Busting terroir myths: The science of soil and wine taste

Carole Meredith tagged this article, which is quite an interesting read:

Busting terroir myths: The science of soil and wine taste
Professor Alex Maltman December 20, 2018

Professor Alex Maltman questions the new orthodoxy that vineyard geology is of overriding importance to a wine’s character, and highlights some factors that may have been overlooked when it comes to understanding wine terroir in the glass.

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Thanks for that link, Alan. Very nicely done article, though nothing all that new to you & me.
But it’s a subject that more people should be aware of.
The big take-away from the article for me was the importance of the root-stock in the vines pick-up from the soil,
something I’d not thought much about. But the vine simple regulates the the nutrients it pulls out of the soils and doesn’t
have kidneys/livers like humans to reject as waste what is not needed. And it’s the rootstock that regulates those up-take
decisions, not the vine up-top.
Nice to see you up at Carlisle the other day.
Tom

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A very clear, concise and polite debunking. Very informative.

Two things I would wonder about, though:

  1. While it’s easy to use hard science to dismiss anecdotal observations (and very often proper), I give some credence to people of the land like vignerons who have tended the same vineyard for decades (or generations) and have noticed differences in the wines that are made from different parts of the same plot that have different geologies.

  2. This focuses on chemistry and geology and may not sufficiently account for more complex biological factors that may be affected by geology and, in turn, affect the resulting wine (e.g., organisms in the soil).

Put another way, you don’t have to believe that the minerals in the soil are reflected in a wine’s taste (which doesn’t seem to hold up to analysis) in order to suspect that geology has a significant impact on wines. If geology were irrelevant, I guess we could just grow everything hydroponically.

Yup, John. Agree. In the last paragraph, he refers to the unknown effects of the microbiology in the soil and much more research on that being needed.
Tom

Thank you for sharing, Alan. As others have said, it is a nice to write an article that certain debunks some of the conventional wisdom is thrown out there by the wine trade.

I also agree with John that there probably are lots of things going on that are not easily explainable with science. That’s kind of a tough pill to swallow because people will continue to use soil as one of the key explainers why certain wines are the way that they are.

To me, the bottom line is that we don’t have all the answers. And people should not claim something unless they truly have a deep understanding of it. Is John points out, a vigneron or winemaker attends a piece of land for decades will have a pretty good understanding of the Ebbs and flows of that lands. He or she may not be able to, with certainty, explain in scientific terms what’s happening. But that doesn’t mean they don’t understand it and can’t explain it in a way that makes sense to them.

A somm or wine rep doing the same? Hmmmm.

Cheers.

Exactly Larry!

Good article and if you look back on some of the threads, some of us have been saying much of that for a long time. The next chapter in his article should be a bit about botany, which he touched on. The mere fact that something is present in the soil does not mean it will be taken up by, or even available to the vine. The roots of plants are pretty sophisticated and don’t just act like vacuums, taking up everything they encounter. There’s always a chemical exchange of ions, as he mentioned, and plants don’t need loads of something just because it’s around.

Moreover, because the humus and nutrients are in the topmost layers of the soil, the bulk of the root mass for any plant is in the top layer. If you’ve ever seen a tree that was toppled by a storm, it’s astonishing how relatively shallow much of the root mass is. So while older vines do have larger root systems, there’s no point to shooting roots far down where there are few nutrients. It’s pretty well established that the majority of root systems are in the top three feet of soil. And that’s where the mycorrhizae live. They have a mutually beneficial relationship with the roots and are responsible for much of the nutrition taken up by the vine.

Finally, the pH of the soil influences what will be available, as well as the form it is in. For example, iron can come as ferric iron, with a +3 charge, or ferrous iron, with a +2 charge. While the soil might be iron-rich, if it’s all ferric iron, that’s not doing much for your plants. So putting an iron pot next to your vine isn’t going to add any iron to the grape juice. If you have things like phosphorus and calcium, the pH of the soil will still determine whether those are going to be available to the plant. There are fairly well understood tables that show the availability of various compounds based on soil pH.

And then of course, there’s the overlay of BS. Once Alice opines on the subject, you know you’re no longer talking about anything with a factual basis.

Good read Alan.

Awwwww, Greg…mind your manners here!!! [snort.gif]
Tom

Having grown grapes in my own small vineyard for over a decade, I can say that I am truly amazed at how much difference a few feet can make wrt how a vine grows. I have vines spaced 3’ x 3’ and there are times when one vine can be showing signficant water stress and the one next to it isn’t showing any. Sometimes its easy to see the cause and effect, for example, I have a shading issue due to my neighbors’ trees and it is easily seen in the growth pattern of the vines that get less sun in the afternoon. But other times, it just isn’t obvious why things change and why so abrubtly. I tend to believe its has more to do with soil structure, pH, slope, sun, and wind than geology but I won’t rule anything out.

Yet growers are very fond of stressing how deep their vine roots go.

I very much like the article, but I am also a firm believer in terroir. My conclusion is not that soil doesn’t matter, but that it’s a tricky and indirect relationship, with water, winds, temperature, bugs and microbes, elevation, slope, exposure, etc., etc.

