Agronomical assessment of a vine « terroir » map: first results in the « AOC » Minervois region

Minervois is a vine region where the first detailed soil map was begun 30 years ago. In 2003, a new map was drawn plotting the soil-landscape associations. This map distinguishes 8 large soil units based on geology. The widest (called « marnes ») is the most complex : it is made of 57 sub-units, which leads to a high variability of the vine behaviour on this unit. We proposed a way to simplify that very complex soil information in order to understand the relationship between vines characteristics and the map sub-units of soil. The 57 first sub-units were turned into 5 new ones. Water constraint and agronomical data were examined for 2 vine cultivars on 47 vine plots among the « marnes » unit and compared to 3 of our simplified sub-units (87% of the total area of the « marnes » unit). Shoot elongation and carbon discrimination were used for estimating water regime during summer. The soil-plant water regime is revealed to be the main factor classifying the 3 sub-units : we show good relationship between grapes and vines characteristics and the new sub-units.