Vine nitrogen status and the terroir effect: a study on cv. Doral in the Vaud vineyard (Switzerland)

A 3-year study was conducted in the Vaud vineyard (Switzerland) to evaluate the effects of « terroir » on the ecophysiology and fruit compostion of Vitis vinifera L. cv. Doral and the characteristics of the wine made therefrom. The impact of soil on the vine-fruit-wine continuum was evaluated at 13 locations in the Vaud during the 2007-2009 seasons. Except for soil, the vineyards presented almost identical climatic characteristics and used similar cultivation techniques. The aim of this chapter was to assess whether soil might be a major environmental factor explaining the terroir effect through its effect on vine nitrogen status. We monitored the nitrogen status of the vines by measuring yeast assimilable nitrogen (YAN) in the must. The soil modulated vine nitrogen status by its fertility and rooting depth. Low vine nitrogen status induced a highly-soluble solids content, low malic acid content and high pH in fruits, resulting in small berries and low vine vigour. Wines were produced in a standardised manner from each location; then, they were subjected to sensory and chemical evaluation. YAN in musts was the parameter that best explained the variation in sensory characteristics of the wine made from grapes from the different locations. Wines made from grapes with low YAN values had negative sensory characteristics such as astringency and low aroma complexity scores. Therefore, vine nitrogen status was a key parameter contributing to the terroir effect. Furthermore, this work provides evidence of how geopedology can influence vine nitrogen status, fruit composition and sensory attributes of wines.