Soil – NOT a dirty word! Soil Formula Soil = inorganic material + organic material + air + water TIME

Soil Texture 4 basic types Sand – feels gritty; packs together when wet but cannot hold shape on its own Silt – feels like talcum powder; flows when wet Clay – feels slick; becomes malleable when wet – can hold any shape Loam – a mixture of all three of the above.

Soil Triangle

Why is Soil Texture important? Determines soil fertility, suitability for construction, etc.

Controls of Soil Formation Parent Material Time Climate Biological Factors Slope

Soil Formation in action – the Soil Profile Definition – a cross–section of soil from the surface to the parent material Since soil-forming processes operate top down, a layering effect eventually develops. Layers in the soil profile are called horizons.

Soil Horizons - TOPSOIL O – (for Organic) includes the organic, or humus layer. A – contains mostly mineral material with some organic material

Soil Horizons - SUBSOIL E – (for Eluviation) – leaching occurs here B – leached material accumulates here, can form a claypan. C – unaltered parent material

Soil Taxonomy http://soils.usda.gov/technical/classification/orders/