If you have ever noticed the difference in taste between the same grape from different parts of the world - congratulations, you’ve brushed up against one of the most grounded mysteries in viticulture: the soil and the terroir.
To understand wine, you have to understand that a grapevine is essentially a biological diary. Every glass of wine tells the story of where the plant lived; what the weather was like, the soil, the hands that made it and the life of microbes and yeasts that it holds.
In the world of wine, we talk about terroir with a reverence usually reserved for favourite artists, and while the terroir is the unity of climate, topography, micro-life and sunlight, the dirt beneath our feet is the literal foundation of everything we taste.
If you have plants at home that you take care of with love you already understand the importance of different soils and what part they play in the wellbeing of our green companions, but how does this reflect in the bottle?
First of all, we need to understand that just like our houseplants, a vine’s health depends on how its roots interact with water and temperature, but in viticulture we want the vine to “struggle” more than a common fern. That’s because if you put a vine in a rich, fertile soil with easy access to water, it gets lazy. It grows plenty of green leaves but produces watery, flavourless grapes. When the soil is poor, the roots have to dive deep into the earth to find moisture. This struggle forces vines to focus its energy on the grapes resulting in smaller berries with much more concentrated flavour and complexity.
The soil imprints the flavour through chemistry and physics, not by feeding the grape rock juice. It’s about how the dirt makes the vine behave.
But let’s get deeper into some of the soil compositions and their personalities to try and understand better how each soil interacts chemically with the vines.
1- Limestone and Chalk
Formed from ancient, crushed seashells, this soil is the holy grail for some grapes, like Chardonnay ,and can be found in regions such as Burgundy, Champagne, South England and parts of Rioja.
Before we get into the specifics of the soil, let’s clear up a classic wine misconception, the “Minerality Myth”. A grapevine is not a straw. It doesn’t suck up the flavour of wet stone and deposit it into the grape. Let’s just say that if you licked a piece of limestone it wouldn’t taste like a £100 bottle of Chablis.
These soils retain water for survival in dry periods and they are well-draining during heavy rainfall – the best of both worlds! This balance is vital for the acidity, structure and balance in the final wines. The high PH pushes the metabolism of the grapevine into a state of metabolic stress. It interferes with the roots’ ability to absorb some minerals, namely iron. To maintain its natural balance the vine concentrates more organic acids in the grapes. It’s not the minerality of the chalk that you can taste in the Chablis but the high acidity interacting with your mouth.
Try Domaine Alexandre Chablis Vieilles Vignes 2023
2- Clay
Clay soils are found in regions like Bordeaux and Barolo. Clay retains water and it’s rich in nutrients but very dense - resulting in the roots having to exercise a lot to get those nutrients and water out (imagine sucking a very thick milkshake out of a tiny straw). It also stays a lot cooler than other soil types which will slow down the ripening process of the grapes.
This results in wines that can maintain high levels of acidity while developing good structure and depth, pronounced tannins and concentrated fruit flavours.
If you drank our Barolo, you know what we’re talking about.
Try Cantine Povero Priore Barolo DOCG 2021
3- Gravel
If clay is the smothering parent that holds on too tight, gravel is the laid-back one that lets the child do whatever they want.
Gravel soils are common in coastal or river regions, such as the left bank of Bordeaux or Rhone. It provides excellent drainage, forcing the roots to grow very deep to find water. This stress on the vine often leads to lower yield by forcing the plant to put more focus onto less fruit which in turn, gives the grapes more concentrated flavours. Gravel soils also retain heat, which assists in ripening in cooler climates.
Try Domaine Loyane Lirac Rouhe Cuvee Elie 2020
4- Slate
After mentioning the heat retention of the gravel, we must talk a bit about slate. If you’ve been in our Plymouth shop you’ve seen it already hanging on the neck of our bottles to display the price. But in regions like Mosel in Germany slate is fundamental for the vines to grow through the cool climate. Absorbing the heat during the sun and gently radiating it back overnight.
5- Volcanic Soil
These soils come from eruptions and are packed with minerals and sulphur. Regions like Etna in Sicily or Santorini in Greece, can produce wines with incredible power and character, usually defined by a salinity and smoky flavours.
Not long ago we mentioned that the roots don’t suck up flavours from the soil, so why can these wines have smoky flavours? The answer is in micro-life. The air full of sulphur around the volcano creates a micro-life unique to this environment. The yeasts and microbes that form around the grapes are different from the ones that would form around grapes who live in an environment without sulphur. And this micro-life is what creates those compounds that give those distinct smoky flavours.
The vine isn’t just growing from the volcano, it’s surviving it, and in turn, the volcano doesn’t give the grapes flavours, it gives the wine an attitude.
Try Masseria Setteporte Etna Bianco 2022
6- Sand
Sand is the opposite of clay, water runs through it like a sieve, it reflects sunlight like a mirror because of its light colour. Sand is also incapable of holding onto any nutrients. The vine here struggles quite a lot as if it’s undergoing starvation because it can’t find any nutrients to build body or tannin. This starvation and the presence of compounds that provide our grapes with delicate aromas, is why wines that grow in this soil appear softer and more elegant.
There’s so much more that can be said about so many different types of soil, but we know that you would rather be in front of our enomatic machines snacking on some delicious cheeses, so pop in and ask the team as many questions as you want about the soil and the rest of the fantastic world of wine - I’ll share a little secret, it’s our favourite part of the job.
The next time you sip a glass of wine, take a second to think about these green companions that grew the grapes and all the factors that helped them (or not) through the process. Behind every bottle there is a story that travels deep into the Earth beneath us.
The wine maker can choose how to make a wine shine, but the soil sets the limit of what is possible. By understanding the soil, we can truly start to understand the soul of the wine.
Written by Ettore Arena