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IVES 9 IVES Conference Series 9 Caractérisation des terroirs viticoles champenois

Caractérisation des terroirs viticoles champenois

Abstract

Le vignoble champenois s’étend sur 35 300 ha en Appellation d’Origine Contrôlée dont 30 000 sont en production. Il couvre principalement 3 départements: par ordre d’importance, la Marne (68 % de la superficie en appellation), l’Aube (22 %) et l’Aisne (10 %), et de manière plus anecdotique la Haute Marne et la Seine et Mame. C’est un vignoble jeune (pour plus de la moitié de la superficie, les viticulteurs n’ont l’expérience que d’une seule génération de vignes), et morcelé (plus de la moitié des exploitations s’étendent sur moins de 1 ha; la taille moyenne d’une parcelle cadastrale est de 12 ares). En 1990, le Comité Interprofessionnel du Vin de Champagne (CIVC) a lancé une opération de zonage du vignoble champenois à l’échelle de 1/25 000ème (MONCOMBLE et PANIGAI, 1990). Cet organisme, qui assure à la fois des missions de recherche et de développement en matière viticole en Champagne, s’est alors trouvé confronté à 2 types de problèmes concernant son réseau expérimental actuel:

– il est difficile d’extrapoler les données issues d’une parcelle expérimentale à une zone plus large pour établir des cartes thématiques sur l’ensemble du vignoble. Pour pouvoir extrapoler ces résultats ponctuels, il faudrait définir la parcelle expérimentale par des caractéristiques qu’il est possible de spatialiser, par exemple des unités de terroir.
– il est parfois difficile de répondre précisément par manque de référence à des problèmes que les viticulteurs soumettent au CIVC. Les réponses pourraient être affinées s’il était possible de rattacher avec un minimum de données facilement accessibles (sondages à la tarière, mesure de la pente et de l’orientation, etc.) la parcelle du viticulteur qui pose problème à un site expérimental où les informations sont plus exhaustives.

L’objectif est donc de :
– définir des unités de terroir homogène de manière objective et reproductible,
– choisir, au sein de ces unités, des sites représentatifs où il serait possible d’implanter des observatoires de la vigne. Ces observatoires permettront de décrire et de mieux comprendre le fonctionnement de la vigne, voire de caractériser le type de vin pour une année donnée, en relation avec le terroir.
La mise en place de ce réseau impliquera une reconfiguration du réseau expérimental actuel du CIVC. L’objectif n’est pas de multiplier les parcelles expérimentales, ce qui deviendrait ingérable, mais de concentrer sur une trentaine de sites dispersés dans tout le vignoble un maximum de mesures et d’analyses en fonction des conditions de milieu naturel bien définies. Cela n’empêchera pas de conserver quelques sites expérimentaux plus “légers”, pour mieux comprendre la répartition spatiale de certains phénomènes. L’objectif est d’aboutir à 3 niveaux d’analyse:
– les observatoires qui représenteront le niveau le plus fin, mais dont le nombre sera limité à une trentaine de sites. Ce réseau expérimental sera une plate-forme commune et normalisée d’expérimentation à long terme (10 à 15 ans) et deviendra un véritable outil d’aide à la gestion appliquée des vignes. On peut estimer qu’en une quinzaine d’années, le modèle entre la plante et son environnement, selon un type d’année climatique, sera suffisamment stable et robuste pour être utilisable et extrapolable.
– un réseau d’expérimentation “plus léger” concernant certaines thématiques. Comme précédemment, ce réseau sera normalisé. On cherche en effet à éviter les problèmes d’interprétation des résultats à cause de données manquantes.
– des enquêtes réalisées auprès des viticulteurs qui permettent d’avoir de manière rapide une information spatiale sur l’ensemble du vignoble mais dont l’exploitation est parfois difficile du fait d’un manque de référentiel commun.
Les étapes de notre travail (Doledec, 1995) ont été :
– définir l’objet d’étude, “le terroir”, et informatiser les données disponibles. Le terroir est défini comme un ensemble de facteurs du milieu naturel en interaction (sol, sous-sol, relief). Compte tenu de l’hétérogénéité des parcelles (la superficie moyenne d’une parcelle cadastrale est de 12 ares), il est impossible de prendre en compte l’impact de l’homme, notamment par ses techniques culturales pour l’ensemble du vignoble champenois.
– estimer la qualité du jeu de données. Les données issues de la carte des sols font plus spécialement l’objet d’une étude de la justesse des notations utilisées par les techniciens. La comparaison entre la typologie de solums effectuées par le pédologue et celle issue d’une classification statistique permet d’affiner la carte des sols.
– déterminer les composantes principales des terroirs. Le choix de ces composantes repose sur la disponibilité de données informatisables et sur la connaissance d’avis d’experts mettant en évidence la relation entre des paramètres du milieu naturel et le comportement de la vigne.
– croiser les modalités des composantes principales des terroirs, pour aboutir à une carte des terroirs à 1/25000ème. Cette carte a été comparée à un zonage de la précocité de la vigne réalisé par des viticulteurs sur une commune.
– choisir, d’après la carte des terroirs obtenue, des sites potentiels pour l’implantation d’observatoires de la vigne.

DOI:

Publication date: March 25, 2022

Type: Poster

Issue: Terroir 1996

Authors

ANNE FRANCE DOLEDEC (1), M.C. GIRARD (2), D. MONCOMBLE (1), L. PANIGAI (1), M.C. VIRION (1)

(1) Comité Interprofessionnel du Vin de Champagne, 5, rue Henri Martin, 51204 Epemay
(2) Institut National Agronomique, 78850 Thivervai Grignon

Tags

IVES Conference Series | Terroir 1996

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