Ampelos (Vine): Time for Terroir?

'Terroir': Is There Some Truth in Every Myth?

Abstract/overview: The word and concept of "terroir" has come to represent winegrowing traditions and beliefs, some of which date back 7,500 years to explain how grapevines grow, what wine contains and why it tastes the way it does. Adherence to such beliefs (acceptance of something as true or real) and myths (widely held tradition, story, exaggerated or false belief) to explain winegrowing (the growing of grapes and finishing them to wine) prevents and/or hampers objective and open-minded investigation of grapevine physiology and wine sensory analysis (Matthews, 2015). Recently, "terroir" has been used as a marketing ploy (especially following the 1976 Paris wine tasting at which French judges determined that California wines were superior to French wines, in a blind side-by-side comparison). This essay provides a case study and peer-reviewed research into the effects of selected elements of "terroir": climate, soil , yield and vine spacing on grapevine performance. An application of sensory science, called 'descriptive analysis', used to explain how wine is perceived, is also presented.

A working definition:
Terroir (“tair-wahr”): an ecosystem, in a given place, including many factors including: climatic conditions, cultivar and rootstock, geography and topography, soil characteristics such as mineral nutrition and water supply (Seguin, 1986)

In contrast to the Seguin's definition, many who try to explain or apply 'terroir' often resort to complex, contradictory, subjective opinions, relying on tradition, unsubstantiated intuition and antidotal observation. Since the 1300's, winegrowing Cistercian monks in Burgundy, France have been credited with the concept of terroir as a 'sense of place' that imparts uniqueness and 'quality' to a wine form a specific region or vineyard (Patterson and Buechenstein, 2018). But is 'terroir' a 'sense of place' or a concept, a culture, a soil-based production system, a marketing ploy or all of the above? Whatever it is, many winegrowers, writers, critics, sommeliers, marketers and consumers 'believe in it' and embrace it (Morris, 2018). Thus 'terroir' seems the antithesis of empirical science and many viticulture scientists's view of it is summed up in quote from Dr. Marcus Keller or Washington State University: "... the concept of terroir is mostly meaningless, because something that explains everything (in one word!) ends up explaining nothing." Nonetheless, many consumer attitudes and their wine purchases are based on a language of 'terroir'.

When one Googles the word 'terroir' many articles surface that provide many general 'terroir' categories, such as climate, soil, topography, grapevine genetics, human culture, and the microbiome of fermentation. Faced with these myriad factors, it is convenient to break 'terroir' into two broad realms: the physical, or vineyard site characteristics, and the sensory aspect of wine from a given site, Zoecklein (2019). Physical site characteristics with assigned numeric values, calculated as 'natural terroir units' (NTUs), are used in some wine regions to assign value or rank to vineyard sites and their wines (Table 1). From the NTU list we consider: climate, soil and yield. Both climate and soil have been amply documented to drive all vine performance (Jackson and Lombard, 1993) and yield is important across all agriculture endeavors.

Although climate is presented as single entity in the NTU listing, as it affects agriculture, inclusive of vineyards, climate is best understood on three levels (Figure 1): ‘microclimate’, the climate within the grapevine canopy (or any plant canopy), ‘mesoclimate’, within a particular vineyard, farm or agronomic field and ‘macroclimate’ or regional climate, categorized as either maritime or continental (Geiger, 1927, as cited in Patterson and Buechenstein, 2018).

CATEGORY ‘Natural Terroir Unit’	MAXIMUM VALUE
Location	600
Aspect	250
Altitude	150
Gradient	100
Soil	100
Microclimate	60
Varieties	150
Vine age	60
Vine density	50
Yield	150
Maintenance	100

Table 1. Physical parameters or Natural Terroir Units (NTUs), used to classify a vineyard site’s ‘terroir’ and the wine it is likely to produce. Adapted from, Carey (2001).

Figure 1. Three levels of climate impacting plants/grapevines.

