Understanding The Terroir of Burgundy part 4.4: Erosion: a challenge to the authenticity of terroir

Erosion Vosne wider implications

Our best understanding of soils of the Côte de Nuits:

In trying to grasp the relationship of the wines made soil from particular crus, many writers, myself included, had come to fundamentally incorrect conclusions regarding terroir. My version, could be summarized into this:

I believed that chemical and mechanical weathering of the limestone bedding naturally created soil types that were dictated by their position on the slope. Highest on the slope, the compact limestone soils were produced by the simultaneous production of clay and erosion clay. Lower on the slope, where transported clay enriched the otherwise arid, colluvial soils, I believed that if farmed carefully, clay production could remain in a relative of a state equilibrium with clay erosion. While, it most of these vineyards may not absolutely been in their natural state as when the Romans arrived, of many mid-slope Burgundy vineyards, I felt were relatively authentic in their terroir.  

A challenge to the authenticity of terroir:

Vosne-Romanée Les Damaudes, sitting upon the upper-most slope, with a 12% grade had equal parts clay and gravel in 2004. This is despite already having lost 54mm depth of clay sized particle since 1952. In the foreground, Vosne Malconsorts is allowed to grow it's grass in June of 2012. photo: googlemaps

Vosne-Romanée Les Damaudes, sitting upon the upper-most slope, with a 12% grade had equal parts clay and gravel in 2004. This is despite already having lost 54mm depth of clay-sized particle since 1952. In the foreground, Vosne Malconsorts is allowed to grow its grass in June of 2012. photo: googlemaps

The data of the 2008 paper by Quiquerez, Brenot, Garcia, Petit and Catena however, presented far wider implications than the study’s intended focus, being the impact of the erosion upon the soil. The study’s plot site, high up on the hillside, with a long, 12% grade, would challenge the perception that upper-slope Burgundian soils do not have high percentages of clay and silt. This vineyard, with its 40% clay content, at the onset of the study, is doubly surprising, given that the data showed these materials exhibit a high erosional rate out of the plot area. 

This study not only gives us a prophetic view of this vineyard’s future soil but also clearly illuminated a much more fertile soil in the past. Just as this vineyard once had an exceptionally high clay content, there is every reason to believe this was also true across the breadth of Burgundy vineyards, indicating a very different erosional story played out regarding the ‘arid’ soils of elite mid-slope vineyards. This information directly challenges the authenticity of the terroir vineyards as they exist in Burgundy today.

What the study of this vineyard tells us is that, at least on this site, there has been a relatively tight erosional timeline, with much of the damage occurring over the past half century. Additionally, the erosion is projected to finish its ‘third act’ in Les Damaudes, over the next 25 years, at which point it will have a classic Burgundian compact limestone soil.  While it would appear that mechanized farming as the most erosive in this vineyard’s largely unreported history, we know that there was massive erosion in other vineyards over the centuries. The remaining question is: What about the historical farming of this vineyard allowed its clay to remain in this parcel of Les Damaudes?

*This article is based on the findings a pair of studies chronicled in Part 4.3, and centers upon the upper hillside plot of Vosne-Romanée’s village cru of Les Damaudes.

Why is this study so important to our understanding of Burgundy?

It has slowly become apparent that the problem in talking about the terroir of Burgundy is this: We really don’t know what the wines of Burgundy might have naturally been, had men had both the knowledge and forethought to do what it would take to preserve these vineyards centuries ago. However, a study like this (click here) gives us the ability to hypothetically see both where this vineyard is going, and what it might have been like before man caused so much erosion upon the hillsides. We were lucky that the researchers chose this particular vineyard at the top of VosneRomanée for their study. Les Damaudes is a steep hillside vineyard (in the most revered of villages) that is only midway through its journey of erosional destruction.  A study of a vineyard from any of the other lesser appellations could easily be dismissed as not being applicable to les grands villages de Bourgogne. But with a vineyard within VosneRomanée, there is no doubt as to the applicability of the information, as this vineyard is in the immediate vicinity of some of the greatest vineyards in the world, including La Tache and Romanée-Conti.

soil projection

The projected future soil composition of Les Damaudes over the next 5 storms (roughly 25 years) Click to enlarge.

It has become increasingly clear through the research in preparing this series of articles, that vineyards like Ruchottes-Chambertin have been so seriously degraded by the techniques of the farming employed there, that the terroir we talk about today is one that wears immense repercussions of the farming practices of the past centuries. However, it seemed plausible, that the upper slopes could naturally have developed a compact limestone soil, (one that is 85 to 90% crushed limestone and only 10 to 15 % clay). But these studies re-orient our thinking, forcing us to realize that this is not a soil type that is natural to Burgundy. Because of that, it is not a terroir that is natural to Burgundy.

