Study and valorization of vineyards “terroirs” of A.O.C. Cahors (Lot, France)

In the current context of market competition and consumption evolution, it is necessary to produce wines of a genuine typicity. The Terroir represents an unique and irreproducible inheritance that can be valorized through the origin and the sensory characteristics of the wines.
Since 1989, the Expérimental Association of « la Ferme Départementale d’Anglars-Juillac » has led research and experimentation on vineyard terroirs, aimed at direct valorization for the winegrowers. The objective is to know (1) the wine-producing potentials of each terroir of the Cahors Appellation, for the principal vine grape cultivars of the Appellation: Malbec N or Cot N or Auxerrois N, (2) the vine behaviour on these terroirs and (3) to valorize this knowledge through technology, agronomy and enological procedures adapted to each terroir.
Cartography of the whole A.O.C. Cahors has been realized (22000ha). Nine terroirs have been identified according to the type of soil and the landscape situation: alluvial terraces of the Lot, “grèzes”, calcareous hillsides, high calcareous plateaus (eventually with marl), and red clays from sidérolithique formations. Agronomic and enological studies of a representative parcel of each terroir have been done since 1994. Pedological pits have also been done with physical and chemical analyses of each described horizon. Each year, maturity controls are carried out on these parcels; each is separately vinified with the same protocol. Wines are analyzed and tasted.
Results show that qualitative terroirs exist on alluvial terraces of the Lot, as well as on high calcareous plateaus. It is not the chemical nature (acid or calcareous) of the soil but the thickness of the soil which determines the quality of a terroir, in relation with the regularity of vine hydrous nutrition. For all that, some terroirs seem well adapted to produce vintage wines, whereas other terroirs seem more adapted to produce regional wines or wines for blending.
This study provides an agronomic and enological basis for advising wine-growers, in order to lead each terroir to its qualitative optimum: adaptation of the cultural practices, especially for new plantations (choice of the rootstock, soil management); adaptation of the method of vinification according to the terroir. The wine-grower has to take care of the terroir, the quality of the grape harvested and the wine. This study has led to a qualitative improvement of A.O.C. Cahors wines. The Cahors Appellation is now experiencing an infatuation for the most qualitative terroirs.
In the future, the start-up of the hierarchical system of the A.O.C. Cahors terroirs and the creation of vintage wines, will allow a large communication on wine quality and typicity, favorable to the whole Appellation Cahors wine business.