The truth about terroir

If there was a theme to this year’s Wine and Food Festival at the Fairmont Banff Springs Hotel, from which my wife and I just returned (feeling very well wined and dined indeed, thank you very much) it was terroir.

Terroir is a French word which has no English equivalent (and the French like it that way). At Banff, Ruth Souroujon, vice-president of marketing for Kendall-Jackson Wine Estates, defined terroir as “the total natural growing environment of any viticultural site that allows a grape variety to uniquely express itself.”

Winemakers’ focus on terroir makes sense when you realize that the idea that the same grapes grown in different locations result in different-tasting wines is central to the entire wine industry. If there were nothing to terroir, then all wines from one region made from one particular grape would be indistinguishable from wines made from another region from the same grape—and people would pay as much (or as little) for Generic Red in a Jug as they do for Chateau Petrus.

Oddly enough—or not so oddly, if you’ve ever heard the near-worshipful way some people talk about wine—being scientific about terroir is controversial. Jamie Goode, author of the recent book Wine Science and holder of a Ph.D. in plant biology, says some people see terroir as a philosophy, as “a unifying theory encapsulating a certain approach to wine that encompasses the almost metaphysical circle of soil, nature, appellation and human activity.” But Goode, being scientifically minded (as am I) prefers to strip away the philosophy and focus on the scientific reasons the same variety of grapes grown in different plots of land taste different from each other.

In a Harpers Weekly article in September, 2003, he explored the “mechanisms of terroir.” He pointed out (and I think I heard some talk like this at Banff) that there is a long-standing belief among some winemakers that the mineral content of a vineyard’s soil affects the flavor of the wine made there: i.e., flinty soils impart a flinty taste, chalky soils impart a chalky taste. Goode (and the experts he consulted) found this implausible, to say the least.

Indeed, a French (yes, French) scientist, Gérard Seguin, surveyed the properties of soils in the Bordeaux region and could find no reliable link between chemical composition and wine character or quality. Instead, he found a connection between soil drainage and wine quality: the best terroirs, he found, were the ones where the soils are free draining, with water tables high enough to ensure a regular supply of water to the roots up until the time the berries change color (called veraison). After that, ideally, the water recedes, so that the vine stops growing and concentrates on ripening its fruit.

It’s possible, Goode pointed out in his article, that tiny variations in the minerals available in the soil affect the expression of certain genes within the plant, which might indeed impact the final flavor of the grape, but that’s a far cry from “a flinty taste comes from flinty soil.”

Soil type may affect grape growth in another way: dark soils retain heat and radiate it at night, while light soils reflect heat and sunlight immediately back onto the vines but don’t retain as much heat at night. Those effects would tie in with the overall microclimate of the vineyard, which varies with altitude, orientation and geography, and also affects the growth of the grapes.

The best way to get a feel for the effects of terroir is to taste several wines made from grapes grown on different plots of land but vinified by the same winemaker. Which is exactly the exercise Soujournon led us through at Banff: we tasted five Cabernet Sauvignons, each made from a specific plot (at altitudes from 401 to 2,204 feet above sea level, with varying aspects and varying kinds of soil), and then attempted to blend our own equivalent to Kendall Jackson’s signature (and quite expensive) Grand Reserve Cabernet.

I thought my resulting blend was quite successful, though alas I was not allowed to pour it into a bottle and sell it.

The exercise convincingly demonstrated that terroir—the scientific version of it—really does make a difference. It may not be as simple as the soil directly imparting flavors to the grapes, but considering Ontario’s Ministry of Agriculture, for one, suggests the spring application of manure to vineyards, that’s probably a good thing.

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