Definition - What does Calcareous Soil mean?
A calcareous soil is a soil that has high levels of both magnesium carbonate and calcium that reduce acidity in the soil. Calcareous soil can have a coarse to fine texture as well as differing levels of sand, silt or clay.
This soil type typically maintains a cooler temperature, has a moderate to high alkalinity, and the soil can balance water retention with drainage.
WineFrog explains Calcareous Soil
Calcareous soils are found in some of the world’s most well-known wine regions such as; Champagne, the Loire and southern Rhône valleys, Burgundy, Chablis, and Saint-Emilion in Bordeaux in France and are credited with producing some of the world's finest wines, mostly due to the high levels of calcium and magnesium carbonate.
The calcium and magnesium carbonate are compounds from limestone that has decayed and becomes accessible to the vine. Not only are the compounds beneficial to the vine, they also lend other attributes to the soil that produce juicy sweet wine grapes. Calcareous soils are well known to drain well, so the roots are not left in water while also retaining moisture, the porous or coarse texture of the soil allows vine roots to grow down and out to reach the water.
These soils also do not hold heat and as a result of the cooler temperatures, the grapes ripen more slowly allowing them to develop more acidity, tannins and flavor.