A Unique Laboratory to Explore Soil-Wine Relationships, North Canterbury, New Zealand
Abstract
The special character of North Canterbury is a reflection of its geological history - a region of oblique crustal convergence forming northeast striking folds, creating hill, valley and basin topography. Cretaceous to Tertiary glauconitic sediments, limestones, sandstones and weathered conglomerates overlie basement greywacke sandstones and siltstones. During the late Quaternary, erosion infilled valleys with locally sourced sediments, and basins with greywacke alluvium. Calcareous and noncalcareous loess mantles are locally sourced. Detailed soil mapping of vineyards planted between 1980 and 2000 reveal bedrock and colluvial hill slopes with clayey Haplustolls and Argiustolls, fans with deep silty Hapustalfs and terraces with deep alluvium forming clayey Calciusterts and gravels forming Haplustepts. Definitions of terroir variously include physical attributes such as climate, landscapes, soils and vines, together with cultural traditions represented by grape varieties and systems for canopy management, which come together in particular sensory attributes displayed by certain wines. We have recently begun to explore terroir in the context of New Zealand Pinot Noir (the variety considered by many as most able to communicate details of local geography and site). The assessment of wine sensory attributes is not a trivial task. Our experience is that scale is an important influence as ferment size decreases. We recommend the use of commercially produced wines for such studies. Our work has been carried out using statistically valid designs with expert but untrained panelists. In these circumstances the meaning ascribed to particular attributes may vary between panelists but there is evidence to support the contention that expert panelists tend to share a standard vocabulary and are likely to be familiar with appropriate conceptual models of the wines that allow their differentiation. Our results confirm that Pinot Noir wines from climatically differing regions of New Zealand are distinguishable from one another by smell and taste. In these environments, cultural (management) decisions are adapted to maximize so-called physiological ripeness that tend to work against simple relationships between say latitude and mean temperature. Even within the conceptual framework provided by climate as a determinant of berry composition at harvest (and hence, presumably, wine composition), there is a recognition that landscapes and soils are important modifiers, particular of heat and water balance but also of nutrients and uptake of other components through root systems. The contrasting array of soils in North Canterbury provides an opportunity to validate the soil contribution to terroir.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.H53F1589H
- Keywords:
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- 1865 HYDROLOGY / Soils