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Why is soil important for wine? A complete guide

It seems that the different types of soil for growing vines are just an obsession of sommeliers and insiders. Instead, it is a key component of terroir. But does the subject really not make its way into the hearts of wine lovers? We try, with a simple and comprehensive guide.

How do we tell the story of the fascination of different soils, which play a leading role and determine the qualities of the wine we find in our glass?

1. Let's start here: how does the vine behave?

The vine is very demanding with the climate, but has an extraordinary adaptability to different types of soil. That said, it also has its preferences for soil.

2. What are the least suitable soils for growing vines?

The vine does not like fertile soils, which give wines that are not very fine and poorly suited to ageing.

It also gives less good results in soft, moist and salty soils (and here we get high school memories of Ulysses trying to make himself look crazy by throwing salt on the field).

3. What are the best soils for growing vines?

Poor, well-drained soils are the best for wine. The concept is: less water, more concentration of flavours in the grape and in the glass. An example? Soils called 'Grave', which are pebbly and thus result in poor water for the vine, allow the grapes to grow less and thus concentrate sugars and flavours.

Moreover, the hilly areas are excellent for quality viticulture. For various reasons, here we are interested in the excellent drainage due to the sloping soil.

4.Does the same vine variety give different results in different soils?

Yes, in different soils the same grape variety gives different wines. Just think of Nebbiolo, to which we have dedicated a selection designed by sommelier Nicola Bonera. We discovered the Nebbiolo of the Langhe, while other wines originate from the same grape in the Vercelli area (Gattinara and Bramaterra), in the Biella area (Lessona), in the Novara area (Fara, Sizzano, Ghemme), in the Turin area (Carema), in Valle d'Aosta (Donnaz and Arnad-Monjovet), up to Valtellina Superiore with its heroic vineyards.

5. Do different grapes have soil preferences?

Some grape varieties adapt very well to different soils, but most give their best in certain specific conditions. Here are some examples:

Albana prefers hilly, clayey soils of medium to low fertility..

Aleatico likes hilly, loose soils.

Arneis prefers light (sandy) soils.

Barbera does well in clayey, medium to low fertility soils.

Cabernet franc loves hilly clayey, pebbly soils.

Cabernet sauvignon prefers clayey soils that are not very fertile.

Corvina prefers alluvial soils.

Carmenère likes loose, low clay, pebbly soils.

Durella loves lime-clay soils, on hillsides.

Erbaluce grows in clayey sand and pebbly soils.

Freisa prefers calcareous soils.

Garganega prefers fertile, loose soil.

Grechetto di Orvieto prefers hilly, medium-fertile, clayey soils.

Gewürztraminer expresses itself best in basaltic soils.

Grignolino is at its best in dry, sandy soils with a fine texture, at an altitude of no less than 300 metres.

Groppello likes loose soils, on hillsides no higher than 300 metres, well exposed.

Marsanne prefers soils that are not too rich and humid.

Malvasia nera prefers medium-textured, even fertile soils that are not excessively calcareous.

Malvasia di Sardegna grows well in calcareous-siliceous soils.

The Monica vine grows well in calcareous-siliceous or calcareous-clayey soils, which are not humid and fertile.

Montepulciano loves medium-textured, deep, well-exposed soils.

Moscato bianco prefers calcareous marl soil.

Moscato di Scanzo likes lean, skeleton-rich soils.

Müller Thurgau prefers hilly, not too dry, fertile, non-calcareous soils.

Negroamaro prefers chalky-clayey soils.

Pinot blanc prefers soils with a low amount of active limestone.

Pinot noir prefers low fertility, calcareous or clayey-calcareous soils.

Raboso del Piave prefers alluvial or stony-alluvial soils.

Raboso veronese prefers pebbly, alluvial, sandy-silty soils in the plains.

Ribolla gialla prefers hilly, scarcely fertile areas.

Riesling loves slate (a hard, dark rock that captures heat).

Sylvaner verde loves acid, light, pebbly soils.

Teroldego loves very draining soils.

Torbato prefers siliceous-clayey soils.

Trebbiano di Abruzzo prefers hilly, clayey soils.

Trebbiano Romagnolo prefers cool, fertile soils with limited summer drought.

The preferred soils of aromatic Traminer are those with good water and mineral supply.

Verdicchio expresses itself well in calcareous-clayey soils.

Verduzzo friulano prefers well-exposed, poorly fertile hilly soils.

Vernaccia di Oristano prefers alluvial soils of good fertility.

It is also for this reason that the disciplinari (i.e. the rules that define how DOC and DOCG wines should be made) specify the nature of the soils required to make the wine fall within the denomination. Some examples:

For Asti and Moscato d'Asti the soil must be calcareous or limestone-clayey.

For Barolo and Barbaresco, the soil must be clayey-calcareous.

Chianti requires arenaceous, calcareous-marly, schist-clayey and sandy substrates.

Franciacorta requires loose, pebbly and graveled soils.

Valtellina Superiore requires a sloping, stony soil.

6. Other facts about soils

Sandy soils are not attacked by phylloxera, nor are tufaceous soils of volcanic origin.

The type of soil intersects with the exposure of the vines: the most suitable exposure is that which allows good sunshine and luminosity (south or south-west).

But to go deeper into the various soils, there are 3 key aspects: chemistry, physics and geological history. High school memories again...

1️⃣CHEMISTRY

What is the most common component in vineyard soils?

Limestone (calcium carbonate) is in practically all soils. It is followed by marls, schists and clays.

How does soil type influence wine?

- A calcareous-marly soil tends to offer grapes with intense aromas, good structure, rich alcohol and sugar content, and low acidity.

- A calcareous-clayey soil is more prone to growing black grapes, gives wines with intense colour, rich body, complexity, acidity and longevity. They give wines of great quality and are most common in Italy.

- A calcareous-sandy soil gives delicate, light wines with fine aromas, good acidity, pleasant but not always suited to ageing (we have dedicated a selection to this, created by sommelier Luisito Perrazzo).

- Marly-ferruginous soils, i.e. red soils, are also excellent.

- Acidic soils (low pH) yield sapid wines with good freshness, but not great structure. As for basic soils (high pH, above 7), they are the majority.

2️⃣PHYSICS

What is soil texture?

It is another important factor, this time physical, indicating the grain size of the soil particles..

From the largest to the smallest, we have sand, silt, clay (which together form the 'fine soil'), along with particles larger than 2 millimetres in diameter, together called skeleton.

How does soil texture influence viticulture?

- The absolute predominance of coarser particles (sand) can make the soil too loose and thus not allow the vine to retain minerals. But if the percentages are balanced, the other particles are arranged around the sand.

- The prevalence of smaller particles (clay) favours soil compactness and absorbs water, making drainage difficult. Here, too, it depends on the percentages: if the clay is not too abundant, it retains nutrients but does not prevent oxygenation of the roots.

- Silt has intermediate characteristics between sand and clay.

Pebbles and stones do not have agronomic functions, but make the soil permeable and the life of the winegrower difficult by preventing the use of mechanical means..

What is the best soil texture for growing vines?

Soils generally do not have one texture, but different percentages of sand, silt and clay particles. Ideally, the best soils are those of 'medium texture'.

3️⃣STORY

Does the different origin of the soil, in terms of geological history, influence the wine?

Of course it does. Wines that grow on soils that have a particular geological history give different aromatic nuances in the glass.

What are the main soils then?

The fluvial, alluvial, sedimentary, glacial soils. And the legendary soils of volcanic origin, which give the wine unique nuances.