Understanding Soil Formation

Objectives• Identify five factors involved in soil formation.

• Describe different types of parent material.

• Explain topography and how it affects soil formation.

• Explain how organisms affect soil development.

• Describe how time and weathering affect properties of soil.

• Explain how climate affects the development of soil.

Soil Formation

•Five factors in forming soil

•Parent Material

•Topography

•Organisms

•Time/weathering

•Climate

Parent Materials

•Classified by the way they were moved and scattered.

Parent Materials

• Moved by glaciers

• Glacial Till - No layers

• Can contain fine soil to pebbles to boulders

• Loess - occurred from blowing of soil after glaciers melted and dried

• Most Desirable

• Outwash - occurs during melting; larger items deposited first, smaller items deposited last

Parent Materials

•Deposited by flooding streams and rivers

•Alluvium - Bottomlands and flood planes

Parent Materials•Bedrock - Shale,

Sandstone, or Limestone

•Organic Matter - Usually swamp vegetation that has accumulated

•Known as Peat and Muck (muck is more decomposed than peat)

Topography

•Steepness(degree), length, shape, direction

•Nearly level soils are generally poorly drained

•Moderate to steep slopes are generally well drained

Time / Weathering•Physical Weathering

•Temperature, Water, Wind,

•Freeze/Thaw

•Chemical Weathering

•Rainwater is mildly acidic

•Oxidation

Climate•Rainfall - slowly by surely erodes

•Wind wears away at rock

•Hot Summer/cold Winter - Freeze/Thaw

•Humid area - more leaching than dry areas

Organisms•Plants, Insects, Organisms

•Greatest affect on soil formation is the plants that once grew in it

•Native Vegetation

•Example: common native vegetation in the Midwest.

•Tall Prairie Grass

•Prairie Soils

•Deciduous-hardwood forests

•Timber Forests

•How is the Midwest different from Northern Utah?

Organisms