It is not to say that these vineyards, with their degraded soils, do not produce beautiful or interesting wines, but we must realize that this is a vineyard condition that has been inflicted by man. In the truest sense, Burgundy now has a terroir that has been drastically altered, metamorphosed by the actions of man.

Note: at the bottom of this article I discuss data gaps and the certain information the study might have provided which would have been key to a more complete understanding of the soil of Vosne Les Damaudes. 

2004: Establishing a soil base-line

Although the changes to the soil makeup after the 2004 storm were covered in-depth the latter half of Part 4.3, it is the basis for projecting what the soil make up was in 1952, so it bears a brief retelling now.

Click to enlarge. Adapted from the paper "Soil degradation caused by a high-intensity rainfall event : implications for medium-term soil sustainability in Burgundian vineyards" Quiquerez/Brenot/Garcia/Petit, Catena 73, 2008

Click to enlarge. Adapted from the paper “Soil degradation caused by a high-intensity rainfall event: implications for medium-term soil sustainability in Burgundian vineyards” Quiquerez/Brenot/Garcia/Petit, Catena 73, 2008

In June of 2004, a storm, which was unusually large for Burgundy, dropped 40 mm of water on Vosne Romanee over a 24 hour period. The effects of that storm were studied, and the researchers determined that the vineyard plot had irrevocably lost between 1.8 mm and 4 mm soil due to erosion, a vast majority of which were very fine particles under 63 μm in size.  The material lost was clay and silt since erosion most efficiently targets these tiny particles. (1)

To the right is a graphic I adapted from the study to show the grain size distribution of the soil after the 2004 storm. Each rectangle represents a range of particle size. I also included the before level of clay and silt sized particles to illustrate the loss of those materials, which was shown as 25% in a graph in the study.

 

1952: the soil content of the past

Given the study’s data, we can extrapolate, at least conceptually, what the clay content on these slopes the vineyard was planted in 1952.(2)  Starting with the fact 2004 the hillside contained roughly equal parts clay and gravel at 40+% each; the balance being sand, that we can add 54 mm more super-fine material (smaller than 63 μm) that it did in 2004.  If we assume that past soil loss rates were similar to that of the 2004 storm, we can postulate how much clay would have been present in 1952.  This figure would be much easier to arrive at if the researchers had given us the soil depth, which would allow us to estimate the volume of gravel (colluvium) and allow us a much more accurate estimate, but that information was not within the scope of the study.

Click to enlarge. Adapted from the paper "Soil degradation caused by a high-intensity rainfall event : implications for medium-term soil sustainability in Burgundian vineyards" Quiquerez/Brenot/Garcia/Petit, Catena 73, 2008

Click to enlarge. Adapted from the paper “Soil degradation caused by a high-intensity rainfall event: implications for medium-term soil sustainability in Burgundian vineyards” Quiquerez/Brenot/Garcia/Petit, Catena 73, 2008

The soil loss projections of the next five large storms, predicts that erosion will remove up to 20 mm in-depth in places. The lost material, it is expected would continue to consist of primarily be smaller than 63 μm in size. 

However, would it not be logical assume soil losses of previous storms were similar to that of the 2004 storm? If so, it would not be unreasonable to apply the projected soil loss, in order to estimate the vineyards clay percentage in the past.  If these big storms (of 40+mm rainfall per event) happen every 5 or so years, we can estimate that thirty years ago this same hillside may have had as much as a 70% clay content. How much clay existed before the plot was planted in 1952 can not readily be determined without establishing a rough estimate of the volume of gravel in the vineyard, but it is likely that the vineyard, may have had clay content 85%.  Such a high percentage suggests that either this plot was either not farmed before it was planted in 1952, or was farmed quite differently in the past than it is now. 

In Retrospect

We should not have been surprised that the soils of Burgundy are not as nature created them. We should have suspected something was amiss long ago because the soil type in Burgundy today is one of an arid climate. France, and the surrounding Burgundian countryside, however, do not have an arid climate at all. Rather the climate is classified as semi-continental, where rain is frequent and happens virtually year around. These soils would naturally have at least some petrogenetic development, which it is doubtful that any vineyard in the Côte d’Or does. We were told and simply wanted to believe that the wines of Burgundy are naturally and uniquely sparse of nutrients and clay. Additionally, we have not wanted to believe that, in the course of making these great wines, man has precipitously hastened the decline of the greatest vineyards of the world, though poor farming decisions that have been made throughout the centuries. This has never been truer since the organization of vineyards for the mechanization of farming.


