Geology and wine 15. Producing wine at altitude: The terroir of São Joaquim, Brazil

Abstract

The municipality of São Joaquim, located in the Planalto Catarinense viticultural region, is the coldest wine-growing region of Brazil, and contains the highest-altitude vineyards in the country. These vineyards were established within the last 20 years, so this is a young and still-developing viticultural region. Information on the terroir of São Joaquim is needed in order to identify potential vineyard sites and to help improve the viticulture in the region. This work aims to characterize the terroir of São Joaquim, where wines are produced from grapes cultivated above 900 m of altitude, through a description and analysis of meteorological, physiographic, pedological, geological and viticultural factors. With respect to these factors, the São Joaquim region presents the following characteristics: 1 It has an annual mean temperature of 13ºC, annual mean precipitation of 1680 mm/year and an annual mean solar radiation of 1832 hours/year. 2 It has altitudes between 715–1638 m and generally steep slopes, 43% of the slopes have declivities between 20–45% and show no preferred orientation. 3 It has both deep (> 150 cm) and shallow (< 100 cm) soils with clayey texture, an average pH (water) between 4.68– 5.52 and an average soil organic matter (SOM) content of 6%. 4 It is underlain by two units of volcanic rocks. These are a mafic unit (50.53–55.09 wt.% SiO2) and a felsic unit (66.58–70.12 wt.% SiO2). The mafic unit tends to consist of thicker flows than the felsic unit and is characterized by generally steeper slopes. 5 There is a correlation between the geological unit and the soil types, in which thicker inceptsols are preferentially developed on the mafic volcanic rocks and thinner entisols are preferentially developed on the felsic volcanic rocks. 6 Currently, the region produces more than 27 grape varieties planted mostly on the Paulsen 1103 rootstock. The existing vineyards are mostly underlain by the mafic volcanic unit in areas of steep north-facing slopes. This preliminary study suggests that there are correlations between the bedrock, the soils that they give rise to and the declivities of the slopes. Knowledge of these relationships should assist in the evaluation and planning of future grape and wine production.