What is the elusive ‘formula’ that will allow growers to manipulate wine quality in the vineyard to better express terroir?
That’s the tantalising puzzle a team of researchers are aiming to solve in a long-term project funded by Wine Australia.
It is anticipated that grapegrowers, winemakers and wine brands can use the information to maximise the expression of terroir in wine to help secure a sustainable future for the entire Australian wine sector.
The importance of terroir is twofold: first, it defines the style and quality of the wine; second, it is a fundamental tool to position Australian wines in international markets.
While management techniques can have a significant influence on vineyard performance, there is distinct variation in Shiraz wine style within and between Australian wine regions.
In this project, the team is aiming to understand how the vineyard drivers of wine uniqueness – and thus terroir – work. They also want to determine the marker compounds or chemical profiles for unique Australian Shiraz wines.
The team is researching Shiraz terroir across a range of scales, using six potential sub-regions from the Barossa Grounds program – Northern Grounds, Southern Grounds, Central Grounds, Eastern Edge, Western Ridge and Eden Valley.
At a regional scale, samples have been taken from vineyards and wine from more than 100 sites in the Barossa. Vine, fruit and wine parameters that typify particular regions are being identified and related to the environment.
At the sub-regional scale, 24 sites have been selected and are being monitored in greater detail, including the weather, key soil physicochemical properties, soil moisture, phenology and canopy growth. Fruit has been sampled for maturity, yield and small lot winemaking.
Management interventions have been imposed on selected sites to determine the potential to optimise a site’s terroir.
Wine sensory analysis is also being performed on small lot wines and the wines are then being compared to commercial wines.
Ultimately, the project aims to increase the competitiveness, demand and premium paid for Australian wine.
The project stages
The ‘Barossa Terroir Project’ – a collaboration between the University of Adelaide, South Australian Research and Development Institute, CSIRO, Charles Sturt University and the Australian Wine Research Institute, with support from producers and the Barossa Grape and Wine Association – is one of two researching Australian Shiraz terroir. You can view its partner project at Charles Sturt University here. This partner project is defining the sensory properties of Shiraz wines made outside of the Barossa from selected regions in New South Wales, Victoria and South Australia and identifying the attributes associated with typicality from these regions
The first phase of the project involved establishing field sites and installing weather stations and soil moisture sensing. The second stage involved intensive sampling and capturing measurements.
Preliminary results from this phase indicate that some of the regions have distinct chemical and sensory profiles and these findings were presented to the sector at a workshop held in the Barossa in November 2019.
The project is currently in its third season, with many sites already harvested, or about to be.
This year will focus on bringing these data sets together to address the main aims of the project.
A formal presentation of the results is anticipated for a sector workshop later in the year, ahead of the International Terroir Congress in November 2020 in Adelaide where results will also be presented.