Soil

The most important benefit offered by soil is also the most overlooked, and that is anchorage. The ability to root the vine into the ground is essential. Beyond that, however, the key element is drainage, Vines don't like to be waterlogged and respond badly in those conditions. Additionally, if drainage is poor and there is heavy rain near harvest, the grapes are likely to soak up extra water and dilute their other components, thus reducing the quality of the resulting wine. Drainage can be modified.

Vines can tolerate quite a wide range of soil pH levels, from about 5.5 (acidic) to around 8.5 (alkaline), but it may be better to adjust the soil at either end of the spectrum, and particular rootstocks may be required to cope with extreme situations. Nutrient content is also critical. Vines need a supply of various elements, most notably nitrogen, but also phosphorus, potassium and various metals. However, excessive fertilizer particularly too much nitrogen-promotes vigorous vine canopy growth that may shade the bunches of grapes and inhibit ripening. Likewise, too much potassium in the soil will reduce the acid level in juice-and consequently in the winemaking it less balanced and stable, and reducing its aging potential. This has been a major problem in the vineyards of Burgundy in the last few decades after intemperate use of fertilizer in the years following the Second World War.

Modern viticulturists monitor soil structure and composition, and moderate water supply and nutrient addition (which often come through the same pipe) accordingly. There is a view, however though it is hard to adduce concrete evidence for it-that the best wine comes from the vineyards which are manipulated the least.

The ideal soil, therefore, has good drainage, with access to retained water at some depth if irrigation is not an option. It should have a balanced texture-neither too much clay, which will waterlog, nor too much sand, which drains well but does not retain nutrients. It has reasonable access to essential elements, but is not so fertile that it promotes luxuriant canopy growth. As well, it should not be overly limey or acidic. In many ways (except for the lime content), chalky soil is close to perfect, but the only substantial wine region where it predominates is Champagne.

One common myth needs to be nailed. There is no evidence that the soil in the vineyard conveys flavor to the wine. Mosel wines may be described as "slatey," or chablis as "flinty," but that is not because slate or flint in the soil imparts flavor, It is possible, though unproven, that chemical component of the soil may influence nuances of taste, but it is not true that soil conveys its flavor to the wine.