 

Gaps in the data: deficiencies in quantification

As transformative as this study is to our understanding of the wines of Burgundy, the paper, unfortunately, omits some fairly important information. First and foremost, it is unclear how the samples for the data were collected, and secondly how well the data actually represents the soil of the slope in the root zone. The report does say that the soil of the vineyard was homogeneous in its makeup, and no petrogenetic development was observed; meaning the entire vineyard was the same, with no observable generation of new soil. This indicates that what little organic deterioration may develop was washed away by erosion, and no soil horizons (layering) could develop  Lack of soil development and soil horizons would be caused the dual soil disruptions created by regular tilling and erosion.

However, the problem lies in the word “homogeneous”. Even if at some point the soil was homogeneous from topsoil to bedrock, erosional changes to the soils would primarily affect only the material nearest to the surface, and then most acutely in the rill affected inter-rows. Now, even after one storm, the soil is no longer homogeneous in its makeup, because the soil at a certain (unknown) depth would contain more clay and silt sized particles than the topsoil. Now there would be two soil types.

Because of this, we must assume that the researchers collected a shallow soil collection for the sample in order to determine particle size.(3)  Quantifying the depth of this sample is critical, was this a  sample from the first 25mm (1 inch) or 50mm  (2 inches) or from deeper, say 200 mm (8 inches) of depth which is the deepest that most tilling reaches? Further, when the samples were collected: ie before or after anthropogenic resupply of the sediment was returned to the slope, and before or after the soil was tilled, are both important factors in understanding the distribution of soil.  Additionally, knowledge samples at various depths of the sample would be instructive as the effective depth of the erosional change. This is ever truer after workers had returned the sediment to the hillside, and tilled back into the soil.

Root development through soil

The root zone on a hillside vineyard is often restricted to no more than 300mm (12in) to 460mm (18in) represented by the brown strip in the graphic above.  Original graphic of unknown origin.

It would appear that the study only represents changes to the surface soil: those that would most be affected by erosion, and anthropogenic resupply of the sediment to the hillside. it is possible but less likely, that the soil sample may have been taken down to a 200mm depth (8in), which is the standard reach of a plow shear. But even if samples were taken from the 200mm depth, that is only 2/3s of the minimum depth required by a vine for its root zone.

Despite questions and any doubts these numerical omissions might create regarding the validity of the numbers and projections from the study, the value of this information far exceeds reaches far into the black hole of understanding that existed before. For this reason, I accept these numbers and build in a fairly wide mental fudge-factor when considering the above.

 

 

Puligny Folatieres after a rain

A tractor moves on the road between Paul Pernot’s “Clos des Folatières” and Les Clavillons in Puligny-Montrachet photo source: googlemaps

 

Musigny anthopogenic resupply

“Anthropogenic resupply” of redepositing the sediment back upslope is now done with heavy machinery at Comte de Vogüé. photo: Steen Öhman

Musigny anthopogenic resupply 2

Heavy machinery at Comte de Vogüé. Given a major cause of erosion is compression, it’s hard to imagine this is really helping the situation much. photo: Steen Öhman

*Special thanks to Steen Ohman, sleuth, and vineyard historian who writes the excellent winehog.org, for providing me with the 1827 cadastre Map show above.

 


(1) The variance between the 1.8mm figure and the 4mm figure was not explained, but it is likely that lower sections of the vineyard, which were subject to a higher volume of rainwater runoff, and had developed rill erosion, were subject to greater levels of erosional loss.

(2) While the study lumps both clay and silt into a grouping of material by size under 63 μm, according to Wikipedia, as well as other sources, say that silt is primarily made up of the parent materials feldspar or quartz. Feldspar is prone to chemical erosion, just as is limestone, both of which metamorphose into clay (phyllosilicate minerals + water and air), while quartz will not erode due the same contact with the carbonic acid in rainwater.  Although granite (the major source of quartz-silt) is common in the areas surrounding the Cote, like in Beaujolais, it is not found near the surface in the immediate area. Although silt has been washed onto the Cotes by alluvial action and transported to the soils of the Cote by wind erosion, I have to assume that silt-sized quartz fragments are a very small minority in the area’s soil makeup. For that reason, I often refer to the study’s grouping of material under 63 μm, simply as clay. Clay, of course, is actually smaller than silt. Although the size definition varies between disciplines 1–5 μm, the metamorphological change that occurs upon clay is the ultimately defines clay, not its size.  * an underlying reason that I identify this material may also be that — no wine writer has ever attributed any of Burgundy’s success to silt. Am I cowering in conformity?

 

(3) How else could one explain a 15% change in a clay content?  The planting bed must be at least 30cm  (12 inches) for vines to be viable. Most vineyards have this with a much lower clay content, often to 30% less. If we were to use 30cm depth as a baseline, it stands to reason that the depth is likely 30% more than 30cm, being at a minimum 40cm of soil over the base rock though there is likely more. So, if the soil is 400mm deep, and 240mm of that are clay minerals, a 4mm decrease in the clay represents only a 1.7% decrease in clay content in the soil.

