Effect of vine nitrogen status on grape and wine quality: Terroir study in the Vaud vineyard (Switzerland)

This study was conducted on soil-climate-plant relations (terroir) and their impact on grape composition and wine quality in the canton of Vaud by Agroscope Changins-Wädenswil ACW. An assessment of the vine nitrogen status on different terroirs was made by means of chlorophyll index, leaf nitrogen content and yeast assimilable nitrogen. Vine nitrogen status was observed to be highly related to soil type. Vines on the soil type “bottom moraines” showed lower vigour, smaller berries and a lower nitrogen status. Sensory analysis discriminated wines from different soil types. Vine nitrogen status through yeast assimilable nitrogen turned out to be strongly correlated with wine positive sensory descriptors and negatively correlated to wine astringency. In our study, the main environmental factors influencing vine development and wine quality was the soil type via its effect on vine nitrogen level. Our results confirm the role on nitrogen supply in grape and wine quality and underline nitrogen as a key factor in understanding the terroir effect.