian climate finesses temperature thresholds, so its vines benefit from the high relative humidity of its mid-latitude location, even though the struggle with fungal disease has become something of an annual dogfight with Nature. All things being equal, high humidity will mitigate against the vaporisation and loss of low molecular weight flavour compounds.

I claimed earlier on that there was a crucial distinction between low vine water status and hydric stress. The former doesn't compromise vine metabolism but directs the vine's resources preferentially toward seed and fruit ripening, and away from vine growth and shoot elongation. What is so fascinating about the Burgundian climate, and the interplay between pinot noir and the underlying soil conditions, is that in the best vineyards, low vine water status is achieved under climatic conditions that are remarkably humid. By contrast, vineyards in Chile's Casablanca Valley and New Zealand's Cromwell Valley depend on irrigation for their very existence; whilst the combinations of low relative humidity and high irradiance that both regions experience, introduces an element of stress into the fruiting zone that may have questionable benefits in a variety as sensitive as pinot. The Grands Crus of the Côte de Nuits are exceptional because they can balance the vine's water and nitrogen status on the low side of moderate, whilst the fruit itself hangs and ripens in a benign environment that favours flavour retention.

Man is the third element in the terroir model. Soils need managing: nutrient levels must be amended as they are taken up by the vine, or leached away from the root zone; and organic material needs to be balanced against clay and calcium carbonate content. Moreover, viticultural practices can provide another buffer against the vicissitudes of weather. Notwithstanding the above, given the heterogeneity of the soils of the Côte de Nuits, perhaps we should be surprised at how a grid of 1 m x 1 m planting, with its concomitant six to eight hedged shoots per vine is so prevailing. There is, of course, a very practical explanation for this: Burgundy is not a start-up; vine age is valued and new grafts are only used to replace dead or diseased vines. Yet, few Burgundians get excited about viticulture; for most it is ceteris paribus: the constant variable in a quasi-experiment that is designed to show how variations in soil and subsoil ultimately impact wine quality. Just how deeply this attitude runs through the local vignerons was brought home to me by a conversation I had with a young winemaker in the Côte de Nuits. His first vineyard purchase was a generic Bourgogne vineyard. Immediately he set about heightening the foliage wires, to increase the ratio of leaves to fruit, and through the summer he fastidiously stripped away leaves from around the fattening bunches. Harvest arrived, and in an indifferent year, his Bourgogne Rouge was concentrated and colourful, easily absorbing all the oak tannin and flavour from the new barrels in which it was reared. At six years of age, the wine still showed well, quite unlike any Bourgogne I have ever tasted. And this was the problem; well, at least it became a problem for his esteemed neighbours in the village. “This is not Bourgogne Rouge,” they intoned. “If you want to make a powerful wine you must buy land in Vosne.” Which he did. Yielding to their criticism, the trellising came down, and his viticulture became much more orthodox. Tasting his latest wines was pleasurable, they still out-performed their respective appellation status, but I left wondering how much better they might have been if he had continued to follow his own curiosity rather than the manacled prescriptions of his neighbours.

This inauspicious sounding tale brings me back to the frustrations of depicting ‘terroir’ as something ineffable and beyond description. If anything still proves to be beyond the predictive power of man, then it is, as Mark Twain reminds us, the weather; so we should hardly be surprised that the best terroirs effectively buffer the vine from its excesses, quantifying over individual cloud bursts and droughts and delivering them into a regime that, at root level, more closely resembles the smooth curves and plotted trends of climatic means.

The discussed association between soil hydrology and berry morphology, together with the account of roots' inter-seasonal starch storage capabilities does, I hope, go some way to explaining how terroir acts upon pinot noir grown on the Côte de Nuits; but this study is by no means exhaustive. A more thorough examination would include a description of how the production of stilbenes, a vine's natural fungal inhibitors, are promoted by elemental calcium; and I have dodged the issue of how particular flavours seem allied to particular cru, mainly because even bunch ripeness and berry size alone might account for most of the observable differences between wines (expressions of quality being a narrative on variances in quantity). Similarly, man's involvement extends beyond viticulture into wine making, when the fruit's inherent qualities can be selectively exaggerated or subdued. This latter thought brings me back to M. Billecart, standing on the hillside at the back of Avize. Champagne is a very manipulated product. The prise de mousse, the second fermentation and maturation on lees, marks that long period when the style and personality of the wine changes from hidden and brooding to brash and festive. When I asked what remains of terroir after the tumult and rest of the méthode champenoise, Francois obliquely replied that one must always be able to taste back through the wine to its origins. The vintage will dictate the broad parameters of ripeness, but when it comes to the wine we also need to be able to taste the precision that good terroirs donate.

Notes

See Wittendal (2004).

See Gadille, ‘Le Vignoble de la Côte Bourguignonne’, quoted Hanson (1972: 55–71).

See Seguin (1986).

See Archer and Hunter (2004).

See Matthews et al. (2006). Matthews et al.'s slogan about viticulture: “It's not the destination, but the journey that matters” makes the point that most attempts to curb vine vigour, or reduce berry size are flawed: resulting in vegetal wines. The benefits of small berry size and small crops are only attained if the vine's crop is naturally balanced at these levels.

See Saxton (2002).

See Bonarda et al. (2005).

See Lebon et al. (2008).

Assuming a trellis of Burgundian proportions, that is, 80–90 cm shoots.

The Grands Crus are not homogenous in this respect. Soils in les Bonnes Mares and le Musigny are shallower than those of Richebourg and la Tâche, for example.

See Happ (1999a) Wine Industry Journal Vol4, no.4. Happ extends work by John Gladstones, which he summarises as “the leaky bucket theory”.

See Happ (1999b).

See Dry (2009). Dry thinks we have gone too far with bunch exposure in all but the coolest and cloudiest of climates.