How much of a role does soil play in the health and vigor of winegrapes and, ultimately, in the quality of wine?
Like so many things vinous, it depends on whom you ask.
Let’s start with the French. In France, soil provides the very basis of quality assessment and plays the key role in the concept of terroir. In fact, the country’s entire appellation controlee system is based on terroir – and, by extension, soil. It’s no mere legend or exaggeration when we hear of an experienced French vintner who can tell where the grapes were grown simply by smelling the finished wine.
Keep in mind that through much of recorded history, the vineyards of Europe – and, in particular, France – were quite small. Thus, over years and decades, recognizable traits could be identified in the finished wines. Quality levels also varied, so certain sites were considered more “noble” than others, and the roles of soil and terroir were underscored.
In the New World, the role of soil plays second… or perhaps even third… fiddle to the differences in regional climate, known as the macroclimate. U.S. wine regions are defined by their air temperature ranges and the number of days of sunshine they receive per annum.
Still, soil plays an important role, but not for the reason you may suspect. It’s not so much about the soil’s nutrients as its draining capabilities. Ultimately, the best soils for growing grapes allow a steady flow of water to the vines – but only a moderate amount.
The best grapes for making wine come from “stressed” vines. Too much water results in too much vine vigor, and grapes that are “watered down” in flavor. So, when planting grapevines, growers and vintners look for the presence of drainage-assisting stones and rock in the soil.