(PD) - As a concept, terroir raises controversy among winemakers and grape growers around the world. There are exceptions, of course, but most European winemakers claim that terroir has a direct impact on wine quality, while winemakers in California, Australia and other new world wine regions believe that wine quality is more the result of other factors than just terroir.

The Oxford Companion to Wine defines terroir as “the total natural environment of any viticulture site.” That definition is as good as any, but the concept is more complex and layered.

Terroir takes its name from “terra,” the Latin word for earth. But the concept is uniquely French . So strong is the belief in the power of terroir that in 1937, the French government determined that terroir would define the set of regulations known as Appellation d’Origine Controlee, which control French grape growing and wine making.

The value the French place in soil was illustrated in the recent purchase of Villa Sorriso, the Mayacamas Mountains estate of the late actor Robin Williams, by the owners of Chateau Pontet-Canet, a fifth-growth Bordeaux. “The soils here correspond perfectly to the style of wine that we hope to make,” Jean-Michel Comme, the chateaux technical director, told Decanter.com.

For the California wine consumer, however, the concept of terroir is more abstract. Some see terroir as nothing more than wine mumbo-jumbo, while others maintain that understanding the total growing environment of a wine grape can add greatly to wine quality and enjoyment. Kimberlee Nicholls, winemaker for Markham Vineyards in the Napa Valley, appreciates the impact terroir has on her cabernet sauvignons.

“I love making cabernet that expresses terroir,” she said. “The volcanic loamy soils in our Calistoga vineyard produce more delicate red-berry fruit with hints of fennel, while the sedimentary gravel soils of our Yountville Vineyard give cabernet sauvignon a more chocolate character.”

Soil is one of three main components that make up the over-arching concept of terroir, the others being topography and climate. There are dozens of soil types scattered throughout the wine regions of the world. A few years back, scientists told me that in the Napa Valley alone there are 33 different soil series and more than 100 soil variations. That new knowledge about soil encouraged me to look further at the impact of terroir on wine quality.