Concepts of Terroir: Winegrapes and the Environment.

The world's greatest wines are the result of a threefold synergy among grape variety, human input (in terms of choices about viticulture and wine making) and the terroir (often defined as the vineyard site, soil and mesoclimate). Terroir is a unifying theory encapsulating an approach to wine that encompasses the interrelationships of soil, climate, and human activity. As a philosophy it often clashes with the reductionist new world grape-variety and 'winemaker'-dominated approach. How do soils affect the flavor of wine? Grape vines are known to prefer well drained soils. Soil surface color is another important physical property. Darker, gravelly soils absorb and radiate heat, storing solar energy during the day and then slowly radiating it back to the vines at night. The chemical soil composition is also important. Plant essential nutrients in the rhizosphere have been shown to alter plant metabolism. For example, magnesium and iron are important components of the chlorophyll molecule. Plant carbohydrates cannot be produced via photosynthesis if these two nutrients are deficient in the vine and soil. Several past studies of terroir have concentrated on the flavor components of the wine as related to the vineyard environment. For example, wine evaluators have tasted wines made by the same winemaker from Syrah grapes grown in different regions: and the wines tasted completely different. Therefore, these sorts of site-specific or regional differences are at the heart of the terroir concept. Six approaches to terroir include plant growing (agro-terroir), winemaking (vini-terroir), territorial terroir, identity terroir, promotional terroir, and legal terroir.