So it stands to reason that if half of a vine is underground, that ground will probably have some sort of influence on the wine: does it not? It especially makes sense when you consider how much one vineyard site can vary from the next. I personally work at a winery where we make a series of wines from specific vineyards, often right next to each other and they often have a flavor that is totally different from one another. So what gives? You can’t blame the climate, the vineyards are one hill away from each other. It has to be the soil, right?
Well, maybe it is. But for what it’s worth, they’re not teaching us that’s the reason at winemaking school nowadays. This mystical power of soils that I had heard that wine “experts” talk about is exactly what I expected to learn about when I began a class called “Soils 101”. I walked in with open eyes, waiting for the professor to start telling me about how clay will give you more cherry in Pinot Noir and limestone gives you more minerality in whites. But alas, my dreams did not come true.
Instead, they taught us about the make-up of soil, the build-up of soils and the polar charges of the soil particles. I’m sure this is where your mouse is starting to slowly rove towards the “minimize” button in the corner, but stop it! Don’t let it get away! Everything I learned in that class boiled down to one simple fact about soil as it pertains to wine. One fact that defines how soil impacts the eventual fruit the vine produces.
(I’m gunna let this build up a little bit more)
Soil is a water and nutrient reservoir for the vines. As a vineyard manager, it’s your job to make sure you react to the soil, so you don’t get too much or two little of water or any nutrient so the vine grows ok. Each nutrient is like a box that needs to be checked so that your vines grow correctly. Magnesium? Check. Phosphorous? Check. And so on. I don’t know about you, but I found this to be one of the most disappointing lessons the Enology (winemaking) program had to offer. It pretty much smashed all my preconceptions of wine being an expression of the soil with a steel hammer.
So there you have it. In enology school, it is not taught that soil affects flavor. Of course, when I thought about it, I couldn’t help but deconstruct that argument a little bit. If it were true that soil’s primary involvement in the vine’s growth and the fruit’s development was as a pantry where the vine could go and source sustenance when it needed it, it would stand to reason that climate, canopy management, fruit load and clonal material would be the only factors to determine wine quality. However, a fact that most wine professionals accept as a given is that within every vineyard there is fruit of varying qualities.
So soil has to do something. What does it do exactly, though? One of my professors, Dr. Jim Kennedy did a study on this. He took a look at a vineyard in Oregon and picked two blocks (sections) that produced very different quality fruit. Then he took a look at the soil underneath. What did he find? The soil in the higher quality block retained less water.
So is water the smoking gun of soil science? I’m starting to think so. Dr. Kennedy’s work wasn’t the only piece of evidence I’d seen, I had read in a different wine textbook a similar finding by a researcher in France. It makes sense. If the soil retains less water than you get less growth in the vine, and as a general rule, that tends to develop better concentration in the fruit. In one of our viticulture classes we were shown a process called RDI- Regulated Deficit Irrigation, in which the vineyard manager carefully restricts the amount of the water the vineyard gets to increase fruit quality, and it seems to have been working for a long time. Do soils with low water availability have the ability to do this naturally? So it seems.
But before we mark this case closed, I have one observation. In soils and viticulture class, we talked about all the different nutrients the vine requires in the wine-making process: Iron, Nitrogen, Potassium, Phosphorous, Calcium, Magnesium, Zinc… …the list is almost as long as the list of nutrients our human body needs. Like the human body, the vine’s soil cannot be deficient in any of these, nor can it be taken in toxic levels. However, in the case of the vine, wouldn’t it stand to reason that a vineyard with a slightly higher iron content in the soil have a slightly different flavor than a similar vineyard with a lower iron content?
It’s an idea. I hope it’s a good one.