Spatial terroir characterization and grape composition in the Southern Côtes-du-Rhône vineyard (Nyons-Valreas Basin)

Abstract

<p style="text-align: justify;">In order for the characterization of terroir in vineyard situations to benefit both viticultural and wine making practices, it is necessary to consider the spatial aspect of the vineyard environment. An exploratory approach at characterising terroir in the Nyons-Valreas Basin (figure 1) considers both the spatial analysis and frequency analysis of the harvest. Data gathered from stereoscopic aerial photographic examination, satellite image processing, land surveys, and the Digital Elevation Model are combined and structured within a Geographic Information System along with the existing soil and geological data (figure 2). The result is a comprehensive soils model applicable to a relatively large area (11,340 ha). The Nyons-Valreas Basin is a neogene and quaternary sedimentary basin, and the soils found there are described by 21 soil landscape units which integrate 15 variables (table I). The area examined is considered to be representative of the surrounding regional diversity. The variables used in characterising terroir include soil types, geomorphology, lithology, stratigraphy, vegetation, land form, and land use. The various viticultural terroirs are regarded as parts of agricultural land consistent with both soil landscapes and harvest/wine responses. Multivariate clustering of the soil landscape units indicates that there exists 7 distinct viticultural terroirs, essentially on the basis of geomorphology and soils (figures 3 and 4, table II). Four distinct terroirs were compared (figures 5 and 6) using data gathered from 14 sites over the course of 15 vintages (1982-1996). Grenache is the grape variety planted at each site, and the variables measured at harvest (pH, sugar content, titratable acidity, the weight of 200 berries, and the sugar/acidity ratio) appear to significantly discriminate the sites examined according to the terroir modeling performed (tables III, IV and V).</p>

Underpinning terroir with data: on what grounds might subregionalisation of the Barossa Zone geographical indication be justified?

“…Nonetheless, the quantitative approach used in the present work, which results in relatively few, albeit discernible clusters, is arguably more useful as a basis for exploring subregionalisation than the thematic and heuristics-based land classification approach of Robinson and Sandercock (2014) and other terroir researchers (e.g. Vaudour et al 1998, Jones et al 2004, Bonfante et al 2011). As noted by Bramley et al (2020), even when based on just AWC and elevation, this more traditional approach resulted in too many classes for Barossa winegrowers to find useful as a guide to understanding 6; that is, clustering of soil cation exchange capacity (CEC) and available water capacity (AWC) with a characterisation of the viticultural season (GDD, season growing degree days; GSR, growing season rainfall) for land under vineyard.…”

“…In the latter study, different results were obtained when viticulturally important soil and climate attributes were clustered just for land under vine, compared to when data for the entire GI were used as is common in terroir zoning research (e.g. Vaudour et al 1998, 2010, Jones et al 2004, Carey et al 2009, Bonfante et al 2011, 2018, Fraga et al 2017. These different results led to a different recommended basis for exploring within-GI wine sensory and chemical differences than one offered on the basis of a 'whole-of-region' analysis (Lacorde 2019, Bramley andGardiner 2021).…”

Making sense of a sense of place: precision viticulture approaches to the analysis of terroir at different scales

“…Thus, for example, Jones et al (2004) assessed the suitability of topography, soil, land use and climate in the Umpqua Valley (Oregon, USA) to identify "the best terroirs of the region". Vaudour et al (1998) used a somewhat similar approach in the Côtes du Rhône (France), and sampled Grenache fruit to demonstrate grape compositional differences between four of the identified terroirs. However, advances in geographical information systems (GIS) and digital mapping have enabled more robust quantitative methods to be developed; Vaudour et al (2015) provide a review.…”

Remote Sensing Data for Digital Soil Mapping in French Research—A Review

“…Observation and hence, understanding the spectral behavior of soil as a function of its composition and structure has been the cornerstone for establishing relationships between the spatial distribution of soil properties at different scales, soil types, or soilscapes, and RS imagery products in the solar (e.g., [61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77]), as well as in the microwave (e.g., [65,70,71,73]) and the thermal infrared (e.g., [59,78,79]) domains. Several studies have also addressed the mapping of soil color (e.g., [46,51,80]) or soil moisture (e.g., [78,79,[81][82][83][84][85][86]).…”