“Terroir” is a French expression difficult to translate in many languages, but with an enormous impact on the quality and characteristics of the wine. Among the many definitions of terroir, the one we like the most, for its simplicity, is “terroir is an interactive ecosystem, in a given place, including climate, soil and the vine”.
There are therefore many variables differentiating a specific terroir and it is difficult to correlate all these variables to the wine aromas. But 4 of these variables have been studied and have an impact on the aromatic attributes of the wine: temperature, light, water status and nitrogen status.
Nitrogen is the only mineral coming from the soil which has been proved to impact the vine vigor, the berry size and its aromas. In fact, soil supplies vines with many other minerals, but there is little evidence that these soil minerals are major drivers of terroir expression and no demonstration is provided on how soil minerals could possibly be transformed into aroma compounds or other sensory attributes of wines.
Air Temperature and wine aromas.
Temperature affects the ripening time/window of the grapes. Ripening cannot be too soon in the year or the wine would lack balance and complexity and it cannot be too late or the wine would be too green. It is not always easy to disassociate the effect of temperature from light and water deficit. In general:
- high temperature seems to increase the aromas of caramel and dried fruit (also due to grape dehydration), truffle (e.g., aged Bordeaux), kerosene (e.g., Riesling), spices and tobacco (e.g., Bordeaux).
- cool temperature increases bell pepper, menthol (e.g., Cabernet Sauvignon) and green notes (e.g., Sauvignon Blanc), grapefruit (e.g., Sauvignon Blanc); black pepper (e.g., Syrah).
Grape light exposure and wine aromas.
- More light, in general, produces more fruity aromas. In particular, it increases the aromas of rose, grapefruit, passion fruit, black pepper, kerosene, dried fruit.
- Less light increases bell pepper and green notes and decreases the aromas mentioned above.
Water status and wine aromas.
Water status is impacted both by rain fall and the ability of the soil to retain the water.
- Higher levels of water increases the aromas of bell pepper, black pepper, kerosene.
- Lower levels of water, or water deficit, in general produces fruitier wines. In particular, a moderate water deficit can increase the aromas of flowers, passion fruit, citrus, truffle (in aged wines), caramel, dried fruit, kerosene.
Nitrogen status and wine aromas.
High nitrogen status in the soil increases the vigour of the growth of the vine. For this reason, it increases the bunch shading thus affecting negatively the temperature and light exposure of the grapes. When it was possible to disassociate the nitrogen status from temperature and light shading, the following correlations were found:
- Higher levels of nitrogen increase aromas of red fruit, grapefruit, tropical fruit, truffle (in aged red wines). Indirectly, high nitrogen status can increase bell pepper aromas and green notes as shading of the grapes increases.
- Lower levels of nitrogen in general increase flower aromas and kerosene and decrease the aromas above.
From this overview, it is clear that the ideal terroir depends on the grape variety and the type of wine that must be produced. For instance, high nitrogen may be good for a Sauvignon Blanc with green and grapefruit notes, but it may be bad for a Cabernet Sauvignon which could take on bell pepper notes that are too powerful.
Some the examples of famous terroir/grape variety combinations:
- Bordeaux and Cabernet Sauvignon: cool climate, water deficit, high nitrogen ➡️ great bouquet with aging.
- Rhone valley in France or the Hawke's Bay area in New Zealand and Syrah: cool climate, high light exposure ➡️ great black pepper aroma.
- Marlborough in New Zealand or Sancerre in France and Sauvignon Blanc: cool climate ➡️ green aromas and grapefruit.
- USA or Australia or Chile and Sauvignon Blanc: warm weather ➡️ passion fruit aroma dominates.
Knowing the correlation between some terroir characteristics and wines can be a great help in blind wine tasting!