Soil and Wine - Soils for Fine Wines - page 222

ley in France are highly regarded for producing distinctive wines. French scien-
tists such as Seguin (1986) and Pomerol (1989) attribute this character to the
soil's physical properties —the structure, the rate of water supply to the roots, and
drainage. Chemical properties are considered less influential, provided that the nu-
trient supply is balanced (no surpluses that promote excess vigor or toxicity, and
no serious deficiencies). In the New World, Gladstones (1992) argues that rocky
and gravelly soils produce the best wines across a wide spectrum of climates. Be-
cause soils with stony surfaces are found on the lower slopes of hills (often formed
on colluvial material), most of the best sites are on such slopes, rather than on the
plains or lowlands. Gladstones suggests the best sites are on slopes with excellent
air drainage, on slopes that face the sun directly for part of the day, even in hot
areas, are frequently close to water, and preferably on the sides of projecting or
isolated hills. These are all factors that tend to minimize temperature variation
during the day and maintain higher temperatures at night and in the early morn-
ing. Gladstones could have added that rocky and gravelly soils are also often low
in nutrients.
However, Halliday (1993) contends that in Australia the prevalence of a sum-
mer drought induced a change from the traditional European preferences for sites
and soils. Vineyards on sunny slopes of shallow, calcareous soil did not prosper,
so vineyards on deep alluvial soils in valley bottoms were preferred, as was the case
in the Hunter and Barossa Valleys (also the Napa Valley in California). Now that
irrigation, especially drip irrigation, is more widely practiced, vineyards in pre-
mium wine-growing regions such as these have expanded upslope. The yields are
lower, but the quality is generally higher.
The prime aim in viticulture is to achieve the maximum production of qual-
ity fruit per hectare. Depending on the marketing strategy, the vigneron strikes a
balance among yield per vine and yield per hectare, the quality of the fruit, and
the intensity of berry flavors. The key philosophy in France is that the best fruit,
of most intense flavors, comes from vines with a limited yield. For example, Seguin
(1986, p. 865) states
In general, everything happens in the Bordelais as though the
temperature and the degree of sunlight enabled the synthesis of a limited
quantity of colouring matter, aromas and sapid elements, and it seems that
these substances are diluted and deteriorated when there is too sharp an
increase in yield.
In many of the best French appellations, the wine yield is limited to 35 hL
(ca. 5.8 t/ha). Wine produced from irrigated vineyards is not accepted for the top
AOC category. However, many vignerons in the New World, notably Australia,
believe that intensely flavored fruit of high quality can be produced from high-
yielding vines, provided the vines are “in balance” (Smart and Robinson 1991).
The concept of vine balance is discussed in box 9.1.

Defining the Terroir

9.2

As indicated previously, terroir denotes more than just the relationship between
soil and wine character. Wilson's (1998) book Terroir was subtitled The Role of