“Voodoo Magic” in Wine?
(Unrelated Copyrighted Trademark used to illustrate the idea)
Winemaking can be complex chemistry, artistic expression, or a mixture of the two, depending on the winery. That first “science-based” option is certainly the most accessible and also the reason so many winemakers have chemistry degrees. This approach (topic of the first piece in this series) utilizes empirical processes that have a direct, identifiable impact on the wine. Climate (topic of the previous piece in this series) is another easy to recognize factor when tasting wine (with training), but these last two pieces in the series are about the “voodoo” in the wine: soil type and vineyard management. I doubt many consumers would recognize the importance of this topic and most high-production bulk wineries rarely care, but for an estate winery under 50,000 cases of production… it is the key to differentiating an individual wine label . That is why you see so much maneuvering in the U.S. to establish new AVA’s (American Viticultural Areas). Winery owners are trying to attach special significance to the fruit source (vineyard location). Developing a unique wine profile is critical to marketing strategies for these producers. As a consumer, I am usually only interested in the “voodoo”, if I have visited that vineyard at the estate. Analysis of soil and vineyard management is just too dry a topic to review without some sort of personal connection. Does the appellation factor into your choice in wine? Do you look for “Rutherford”, or “Margaux” on the label, before you select your Cabernet Sauvignon/blend?
I am reasonably sure no one is interested in a chemistry primer on soil composition, so I will try to move this discussion towards general soil categories. These vineyard site characteristics can have recognizable effects on quality and flavor. Let’s bypass mineral composition and move directly to key factors affecting the vines. There are many different vineyard soil types: Silt, Sand, Loam, Clay, Gravel, etc. There are even more specific sub-types: Calcareous, Schist, Shale, etc. Although, these soils all have just a few tangible characteristics that have well-known effects on the vines.
Water Drainage and Free Organic Matter – Soils that do not drain well, or are too fertile produce horrible wine. When vines grow vigorously, the berries are larger, the juice after press is less concentrated and the resulting wine is one dimensional. Examples: Poor Soil – Loam, Silt. Better Soil – Gravel, Sand.
Soil pH – Basic soil (higher pH) is the key here – think regions like Champagne, Loire, West Paso Robles and other locations with calcareous soils high in calcium carbonate. All the anecdotal evidence for this shows basic soils produce acidic wine – a key component to the structure of quality wine. I won’t bore you with the theoretical chemistry, but evidence seems to confirm this idea. Better Soils – Calcareous, Chalk, Marl.
Soil Depth – An impermeable layer should not be less than 40″ below the surface for dry-farming of the vines (dry-farming should be the goal).
Water Retention – This may sound contradictory, but the best vineyard sites have both good drainage at the site AND good water retention in the soil. These characteristics exist and are excellent for dry-farming vineyards (no irrigation).
Varietal Soil Preferences
Interestingly, when specific varietals are grown in an area over long periods of time (decades+) successfully, the vines seem to adapt to the terroir. This optimization has never been formally studied, but general observations abound in the world wine community supporting this idea. Currently, vineyard root stock for each varietal is available in many slightly different clone options adapted to different climatic and soil conditions. The growers choice of which clone to plant can be a make, or break business decision. Areas like Burgundy, where Pinot Noir has been grown for more than 500 years, have allowed the vines to adapt naturally and you can tell the difference in quality.
Grape varietals often have their own soil preferences:
- Cabernet Sauvignon produces the best wine when grown in Gravel and Volcanic soils.
- Merlot produces the best wine when grown in Sandy Clay.
- Chardonnay and Pinot Noir produces the best wine when grown in Chalky soils.
Some varietals seem to do well in many different soil types, but manifest radically different flavors:
- Sauvignon Blanc has tropical fruit flavors when produced in Marlborough (New Zealand) and lemon and/or grapefruit flavors when produced in Napa Valley (California).
