Dividing agrarian exploitations into microfields is a problem that influences the modern viticulture in a very important way. The aim of this work is the study of the influence of Geology and Geomorphology in agricultural structures, and more exactly applied to viticulture microfields, as determining factors in evolution and development of certain Appellation of Origin (AO). The field division of three AO in the Northwest of Spain (Toro, Bierzo, Arribes) is compared. These three regions were chosen because they have similar influence elements.
The Toro AO (total area 76.076,43 ha; vineyard area 4.887,12 ha) is located to the West of Duero river basin and it is formed with limestone and carbonated detritic materials from the tertiary series and with the materials from the glacis and the medium and low terraces of the own river. In this context the altitude difference is small (650-825 m) and the shapes are flat and smooth in the quaternary relieve and undulating in the link tertiary surfaces with slopes under 20%. There are neither rocky outcrops nor stoniness to block the crop technical development.
The Bierzo AO (total area 142.672,08 ha; vineyard area 3.785,33 ha) is located in a sinking intermontane depression basin that is filled up with terraces materials, plioquaternary piedmont which are locally linked through tertiary detritical series with quartzite and schist materials that end in the primary mountainous edges due to basin close. The difference among cotes is important (525-1100 m) and the slopes are very changeable; flat in the alluvials, medium and high in the tertiary relieves and very high in the mountainous ones. Only in the mountainous basin edges there are some zones with rocky outcrops that block the crop technical development.
The Arribes AO (total area 101.969,94 Ha, vineyard area 1.66679 Ha) is located in an erosive surface that includes a whole of deep incisions and canyons of the Duero and its associated systems. In this surface the granite materials and schist, gneiss and quartzite paleozoic materials are predominant. These materials are locally covered with rests of glacis and quaternary materials and these filled up some depressions. The relief is very varied, from soft undulating surfaces in the erosive zone to vertical walls related to the incisions. In the whole AO the rocky outcrops and the stoniness make up or have made up an obstacle to the crop technical development.
Even though in the three AO a selection of the medium size is appreciated, the vineyard medium size is more than two times smaller in Toro AO (2.84) and in Bierzo AO (2.84), but more than five times smaller (5.54) in Arribes AO. On the other hand, while in the Toro AO, the wine-grower can select the better quality zones and zones with a proper structure and a independent of the considered elements, in Bierzo AO and in Arribes AO the vine-growers election possibilities are much lower or there are problems with the slopes which are often in relationships to the soil small effective depth, or if these problems have been eliminated by the effort through centuries the microfields division impede the vineyard crop technical development; the vineyard medium size is more than ten times higher in Toro AO, than in Bierzo AO and Arribes AO.
Authors: Vicente GOMEZ-MIGUEL (1), Vicente SOTES (1)
(1) Universidad Politécnica de Madrid (UPM). Avda Complutense s/n. 28040-Madrid, Spain
Email: vicente.gomez@upm.es; vicente.sotes@upm.es
Keywords: terroir, zoning, landscape, geology, microfield, Appellations of Origin, Spain