Agriculture Reference
In-Depth Information
Wine
grapes
Soils
0.7
Terrain
0.1
Climate
0.2
Spring
Heat degree
days
Flowering
season rain
Ripening
Branas
index
pH
Drainage
Texture
Sodicity
Depth
Slope
Aspect
frost
season rain
0.094
0.184
0.044
0.184
0.495
0.857
0.143
0.073
0.461
0.141
0.282
0.043
An Analytical Hierarchy Process for deciding the biophysical suitability of sites for growing
wine grapes. Note that the weights in each group at each level of the hierarchy sum to 1
(redrawn from Itami et al. 2000).
Figure 8.1
ability of the fruit to accumulate sugar and anthocyanins and to attain a favorable
acidity. The index of precocity for veraison ( IPV ) is calculated for a site i as
V m V i
V m
where V m is the mean date (in Julian days) of veraison for all sites studied, and
V i is the veraison date for site i . They found that “early” sites (with a desirably
high IPV ) typically were on sandy and gravelly soils that were well drained, whereas
“late” sites (low IPV ) were on clayey and silty soils that had perched water tables
in winter. Tesic et al. (2002) obtained similar results for potential Cabernet Sauvi-
gnon sites in the Hawke's Bay region of New Zealand (with a uniform, cool mar-
itime climate). These authors developed a site index for the region based on max-
imum rooting depth, topsoil gravel content, and soil texture (a determinant of
soil temperature), as well as the key climatic variables of growing season rainfall
and mean air temperatures in October and January.
Although determining the site is only the first step in a chain of events in
wine production, it is important because suitable land for vineyards is becoming
scarce in many existing wine-producing regions. Also, the investment per hectare
in setting up a new vineyard is high, so mistakes made in site selection and prepa-
ration can be very costly. The importance of climate and topography in site se-
lection has been discussed by others, such as Gladstones (1992). This chapter dis-
cusses techniques for gathering soil data, and how soil and related properties are
relevant to site selection and soil preparation for vineyards.
IPV i 100 1
(8.1)
Steps in Site Selection
8.2
Soils Types and Their Distribution
As pointed out in box 1.3, soil scientists have typically developed general-purpose
classifications to group like soils together, creating soil classes or types . The out-
put of classification is usually a map showing the distribution of soil classes, with
a map legend that describes the central properties of the major classes. However,
these maps may not provide information, at an appropriate level of detail, on soil
properties important for viticulture. First, there is the question of map scale and
8.2.1
 
 
Search WWH ::




Custom Search