Soils – Types and Classification.
In viticulture, determining which grapes to plant in which soils play a major role. A deeper dive in Pedology-study of soil and Edaphology- the study of the influence of soil is very important to have a flourishing vine and someday a great wine from that vine. A soil type influences the quality of wine and is considered an integral part of the terroir. Therefore understanding a soils colour, depth, organic composition, pH, drainage etc. is crucial.
Soil is one of the major components of the Earth’s ecosystem. A typical soil is about 50% solids (45% mineral and 5% organic matter), and 50% voids (or pores) of which half is occupied by water and half by gas. For soil to form from rocks, it takes an average of 500 years or more. Soils can be broadly classified into 4 different types.
- Sandy Soil.
- Silt Soil.
- Clay Soil.
- Loamy Soil.
Other than these soils various
combinations and mixtures give rise to numerous soil types.
Sandy Soil
Sand comprises of tiny sediments of disintegrated
rock. Sandy soils are very poor in the organic matter content thus very low in
nutrients and poor water-retaining capacity. Sandy soils have good
drainage and retain heat. Sandy soils in wet regions can be a blessing and a
curse in dry regions with drought. Sandy soils retain more heat and less
moisture thus removing the possibility of diseases. Another major benefit of
sandy soil is that it is resistant to phylloxera. Sandy soils
generally produce aromatic wines with low tannins and pale colour.
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| @Sandy Soils |
Regions - Bordeaux’s Medoc and Graves, Colares in
Portugal, Cannubi in Barolo
Silt Soil
Silt is usually finer than sand,
slightly porous, and is made up of rock and other mineral particles, which are
smaller than sand and larger than clay. Silt has good water retention which at
times is not favourable in vineyards as it can cause fungal and bacterial
diseases. The silt soil is more fertile compared to the other three types of
soil and can be too fertile for quality winemaking. Silt produces wines with
lesser acidity.
Loess is one good variety, which is a wind-blown type of silt with high proportions of silica.
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| @Silt Soils |
Regions - Oregon,
Washington
Clay Soil
Clay soils have the finest particles and are tightly packed together with very little or no airspace. Clay has extremely high water retention property and can store water for a longer period of time. This at times helps to keep the vines cooler and in warmer climates, clay soils retain moisture. Clay soils produce bold and full-bodied wines.
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| @Clay Soil |
Regions - Barossa Valley, Pomerol
Loamy Soil
Loamy soils are considered to be the
most ideal soils for vine growing. It is a mix of sand, silt and clay with
benefits from each soil type in one. This soil has good drainage along with a moderate
amount of water and nutrients and has favourable pH levels because of its
inorganic origins.
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| @Loamy Soils |
Favourable grapes – Pinot Noir
Regions - Sonoma
Valley, Napa Valley
Limestone Soil
Limestone is found in many famous wine
regions and is usually associated with quality winemaking. Decomposed marine creatures
helped in forming limestone. Limestone has good drainage but also retains
moisture. Limestone also reflects sunlight which makes it beneficial for photosynthesis.
Limestone based wines have high acidity.
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| @Limestone Soil |
Regions – Burgundy,
Champagne
Volcanic Soil
Volcanic soils as the name suggests are
results of cooled magma from ancient or new volcanic eruptions. The soils are
black and retain heat while providing good drainage and decent water retention.
These soils are rich in minerals like iron, calcium, magnesium, and potassium. The
wines do have a rustic taste to them.
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| @Volcanic Soils |
Favourable grapes – Assyrtiko, Nerello Mascalese
Regions – Sicily, Santorini
Article by - Kevin Rodrigues, Certified Sommelier.
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