The Soil Component of Terroir

Evidence for a specific effect of soil mineral composition on wine character is largely anecdotal. However, soil potassium supply to the vine must be properly balanced between deficiency and excess for good fruit quality. Nitrogen supply interacts with soil water to affect vine vigour, yield and fruit quality. With irrigation, water availability in the top 40-60 cm of soil can be managed through regulated deficit irrigation, thereby subduing the mineralization of soil organic N and decreasing vine N uptake, with favourable effects on fruit quality. In dry land vineyards, water availability depends on climate and soil physical properties, the latter being beneficially modified by calcium. The effect of soil variation on terroir should be evaluated on a scale of metres rather than kilometers. High density real-time measurements of relevant soil properties enables digital soil mapping at very high resolutions. Thus, vineyards can be divided into small blocks with the same mesoclimate allowing site-specific soil management and cultural operations (precision viticulture).