Why Does Soil (Or Terroir) Matter So Much to Fine Wine?
Terroir is a term that the French invented and like to claim as their own. Terroir is the interplay of climate, terrain, soil, and geology, which gives a wine its unique taste. Together with the cellar development, terroir is an important factor in viticulture, as it significantly shapes the character of the wine.
But what exactly is terroir, and how far can this uniqueness be tasted in wine? The extent to which vineyard soil characteristics affect wine quality remains unanswered, and it is one of the most contentious issues in the wine world.
The Importance of Soils
In Europe, it is widely accepted that the characteristics of vineyard soils, along with the influence of climate, are the most important factors influencing the quality of grapes and wine produced from them. The most important soil characteristics are generally thought to be those that are particularly important for the vine’s water supply.
Particularly good wines are frequently produced on soils that are highly permeable to water on the one hand but also constantly supply water to the vines on the other.
However, the water supply should not be so abundant that the vines grow excessively vegetatively. It is also necessary that the soil not be overly fertile or rich in mineral nutrients. In this case, the plant produces only small leaves, allowing the sun to illuminate the entire foliage as well as the grapes.
In this case, the elaborate foliage clearing measures implemented during the summer are also scaled back. A sparing water supply also inhibits the growth of individual grapes in a beneficial way, because wine of higher quality can usually be produced from smaller berries.
The Influence of Soil Properties
The influence of soil properties on wine quality is not limited to the function of water supply, but also extends to other factors. The color of the soil is an important issue in viticulture. A bright floor reflects a great deal of sunlight while remaining relatively cool. Darker soils, on the other hand, absorb sunlight and convert it primarily into thermal energy; the darker the soil, the greater the energy yield. At night, the dark soils radiate energy like a heater, warming both the vines and the grapes.
Not only is the color of the soil important for its heat storage capacity, but so are its geological composition and moisture content. Because stone is much better at heat storage than sandy or simple soil, stony or stone-containing soils have a good ability to store heat and slowly release it again. Furthermore, Stoney soil is typically nutrient-poor and has excellent drainage.
Stone soils can hold little water, which encourages the plant to grow more roots, which gives it more stability – the grapevine can drive its roots up to 15 meters into the soil. The ability to store heat is enhanced if there is moist soil beneath a stony layer. The rock absorbs heat quickly and conducts it deeper into the earth.
The Ideal Soils to Produce Fine Wines
The water in moist soil can store a lot of heat and release it slowly over time, protecting the soil from evaporation and the associated stronger cooling by the protective rock layer. These soils are frequently ideal to produce fine wines.
Simply moist soils, on the other hand, cool quickly and then warm up slowly, resulting in very slow heat absorption on the surface. On such soils, the vines frequently get wet and cold feet, which usually results in grape ripening problems.
Some of the most famous vineyard soils are densely interlaced with stones, as in the Spanish Ribera del Duero, or covered with stones, as in several sections on the southern Rhône, or even consist of pure gravel, as in the Medoc, Graves, Pomerol, and St. Emilion.
The variables regulating vineyard soils’ influence on vines and grape ripening only work optimally in soils with a normal, healthy chemical composition. A soil that is excessively acidic or too alkaline, as well as an excess or lack of specific chemical compounds such as nitrogen, potassium, trace elements, and organic chemicals, can all have a negative impact on vine development, grape ripening, winemaking, and wine quality.
The interaction of these factors results in a wine’s independent personality and thus its character, which sets it apart from other wines. The more a grape variety is adapted to the soil and climatic conditions, the more clearly the typical character of a wine can be tasted. Although terroir does not only refer to the soil, of all the influences, the influence of the soil is the easiest to taste in the wine aromas – because the soil type influences the aroma of a wine in a very refined way.