But just saying “we have chalky/schisty/granity/loamy/whatevery soil” is only part of the equation.

I was going to say, “This is what Greg has been saying/posting for years!”

You’re focusing on uptake through the roots, though. What about other things in the environment that can dramatically affect wine flavors, from botrytis to eucalyptus scents and ambient yeasts? (Is there any evidence that the garrique in the south of France really does impart its aromas?) It’s not hard to imagine that some of those factors would be tied to geology.

Just speculating.

Everyone in the trade should be forced to read that article. Of course, many of us already know that the whole idea of tasting some mineral in the wine because it’s in the ground is total BS, but it’s a bit frustrating for me how often I still hear that fallacy repeated by people who really should know better.

So true.

But of course terroir does matter. Pinot noir from Romanee Conti does not taste like that from La Tache or NSG or CdBeaune or the South of France or California or South Africa. Where does the difference come from if not terroirs.

You seem to be missing the point, which is that, whatever “terroir” consists of, it’s not the minerals in the soil.

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Interesting article…Alan’s summary above makes sense to me.

Another significant & underappreciated factor is the grape vine clonal/genetic diversity that some areas have. Pinot Noir in Burgundy, where PN originated, for example. Burgundy has a massive number of PN variants compared to the rest of the world. The rest of the world adopting/planting a relatively small number of clones, those deemed as ‘best’ or ‘complete’, has made this worse.

I’ve been doing some reading/studying of coffee, which has the same issues. Ethiopia, where coffee originated, and Yemen and Kenya, similarly benefit from a huge number of genetic variants of the coffee trees they grow.

Not that the rest of the world isn’t growing/making interesting wine & coffee…but genetic diversity, not the ‘best clone’ is the way to go.

I agree, Alan. Also agree it is an article well worth reading and thinking about. The title is “Busting Terroir Myths,” but the article focuses almost solely on geology (or soil). To me, terroir encompasses soil, yes, but weather (wind, temperature, etc.) which affects the vines just as much as the soil. Location (flat or hilly, etc.). As Greg said, I’d like to see a follow-on article that focuses on botany. I understand the intent of the article is to debunk the idea that the geology translates to the taste of the wine in the glass. I’m with him there. Hope he gives us more thoughts on the rest!

I attended a seminar at NASA Ames about 15-20 years ago as a guest of a good friend and wine lover working there. The speakers and attendees were NASA employees with strong interests in wine who basically laid out the premise the specific geologic composition of a vineyard’s soil is not being absorbed by the vines and transported to the grape and influencing flavor or aroma.

My reaction was similar to John’s and I immediately thought of the well studied and documented vineyards of Burgundy with visions of many dedicated monks. I weighed the detailed records from hundreds of years vs the brash 21st Century geeks saying the vines had no ability absorb a flavor from the predominant indigenous soil/rock. Stalemate; based on lack of more complete info which appears to be forthcoming.

I do agree that the microbes/bugs breaking down organic matter does matter and that the particular soil and microclimate around vines may provide specific conditions effecting the breakdown to absorbable influencers, as do certain additives/fertilizers(be they from a bag or an animal horn. Ha!)

Therefore, the decaying Eucalyptus leaves and seed/pods falling or blown onto Martha’s Vineyard’s specific soil in that microclimate could potentially provide the widely acknowledged mintiness assuming that responsible molecule does not get broken down itself and is absorbable. Or is it the pollen? The Eucalyptus behind my house started flowering just a few weeks ago , however, well after harvest. Mouton is know to have mint qualities too, but with no Eucalyptus, I bet. Damn.

We had a term in the hallowed corridors at college for this type speculation, “mental masturbation”, applicable specifically here in terms of no short term significance. But, it is fun to wonder and theorize what our consuming fascination with grape juice is actually based upon, huh?

The well-known eucalyptus note on Martha’s is no mystery (at least it seems to me). When you have eucalyptus groves nearby a vineyard, their oils are bound to land on the grapes, and go straight into the fermenter.

If you haven’t been there, a remarkable example is Australia’s Blue Mountains. This is a heavily eucalyptus forested area. When you look out over the valleys, you can literally see (and smell) the thick haze of oils in the air.

I guess you could call that Martha’s eucalypt note “terroir”, in that it’s something local and unique.

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Is anyone aware of any studies showing how much soil gets deposited on grape surfaces and stays there? I wonder how much character we recognize as terroir (chalk, minerality, non-brett earthiness) isn’t just resuspended soil. Microscopic particles get suspended in the air by wind, impact of rain drops, and any creatures or equipment crossing the ground nearby and some of that must be landing on grape surfaces. Some of those will make it into the juice during crushing and won’t necessarily settle out and some may be soluble. There are certainty particles originating from the soil are getting on the grapes but I don’t have a clue if that explains at least some of the terroir question.

I’ve been saying this for decades. “Terroir” is marketing, not science. People seldom agree with me, since their livelihoods/egos/gustatory constructs depend on the idea.