Agriculture Reference
In-Depth Information
stone soils of St. Emilion and the Côte d'Or. Thus, good drainage during the
winter and regulation of the water supply to vines during the summer are the
salient soil factors governing fruit quality and wine character in the Coonawarra.
The Barossa Valley of South Australia
The Barossa Valley, probably the best known wine region in Australia, has a wine-
making tradition going back to the early 1840s. With the contiguous Eden Val-
ley, it comprises the GI Barossa Zone. The Barossa Valley occupies the land on
the western slopes of the Barossa Range and the valley below, to the northeast of
Adelaide. The average elevation is 274 m, and the annual rainfall is between 500
and 550 mm. The Eden Valley lies to the east, at an altitude
400 m. The Zone
grows red grapes, mainly of the varieties Shiraz (Syrah), Grenache, and Cabernet
Sauvignon, and white grapes of the varieties Semillon, Riesling, and Chardonnay.
The Eden Valley produces wines more in the cool climate style, including Shiraz,
Riesling, Chardonnay, and Pinot Noir.
The rocks of the Barossa Range consist of a belt of metamorphosed Cam-
brian limestone within the gneisses and granites that form the higher elevations.
The valley is filled with colluvial and alluvial sediments derived from these rocks.
By virtue of their mode of deposition and the variety of surrounding rock types,
the Barossa Valley soils are extremely variable (compare to the Napa Valley). Ac-
cording to Northcote et al. (1954-59), the soils at the lowest elevations are mainly
grey and brown clays that are not well suited to viticulture. At slightly higher el-
evations, typically in undulating country, the dominant soils are deep Red Brown
Earths (with calcareous subsoils) interspersed with Solonized Solonetz and other
duplex soils with sodic features (see box 9.2). The Red Brown Earths are the most
favored soils for viticulture, with vines on the Solonetz soils suffering water stress
unless they are irrigated.
Partly because of the complex soil pattern and the practice of large corporate
wineries producing crossregional blends to ensure consistent varietal wines, the
soil has not been featured as an important component of the Barossa Valley ter-
roir. However, the Barossa Valley is renowned for its robust red wines, in partic-
ular those made from Shiraz grapes, such as Penfolds Grange (formerly Grange
Hermitage). The key factors in the quality of fruit and rich, distinctive flavors of
the wines, particularly those made from Shiraz and Grenache, appear to be the
age of the vines (up to 100 years), and the absence of irrigation (see table 9.1).
When the vines rely solely on the supply of soil water, vigor is restrained, yields
are relatively low (
7.5 t/ha), and fruit quality high.
9.7.2
The Heathcote and Nagambie Regions of Victoria
The Heathcote Region is a small area in central Victoria that has some similari-
ties with the Barossa Valley, because it has a reputation for intensely flavored Shi-
raz and Riesling wines. The annual rainfall is 550-575 mm, with cold wet win-
ters and hot dry summers. However, the distinctive feature of many of the
vineyards is the deep, well-structured Red Cambrian Soil (fig. 9.12). The Cam-
brian rocks (ca. 550 million years old) are a volcanic intrusion, only a few kilo-
meters wide, which consists of basic dolerite and diabase outcropping with cherts
and conglomerates. The most highly prized wines are produced from unirrigated
vines, such as at Jasper Hill, where the target yield is only 1.2-2.5 t/ha.
9.7.3
