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Towards meaningful geographical indications: Validating terroirs on a 200 km2 scale in Australia's lower Hunter Valley

Coggins, Sam, Malone, Brendan P., Stockmann, Uta, Possell, Malcolm, McBratney, Alex B.
Geoderma regional 2019 v.16 pp. e00209
climatic factors, edaphic factors, grape juice, landscapes, perennials, protected designation of origin, soil, taste, Australia
Terroir can be loosely defined as the ‘taste of place’. Our ability to create meaningful geographical indications (GIs) is limited by our inability to establish terroirs on a large spatial extent (>100 km2). We performed an investigation to build on previous efforts to quantitatively establish terroirs for Semillon grapes grown in Australia's Lower Hunter Valley (Area ~200 km2). We mapped 10 soil variables, six terrain variables and three climate variables across the entire region to a resolution of 25 m. We clustered these variables, using fuzzy-k-means, to create a single ‘Terron map’ that parsimoniously divided the Lower Hunter Valley into six distinct environments (Terrons). The addition of climate variables and new soil data enabled an improvement on the previously created Lower Hunter Valley Terron map. Moreover, preliminary analysis indicated substantial variation in Semillon grape juice characteristics across the Lower Hunter Valley. We concluded the region covered by the ‘Hunter Valley’ Geographical Indication is more than two orders of magnitude too large to meaningfully reflect terroir. The methodologies discussed in this report could be reapplied to establish terroir and thus GIs for other perennial crops.