Increase of detail in soil surveys and its contribution for managing wine quality in Vale dos Vinhedos, Brazil

Information on soils is becoming more and more important for viticulture since several factors that influence grape and wine quality are related to soil properties. Soil surveys allow to identify and delineate soil types of an area and to characterize their physical and chemical properties. The mapping scale determines the size of the smallest mappable soil unit and consequently its internal homogeneity, since the more detailed the map is, the more homogeneous is each of the soil units. Therefore, the scale of the survey must be taken into account, when using soil information for managing wine quality purposes. The main objective of this study was to evaluate soil surveys at two different scales in the Vale dos Vinhedos Denomination of Origin (DO), wine production zone Serra Gaúcha, Rio Grande do Sul, Brazil. Second objective was to discuss how the increase in detail of soil surveys may help to improve wine quality and typicity in this region. Material used included two digitized soil maps in scales 1:50000 and 1:10000 and a digital map with georeferenced boundaries of the vineyards at Vale dos Vinhedos. Spatial analysis was done with ArcGIS software. Results showed that in scale 1:50000, the scale used for the previous DO characterization, 14 soil mapping units belonging to 5 orders were found intercepting the vineyards. When using the recently finished soil map in scale 1:10000, the number of mapping units increased substantially, near 10 times, comprising 135 mapping units of 6 orders. The observed variability of soils shows potential to detail even more the characteristics of the terroir. Detailed surveys allow to investigate the variables that affect wine quality, to make the necessary adjustments and to identify homogeneous parcels for separate harvesting and winemaking.