Impact of Soil

The soil composition of vineyards is one of the most important viticultural considerations when planting grape vines. The soil supports the root structure of the vine and influences the drainage levels and amount of minerals and nutrients that the vine is exposed to. The ideal soil condition for a vine is a layer of thin topsoil and subsoil that sufficiently retains water but also has good drainage so that the roots do not become overly saturated. The ability of the soil to retain heat or reflect it back up to the vine is also an important consideration that affects the ripening of the grapes.

There are several minerals that are vital to the health of vines that all good vineyard soils have. These include calcium which helps to neutralize the Soil pH levels, iron which is essential for photosynthesis, magnesium which is an important component of chlorophyll, nitrogen which is assimilated in the form of nitrates, phosphates which encourages root development, and potassium which improves the vine metabolisms and increases its health for next year's crop.

There are several tipes of most important  soil:

Clay Soils

Clay soils are made of tiny flat mineral particles that swell when they are wet, so clay holds lots of water and doe not drain well. Clay soils stay cool longer in the spring than looser-textured soils. This causes grapes to ripen more slowly, producing grapes that are more acidic and tannic. Clay soils are highly fertile, transferring more nutrients to the vines. Merlot and Chardonnay grapes do well in clay.

Silt and Sand

Silt has particles larger than clay. Called loess, these soils are found in German Austrian regions that produce white wines. Sand has the largest particles and a loose texture. It ordinarily doesn't hold enough water to produce high-quality grapes. Sand absorbs more sun and is warmer.

Loam

Loam is a combination of silt, sand and clay. It is a rich, fertile soil, high in nutrients and organic matter, and it holds water well. Grapes grown in loam have vigorous vines that can shade fruit, delaying their ripening and lowering their quality. Clay mixed with loam produces even higher vigor and more grapes.

Chalk

Chalk, a type of limestone, is soft enough for roots to grow in and is fairly cool. It holds enough water to nourish vines, yet it drains well. Its calcium content makes it alkaline, producing grapes with a high acid content. Chalk limits the growth of the canopy, helping the grapes to ripen. Pure chalk soils, fairly rare, are found in the Champagne, Cognac and Jerez regions of France.

Granite and Schist

Granite and schist are igneous rocks; schist is a mixture of numerous minerals. Soils formed from granite and schist have loose texture and low fertility but drain well. They are found in Germany's northern Rhone Valley, Portugal's Douro region, and the Beaujolais area of France. Grapes producing Gamay, Syrah and fruity wines with floral aromas grow well in these soils.

Gravel

Soil composed of gravel, largely quartz, is called conglomerate. Gravel causes soil to heat well and drain freely. This is a good soil for Cabernet and other late-ripening grapes but can cause water stress in Merlot and other varieties.

Limestone

The nature of bedrock often determines the quality of a soil. Soils from limestone, ordinarily formed from fossils of ancient marine life, are high in calcium. Limestone soils can form impenetrable layers that block roots. Soils containing chunks of limestone are called calcareous. The term "marl" describes a crumbly mixture of clay and limestone. The Cote d'Or region in eastern France contains a calcareous marl that produces good Chardonnay.