What is Terroir?
Terroir is a term of French origin that we can translate as terrain, terroir, payment … In viticulture the word terroir describes the particular climatic conditions, in a specific geographical location (on a specific soil) and the effects they produce on the grape and later the came.
The weather and geolocation directly influence the characteristics of the wine. Climate conditions have an important impact on the composition of the grape and therefore on the quality of the wine.
We are mainly going to comment on the relationship between climatology and terroir.
Physical effects of temperature on the vines.
Temperature is the most important and influential climatic component in a terroir. It has a great impact on the phenology of the vine, the physiology and the composition of the grape.
It is important to bear in mind that the temperature of the vine does not necessarily have to be equal to the ambient temperature: Vine plants can heat up and have a temperature higher than air temperature, (if they are in the sun and the speed is low) and can also get cold at night.
Some physical effects of temperature on the vineyard:
1, Fruit , dark clusters: dark clusters can reach up to 15ºC above air temperature.
2, Leaves : the temperature of the leaves also rises, but it is compensated by the evapotranspiration of water that occurs through them. Of course, it must have the necessary water availability. In the event that you have the necessary water, the temperature of the leaves rarely increases more than 5ºC above the ambient temperature.
3, During the night , the leaves can have a temperature of 3 ° C lower than that of the ambient air.
The difference in temperatures from one geographical location to another can be an important factor that differentiates the vine, its phenology, the composition of the grape and, therefore, the quality of the wine. It is what we know as the terroir effect .
Sunlight: photosynthesis, evapotranspiration and …
Not only in the vine, but in all plants, sunlight provides the energy to carry out photosynthesis and the evaporation of water through the leaves of the vine (evapotranspiration).
Ultraviolet light can have an impact on the composition of the grape and therefore on the quality of the wine.
According to Richard Smart , ultraviolet light increases the production of some important components in grapes such as polyphenols, which are very important for aromatic compounds and wine color.
Therefore, exposure to ultraviolet radiation has a positive impact on the quality of the wine. Another of the terroirs effects.
Precipitation and rainfall in a terroir.
Rain is one of the three most important components of the terroir’s climate.
Precipitation has two important effects on the grape:
1, Regulation of soil moisture, which directly affects the physiology of the vineyard.
2, Effect on vine diseases .
Humidity, limiting factor for the health of the grape.
Humidity is especially important in fungal diseases. We know that fungi only spread in conditions of high relative humidity, so high levels of humidity will condition the greater existence of fungal diseases.
Other climatic factors of the terroir.
Evapotranspiration is important in determining the water requirements in the vineyard. Evapotranspiration rates are high when there are high levels of sunlight, high temperatures, low humidity, and high wind speeds.
There are other climatic factors, which are not normally considered important in a Terroir such as wind, extreme temperatures (both high and low), snow, hail … that can cause significant stress to the vineyard and therefore in the composition of the grape.
Conclusion on the terroir effect.
There is a very important relationship between microclimate and terroir.
The climate of the vineyard and the properties of the soil have important consequences for the physiology of the vine and the composition of the grape and the quality of the wine .
Each viticulturist must know his terroir. Current viticulture techniques can help “manipulate” the quality of the wine and enhance or soften the effects of the terroir.