Soil and Wine Quality: Physical soil attributes

Scientific opinion now almost universally agrees with Seguin’s conclusion that soil physical characteristics predominate as the main influence over grape and wine quality other than climate; and further, that, among the physical characteristics, the most important are those which govern water supply to the vine. These and their relationship to individual soil types are discussed in some detail under terroir. See also soil water, soil texture, drainage, and vine physiology.

Here we may note briefly that the best wines come from soils that are very well drained, and furnish a steady, but only moderate, water supply to the vines. When combined with appropriate restrictive mineral vine nutrition, this ensures that growth is restrained. The leaf area, especially the secondary leaf area on the lateral shoots, remains relatively small, and nearly all leaves and bunches are well exposed to sunlight. Smaller berries are also usually less liable to congestion and compression within the bunch, and are therefore less likely to split or suffer spoilage as a result of fungal diseases or bacteria. water stress needs to be just enough to attain these ends, and not enough to reduce photosynthesis too much.