 

 

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2 thoughts on “Understanding The Terroir of Burgundy part 4.4: Erosion: a challenge to the authenticity of terroir

  1. Once again Dean, a well-researched and reasoned article. But perhaps you open a can of worms? One would almost have to look at the history of each climat to figure out whether an original terroir had been compromised by erosion. When you add that to the fact that many vignerons DO practice catching their eroded soils and returning the soil anthropogenically to the vineyard then the complexity and erosive effects become even less predictable. I think, however, that one can say with “generality” that the upper vineyards are stonier with higher limestone composition, and that the lower sites have more depth of clay and soil. And intuitively, the upper sites produce wines that are more linear, focused, precise, and “mineral” in expression, while the lower slopes express richer, fatter, deeper, but perhaps simpler, wines. The mid-slope tends to be where the Grands Crus reside, having, as it were, the best of both types of soils. This is all made even more complex by water retention, exposure to the sun, underground water sources, etc. I also believe that 200mm to 1 meter is an insufficient depth to be taking soil samples. In some excavations, I have seen roots penetrate to a depth of 8 to 10 meters, even in very stony soil through fissures in the bedrock. All in all, an extremely complex subject, which is only understood not merely as the development of terroir through “geologic” time, but how that terroir is “constructed” by man’s labors and desires. The concept of terroir is indivisible from man’s work in a given place.

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    • Hi Jerome,
      Thanks for taking the time to comment! I knew this early on, but one of the biggest problem with my series is who has time to read it? It is so vast, and densely packed with information, that even the most dedicated reader is likely not able to make enough time to read it all, or will miss key points because they have to go to work, the phone rings, or their mind wanders. In the course of these articles, I have dissected as many of these “worms” as I could locate, in that “can of worms”. I have truly tried to leave, as much as possible, “no stone unturned”. Links are at the bottom of the page if you have time for them.

      You take two excellent, and very interesting positions, both of which are at the crux of Terroir, and these articles.

      The first position questions the the basis of this particular article, in which I have changed tack from discussing purely Facts to looking at Clues. I liken this clue based exploration to how a physical anthropologist (something you know far more about than me) might work. Upon finding a few bones and tools, the author attempts to interpret. I may not give a full picture, but it is a place to start. Your point that you have to take the history of each cru, and the soils of each cru individually is in many ways valid. However, given time limitations of the writer, (and readership) coupled with the difficulties involved in assimilating a vast and increasing data pool, in order to arrive at something meaningful, does not seem possible. And That says nothing of the lack of historical record of each cru and how it was farmed. Because of this, I don’t think the method you are prescribing is possible. I believe, what I have done, is the next best thing.

      I do believe, however, this vineyard is a key to understanding how developed the soils of Burgundy actually had been, before man eroded them. Further, I believe that if today’s vigneron’s had access to making wine from their same vineyards, which had not been so substantially eroded, the wines that they could produce (with the right level of skill) would a be far richer, and more powerful. The premier crus would be grand, and the grand crus would be grander. An example of this that I used in the article was Cros Parantoux.

      The second point you make is that “terroir is indivisible of man”. I like this idea very much. This indeed is the entire basis of the concept of the Terroir of wine.
      And regardless of how the soil changes, whatever the cause, that is the terroir. But to embrace this “it is what it is” concept, is to accept it is ok to corrupt these priceless vineyards due to their continuing ignorance or expediency.

      Here is an analogy I was thinking about this morning:
      Imagine these vineyards are like car: the only car that you are allowed to own for your entire life. This is the only car you will to use to do your work. At first the car is perfect. But as you use it, it becomes more and more worn. You maintain this car, but you don’t spend all the time or money that you should to keep it in tip-top condition. Because you are in hurry to get to work, you get into a few “scrapes” now an again. Even though you maintain it, and pound out the fender, and bolt back on the bumper, it’s no longer the same car you started with. The frame is out of alignment, and it pulls to one side as you try to steer it down the road. Maybe it has caught fire. But this is your only car, and this is the one you need to use to get to do your work. This, in my mind, is what these vineyards are like: They are still indivisible to the man that farms them, and they still get the job done, but they are a fraction of what they once were.

      What do you think?

      Warm Regards,
      Dean

      Here are the links:
      The roots in “The Upper-slopes”
      https://diaryofawinebuyer.wordpress.com/2015/04/25/understanding-the-terroir-of-burgundy-part-3-3-the-upper-slopes/
      and the resupply of the soil in the second havlf of the voluminous Part 4.3
      https://diaryofawinebuyer.wordpress.com/2015/08/28/understanding-the-terroir-of-burgundy-part-4-3-erosion-and-rills-studies-in-vosne-romanee-and-monthelie/

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