Soil and Wine

The concept of terroir as a complex interaction among soil, climate, biology, and human intervention is introduced in section 1.1. The belief that the soil in a par­ticular vineyard imparts a distinctive character to the resulting wine is strong in Europe, but less so in the New World. The special character or personality of a wine may be confined to just one small block, less than 0.5 ha, for example, the “core block” within L’Enclos of Château Latour in the Bordeaux region (Borde­lais) of France. Alternatively, a special character may be attributed more widely to wines from an appellation (the commune Pauillac) or to a subregion such as the Haut-Médoc. But soil is very variable in the landscape (chapter 1), so that as the vineyard area increases, the character of a wine is less and less likely to show a dis­tinctive and defining influence of the soil. Soil variation, in combination with a variation in the mesoclimate (section 1.3.2), will mask a clear, intense expression of the underlying terroir. The grape variety, cultural practices, and the wine maker will then dominate the wine character. Thus, the true influence of terroir can only be satisfactorily studied for small areas. As pointed out in section 8.2.1, soil information is typically collected at a low sampling density over large areas to produce general-purpose soil classifica­tions. The resulting soil maps are necessarily of a small scale (e.g., 1:1,000,000), which means the information about small areas (1–10 ha) is unlikely to be very accurate (see box 8.1). Hence, intensive soil surveys, with at least 6 soil pits per ha, are necessary to study the soil factor in terroir when soil variation can be mapped at a large scale (1:5,000). Further, with more widespread use of precision viticulture technology, as discussed in section 5.3.5, the variation in specific soil properties (e.g., depth to an impeding B horizon and soil strength) can be mea­sured at intervals of about 2 m and mapped at a very large scale (>1:1,000). At a small scale (representing a large area), we can make generalizations, such as that soils on limestone or chalk in Burgundy, Champagne, and the Loire Val­ley in France are highly regarded for producing distinctive wines.