Agriculture Reference
In-Depth Information
Soil Depth
Provided there are no subsoil constraints, the natural tendency of long-lived Vitis
vinifera , on own roots or rootstocks, to root deeply and extensively gives it access
to a potentially large store of water and nutrients. In sandy and gravely soils that
are naturally low in nutrients, such as in the Médoc region of France, the Margaret
River region in Western Australia, and the Wairau River plain, Marlborough
region, New Zealand, the deeper the soil the better. A similar situation pertains
on the deep sandy soils on granite in the Cauquenas region, Chile (figure 6.1).
However, such depth may be a disadvantage where soils are naturally fertile and
rain is plentiful, as in parts of the Mornington Peninsula, King and Yarra Valley
regions, Victoria, Australia, and the Willamette Valley region in Oregon (see
figure 1.11, chapter 1), because vine growth is too vigorous and not in balance.
Although large yields can be obtained from vigorous vines, this is generally at the
expense of fruit quality and the intensity of flavors in the resultant wines. When
vines root deeply in such soils, their vigor should be controlled by restricting the
supply of nitrogen (N) (see chapter 3), regulating irrigation (see chapter 4), grow-
ing a cover crop (permanent, if possible—see chapter 4), and through canopy
management. Figure 6.2 is an example of a soil-vine combination requiring one
of more of these controls.
Figure 6.1 A deep uniform soil profile
formed on granite in the Cauquenas
region, Chile. The pen length is 15 cm.
(White, 2003)
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