Loam

Loam is a combination of Sand, Silt and Clay.

Loam is considered the best soil for almost any type of plants:

• It is granular
• It retains water
• It have good drainage
• It contains organic matter

Loam can be too fertile for vine grapes that need more difficult soil to struggle with.

Pros:

• Good drainage
• Very fertile
• Retains nutrients and water

Cons:

• Too fertile for vineyards

Vineyard Loam

The magic of loam is that sandy loam, clay loam, and silt loam make up some of the the greatest wine soils in the world. Sand helps drainage. Clay has nutrients and water-holding capacity. Silt helps with both heat retention and water holding.

Pinot Noir thrives well with this blend in Napa Valley and Sonoma Valley (USA).<(p>

On the picture below, you will see 3 layers of loam:

• Surface is dark brown fine sandy loam
• Subsurface is pale brown fine sandy loam
• Subsoil is red clay loam and sandy clay loam

Source: Wikipedia Commons.

Silt

Silt is found in river valleys.

It is a granular material of mineral particles smaller than sand and larger than clay.

Silt is more fertile than sand, hold moisture well, but is prone to compaction (similar to clay), which can affect drainage and aeration. With proper management, silty soils can be suitable for vine cultivation.

Silt produces: Smooth wines with low tannins.

Grapes:

• Pinot Noir
• Grüner Veltliner (Austria)
• Pinot Gris (France)

Best known Regions:

• Washington (USA)
• Willamette Valley (Oregon, USA)

Loess

Loess is a sediment of accumulated wind-blown dust of sand and silt cemented by clay and lime.

It is defined as 20% clay with roughly 40% sand and 40% silt.

Loess is pronounced luss and means "loose". It is commonly known as "brickearth" in the UK.

Loess is porous and permeable, great for root penetration, and full of nutrients giving minerality to the vines. It is very fertile and has good water retention and warming properties, but drains poorly.

Best known Regions:

• Nahe, Pfalz, Rheingau and Baden (Germany)
• Wagram (Austria)
• Walla Walla (Washington, USA)
• Hawkes Bay (New Zealand)