葡萄酒社

World of Wine—Vineyard Site selection

DR CASSANDRA COLLINS:
 

Site selection is a very important part of developing a vineyard.
When we select a site in the best possible environment for a particular wine style the commercial cost of making a quality wine is lower.
In most seasons at the ideal site the grapes will be of sound quality and naturally well balanced for the desired wine style.
This means that the need for technical intervention in the winemaking process is reduced.
Site selection is dependent on a number of factors related to vine performance.
And these factors include how much yield is required, the wine quality and style to be produced, and the cost of production.
An understanding of the soil, topography, and climate of a particular location forms the basis for choosing favourable viticultural sites.
This knowledge allows grape growers to not only produce better quality grapes in traditional wine producing regions, but also to expand production into new areas or make an informed decision to not select some sites due to undesirable properties such as an area that has very high frost risk.
One of the main features of many vineyards known for high quality grape production is their limited soil fertility.
If soils are too fertile this can result in very dense canopies due to a large amount of vegetative growth.
This can be at the expense of fruit production and lead to shading of fruit and less air movement through the canopy, resulting in high levels of disease and problems with sugar and flavour development in the fruit.
Excellent soil drainage is another feature of many vineyard soils.
Good soil drainage promotes early spring growth and limits berry splitting following heavy rains, therefore reducing the amount of disease that can develop.
Topography and aspect are two other factors considered in site selection.
For example, if a vineyard is planted on a slope you can reduce the risk of frost, improve soil drainage, increase light interception into the canopy, and decrease temperature variability.
One important factor we haven't mentioned is climate, which plays a large role in site selection.
Temperature is arguably the most important climatic factor, as it affects the growth and development
of grape vines, and hence berry ripening and grape quality.
For example, cooler conditions are known to retain fruit acidity which improves the microbial and colour stability
of wines.
The cool conditions also appear to favour the development and retention of grape aroma compounds.
Higher temperatures, on the other hand, generally result in higher sugar levels and reduced acidity.
Because taste, colour, stability,and ageing potential are all influenced by grape sugar and acid content, temperature conditions throughout the season have a large affect on grape quality at harvest.
Sunlight is also important, and affects the number and development of bunches.
Generally, some exposed buds produce shoots with more inflorescences and more flowers per inflorescence than buds developed under shaded conditions.
Although sun exposure is usually beneficial, excessive exposure can result in the berries being sunburned,
which can generate negative flavours in the wine produced from those grapes.
In all climates it is important to get the ideal exposure to sunlight and temperature, which can enhance soil warming and reduce frost severity.
When we achieve this, fruit ripening is often advanced and berry colour and the sugar-acid balance improved.
Ideally, vineyards also have medium to low rainfall.
This is mainly because dry conditions reduce the risk of pest and disease problems.
In many wine regions, most of their rainfall is during the winter months.
This means that there is sufficient soil moisture in spring for early growth.
However, during the summer the vines may be exposed to varying degrees of water stress, which can be both detrimental and beneficial to development.
To avoid water stress at key developmental stages such as in the spring and early summer,
we apply water using irrigation in areas where it is needed.
Other factors, such as wind and humidity, are also considered in site selection, as these can impact on the level of disease and physical damage that occurs to the vines.
Once we've selected the best site to plant a vineyard, we need to consider the design of the vineyard to maximise the environmental benefits.
This design will include the orientation of the rows, the type of trellis system we use, and the type of management practices we apply.
Some aspects of this design will be shown in the vine management video later in this course.
 
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