Next, lets briefly consider soil and its role in ‘terroir’. Notice that within the NTU list (Table 1) ‘aspect’ (compass direction) is ranked over soil, despite soil's geology and proven agronomic impact on most all agricultural crops. However, Van Leeuwen et al. (2004), elegantly investigated ‘terroir’ in Bordeaux, France by comparing yield and berry composition of three vineyards, all exposed to a similar climate and the planted to the same cultivar, Cabernet Franc, but, each having a distinct soil type (Figure 2). Van Leeuwen et al. found that the soil’s water holding capacity, contingent on its texture, was the factor with the greatest effect on vine vegetative growth that indirectly impacted berry composition, and finally, the wines from each site. In another soil-centric study in Australia, withholding irrigation water pre-fruit-set to veraison (onset of ripening: grapes soften and develop color, flavor and aroma), restricted vine uptake of nitrogen, and improved berry composition without significantly reducing Brix level (sugar %) or yield (White et al., 2007). Unsurprisingly to agrarians, these studies showed that water and its availability dependent on soil type, along with the mineral nutrient, nitrogen, are the main drivers of plant growth, including grapevines. These two components influenced by the vineyard soil, invariably and substantially, impact the physical realm and result of ‘terroir’.

Figure 2. Percentage of clay, loam, sand and gravel in the root zone of (A) gravelly soil, (B) clayey soil and (C) sandy soil. (Van Leeuwen et al., 2004).

Next within the NTU list, consider that yield is assigned greater weight than ‘maintenance’, i.e., all viticultural operations: pruning, leaf removal, trellis design, fertilization, cultivation, cover crops, irrigation, and spraying. This ranking of yield over maintenance, is interesting in light of the widely cited and classic paper by Jackson and Lombard (1993), who review and explain the impact of site and viticultural operations, i.e. ‘maintenance’ on grape composition and yield, without mention of the word ‘terroir’. To this point of maintenance or cultural impact, Dr. Mark Matthews, (2015) presents several ‘terroir’ ‘beliefs’ that he classifies and explores as ‘myths’ and then systemically debunks. One of these myths is: ‘high yield equals low quality’ and its accompanying tenet: many small vines with a small yield is superior to few large vines with greater yield.

I have first-hand experience with this ‘tenet of terroir’. As a vineyard consultant working in the humid, southeastern US, I was presented with a vineyard planted to a ‘high-density’ European model, with meter x meter vine spacing and ~ 4,400 vines/acre. Research based recommendations for the eastern US at the time, were for a much wider row and vine spacing, with ~ 800 to 1000 vines/acre. The high-density planting presented problems: increased fungal disease, low yields, poor quality fruit (reduced light exposure and increased bunch rot), increased labor for: canopy management, mowing, spraying and harvest as ‘normal’ tractors could not navigate the ~ 39 in. rows (Figure 3).

Figure 3. Meter x meter vineyards: Chablis France (left) and North Carolina, US (right).

It was not my personal opinion, but peer-reviewed research (Intrieri and Filippetti, 2000) that informed my recommendation that two thirds of the rows, and every other vine within a row be removed, to achieve a ~9’x 6’ spacing and ~ 840 vines/acre. Fewer vines/acre actually increased yields (from 1 to 2 tons/acre the next year) and quality, reduced operating costs, and refuted the low yield = high quality ‘belief’. Obviously, this one case study does not explain the entire concept of ‘terroir’, but it did shed a degree of empirical light on one aspect of it…in that one place.

The second realm of ‘terroir’: sensory impact, has relatively recently been explained beyond the subjective, in a classic paper by Dr. Ann Noble, the first woman food scientist at UC Davis. Dr. Noble applied descriptive analysis and comparative statistics to compare and differentiate wines (Noble et al., 1984).

Term	Composition of reference standard
Berry (black/raspberry)	10 ml liquor from canned blackberries, 2-3 thawed frozen raspberries, 5-6 g strawberry jam, 5-6 g raspberry jam
Black currant (canned/ “Ribena”)	7-10 ml liquor from canned black currants, 2-4 ml Sainsbury’s black current drink
Synthetic fruit	5 ml cherryade (Corona drinks), 1 pear drop
Green bean/green olive	4-5 ml liquor from canned green olives, 8-10 ml liquor from canned green beans
Black pepper	4 particles black pepper (fine ground)
Raisin	10 raisins
Soy/ “Marmite”	0.5 ml soy sauce, 0.5-1 g “Marmite” yeast extract
Vanilla	0.25 ml vanilla flavoring essence
Phenolic/spicy	5-10 ul 4-ethyl guaiacol
Ethanolic	5 ml (950 ml liter^-1) ethanol

Table 2. Aroma terms selected for the descriptive evaluation and composition of the reference standards created to define them (Noble et al., 1984).

