This post will really only appeal to wine nerds!  But understanding the different kinds of soils will give you a good foundation (sorry) and insight into the wine-making process.  Here’s a list out the soils that are the most prevalent in South Africa.

Best Vineyard soils.

Gravelly or rocky soils are potentially good vineyard soil as gravel acts like natural mulch, shading the vine roots from the sun.  The gravel and clay combinations acts like a sponge storing water during the rainy season and redistributing it back to the roots in the dry season.  This ensures constant feeding for the vines, giving them a more balanced water source as opposed to simple irrigation.

 

Sandstone

sandstone

Lightly coloured, sandy with low nutrient and adequate water retention properties.  Contains calcium and quartz.

Clay

Acidic.  Retains water and is cool – beneficial in warm conditions.  In high quantities, prone to compaction and poor root development.

Granite

granite

Red or yellow-coloured, acidic and found on mountain foothill slopes and ranges of hills; good physical and water-retention properties.  Quartz-rich, hard and acidic, easy-draining, low fertile soil.  Some of the best soils for viticulture.

Limestone

limestone

Alkaline, easy draining, calcium rich soil.  Best suited to white cultivars (Chardonnay).

Shale

shale

Brown in colour, strongly structured, with good nutrient reserves and water retention.

Loam

Equal parts of clay, silt and sand; potential too fertile for grape cultivation.

Gravel

gravel

Free-draining (beneficial in wet conditions), low-fertility, pebbly soil, retains heat of the sun and extends ripening beyond sunlight hours.  Also retains moisture to cool soils.

Sand

Low fertility.  Drains very well, prone to dryness, no storing of nutrients.  Advantage of deterring Phylloxera beetle.

Alluvial

Found on river banks and in flat land previously linked to a river.  Potentially very fertile, yet sandy and silty.  Not suitable for vigorous growers such as Shiraz.