- Zinfandel tends toward Strawberry flavors when from Dry Creek (Sonoma County), but can have strong jammy blackberry and blueberry notes when produced in West Paso Robles (Central California Coast).
Estate Wineries Embracing Vineyard Variation
A few years ago the head winemaker Dan Petroski at Larkmead Vineyards offered the best explanation I have heard for optimization of variable growing conditions at a single vineyard site. In recent years, Larkmead has invested heavily in their belief that soils and micro-terroir make a difference in the quality of the wine. Their estate vineyards (108 acres planted) have been separated into 40+ separate vineyard blocks, some quite small (against typical industry thinking). Some of these vineyard sections were re-planted to change row direction and take advantage of improved sun orientation and drainage characteristics. The blocks were separated based on soil testing and observation to define clearly different growing conditions. Where this gets really interesting is their further investment in numerous smaller stainless steel fermentation tanks. For those who say terroir impact on wine is a fallacy, they need to taste the lot to lot differences side-by-side at an estate winery using this vineyard strategy. This system of wine production allows the winemaker to take advantage of distinctly different wines and offer them as separately bottled vineyard designate releases, or blend the individual blocks to achieve a better, more complex product.
My Previous Recommendations
Now, let’s put this information to use (remember the “voodoo”). In past pieces, I have suggested that certain growing regions tend to generally produce better quality over-all. Let’s explore a few reasons why…
Valley Floors (in the flood plain) – These locations tend to have a high percentage of silt, but not always. For example, the right bank of the Garonne River in Bordeaux has sandy clay soil (premier Merlot region in the world). Putting aside complex locations like Bordeaux and speaking in generalities, valley floor locations produce simpler wines that often are missing structure… especially when grown in warm climates, examples: Puglia, Italy or Inland Valleys, California. There are some interesting exceptions though. Certain varietals (like Tempranillo) can grow in these locations (i.e. Ribero del Duero) and thrive, but I would be careful if you are searching out quality. Know your varietals and their optimal growing regions, unless you are comfortable experimenting with hit, or miss results.
Mountain/Hill Sides – These locations tend to be virtually barren, with well-drained schist, slate, granitic (etc.) topsoils. In many cases, wine grapes are the only crop these soils can support. Again, this seems contradictory, but these regions can offer perfect conditions for many different wine grape varietals. Examples of Mountain/Hill type optimal growing regions: Syrah – Northern Rhone, Nebbiolo – Barolo, Riesling – Mosel, Cabernet Sauvignon – Spring Mountain.
Examples of a few optimal growing regions by varietal: Cabernet Sauvignon – Napa Valley, Left Bank Bordeaux; Merlot – Right Bank Bordeaux, Spring Mountain; Pinot Noir – Burgundy, Willamette Valley; Syrah – Rhone Valley, Barossa Valley; Malbec – Mendoza, Riesling – Mosel, Chenin Blanc – Loire Valley, Swartland, Stellenbosch.
No one really knows for sure what specific chemical composition is changed due to these soil factors. Neither is it known the process by which these soils change the character of the wine, but I can tell you, a trained palate can taste wine blind and describe the type of terroir it originates from.
Is this topic never-ending? Yes! The potential for exploring variability in wine character is quite literally endless. Although, I will endeavor to finish this series in my next piece with an evaluation of Vineyard Management and its impact on wine.
3 responses to “Why Do Wines Taste Different? – Part 2c: Soil Types”
i have thoroughly enjoyed reading your article and find it very meaningful in the subject of wine appreciation. I am from Trinidad on the West Indies. I have worked in the Marketing ,Distribution, and general promotion of wine for the last 30 years. I am now importing wine in bulk and bottling here.
Thanks Mairin! I am glad you have enjoyed the series. My intent was to take technical wine topics and both make them more easily understood and use real-world examples of their impact. I look forward to having fun with future topics!
Many thanks for taking the time to write those wonderful articles! It was like revising for the Diploma again! Your articles are very concise and help greatly in class preparation! Please keep them coming on other topics.