Descriptive analysis protocol required that a trained a panel of tasters assess (describe) the wines (24 wines from four different Bordeaux producers) using commonly discovered and agreed upon aromas and flavors, benchmarked with common ‘reference’ standards (Table 2). The wines’ quality was further compared by certified Masters of Wine (MW). The major differences between the wines was in variation of the intensity of the ‘green bean/green olive’ character and astringency and bitterness by mouth, determined by canonical variates analysis (CVA). The wines did not differ between producers and MWs were unable to differentiate the wine’s quality.

Recently, wine writers and critics have taken to describing a ‘direct connection between wines and their terroir’, via the flavor descriptor referred to as ‘minerality’ (Maltman, 2013). Despite the physical difference between mineral compounds that occur in soil, and mineral nutrients that occur in grape juice and wine, many wine writers and winemakers, claim to taste the vineyard soil in wine. A wine’s ‘minerality’ is not only ‘detected’, but celebrated! What exactly are they tasting? For example, if the mineral nutrients of potassium, calcium or sodium actually occurred at levels within the human sensory threshold and thus, were detectable to the palate, they would likely be toxic! In this instance ‘minerality’ is a subjective descriptor, not an actual measurable factor. ‘Minerality’ may well exist…however, it is just not the case that actual mineral compounds are absorbed by the vine’s roots, transported to the grape berries, directly deposited in one’s wine glass and consequently are available and tasted as ‘minerality’ (Maltman, 2013). ‘Minerality’ then, as a descriptor, appears well-positioned to occupy the tension between the physical and sensory realms of terroir and that of unsubstantiated beliefs.

Obviously, there is something going on with winegrowing, wine consumption and “terroir”. Terroir’s factors, as defined by Seguin at the beginning of this essay, can be investigated and measured, wine is an agricultural product after all. However, few agricultural products have gods dedicated to them, as provided by the Greeks and Romans. There remains something unexplained about a wine’s ‘terroir’, something akin to Chinese acupuncture, or Polynesian ocean navigation, each of which is documented to actually ‘work’ (Patterson and Buechenstein, 2018). ‘Terroir’ as an overarching explanation of winegrowing seems to ‘work’ for many…and to those of us who doubt, question, test and document…it extends an invitation of exploration and discovery into what makes grapes transformed to wine so unique and special to us.

References:

1. Carey, V.A., 2001. The Spatial Characterization of Natural Terroir Units for Viticulture in the Bottelaryberg-Simonsberg-Heiderberg Winegrowing Area. MS Thesis, University of Stellenbosch.

2. Intrieri, C., and I. Filippetti. 2000. “Planting Density and Physiological Balance: Comparing Approaches to European Viticulture in the 21^st Century.” Proceedings of the American Society of Enology and Viticulture 50^th Anniversary Annual Meeting, June 19-23, 2000 Seattle, Washington, 296-308.

3. Jackson, D. and P. Lombard. 1993. Environmental and management practices affecting grape composition and wine quality—a review. Amer. J. Enol. Vitic. 44: 409-430.

4. Maltman, A. 2013. Minerality in wine: a geological perspective. J. Wine Res. 24:169-181.

5. Matthews, M. 2015. In, Terroir and Other Myths of Winegrowing., Univ. of Calif. Press, Oakland, CA.

6. Morris, R., 2018. Does terroir matter? https://www.winemag.com/2018/11/13/does-terroir-matter/

7. Noble, A.C., A. A. Williams, and S.P. Langron. 1984. Descriptive analysis and quality ratings of 1976 wines from four Bordeaux communes. J. Sci. Food Agric. 35:88-98.

8. Patterson, T. and J. Buechsenstein. 2018. In, Wine and Place., Univ. of Calif. Press, Oakland, CA.

9. Seguin, G. 1986. ‘Terroirs’ and pedology of vinegrowing, Experientia, 42:861–873.

10. Van Leeuwen, C., Friant, Ph., Chone, X., Tre’goat, O., Koundouras, S. and Dubourdieu, D. 2004. The influence of climate, soil and cultivar on terroir. Amer. J. Enol.Vitic., 55:207-217.

11. White, R., Balanchandra, L., Edis, R. and D. Chen. 2007. The soil component of terroir. J. Int. Sci. Vigne Vin. 41: 9-18.

12. Zoecklein, B. 2019. What defines your wines? Wine Business Monthly, Dec. 62-69. www.winebusiness.com

Sunday, October 18, 2020

Time for Terroir?

'Terroir': Is There Some Truth in Every Myth?

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