Soil Formation 2.1.3 – Explain how natural actions such as weathering, erosion(wind, water and gravity) and soil formation affect Earth’s surface.

Concepts to know: Soil – loose covering of broken rock particles and decaying organic matter. top soil – the uppermost layer of soil. Transported soil – soil that has been moved away from its parent bedrock. Residual soil – soil located above its parent material

Concepts to Know Soil profile – a vertical sequence of soil layers. Soil horizon – A distinct layer or zone within a soil profile. Humus - The organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms

Concepts to Know Bedrock – Unweathered, solid parent rock.

Soil formation starts with… Weathering Erosion Deposition

Then you add in… Some living organisms such as bacteria, fungi and insects. They die, decay and add nutrients to the soil.

And then….. The texture improves as this continues. The soil’s capacity to hold water increases.

Soil Profile This is a vertical sequence of soil layers.

Soil layers A layer – rich in humus and minerals B layer – medium size particles, drainage, poor in humus C layer – large particles; little to no plant or animal life Bedrock - solid

Factors that Affect Soil Formation Weathering (mechanical/chemical) Parent rock composition Climate conditions Topography –slopes, valleys, north/south of the equator

Soil Fertility Factors Mineral and nutrients (humus) availability The number of microorganisms – breathing, water filtration Rain – amount of precipitation/year Topography – elevation Valley more fertile than slope- south more fertile than northern exposure (sun light/rays) Soil acidity

Soil fertility Soil fertility is the measure of how well a soil can support growth of plants. Soil fertility depends on the amount of organic matter in it. Having different sized particles is better for water filtration than uniform size.

Soil Texture Clay – smallest Silt – medium Sand – largest

Can you dig it?!?!?