The Map of Potential Must Weights as an Objective Basis for Characterizing Vineyards in the Rheingau Wine-Growing Region

Although vineyard location has been a traditional and important aspect of German viticulture for a long time, it is not included as a quality-determining factor in current Wine Directives. In the wake of current endeavors to harmonize the regulatory framework within the EU, German legislation is expected to take into consideration the importance of geographical position for differentiating wine quality. Solar radiation and temperature are the limiting climatic factors along the northern margin of the wine production zone. The water budget in a vineyard also has an effect on quality in years with long dry periods. In areas with less than 550 mm annual precipitation, the proportion of dry years can increase to about 40 %. The basic data was collected in a long-term site-monitoring program published by ZAKOSEK et al. (1967). Current geographic information system (GIS) technology can be implemented to obtain spatial distribution patterns of the climatic and pedological factors affecting must weight. The map of potential must weights of the Rheingau establishes specific areas where soil and climatic conditions enable the production of high-quality wines. The calculated must weights only apply for Riesling grapes.