SOIL PROFILES

Objectives•Determine what layers a

soil profile contains•Identify various types of

soil profiles•Explain the role that water

plays in the formation and movement of soil

•Create a “soil profile”•Observe how liquid travels

through the “soil profile”

What is a soil profile?•O horizon – organic

material•A horizon – topsoil•E horizon

•B horizon•C horizon – parent material

•R horizon - bedrock

Soil Layers•O Horizon – where plant

roots grow▫top layer of soil▫where animals live ▫fresh to partially

decomposed organic matters▫color varies from brown to

blackOrganic soil is produced by

the build-up of plant material and are the most productive/fertile soils.

Soil Layers•A Horizon – Topsoil

▫made of highly decomposed organic matter▫color range from brown to gray

•E Horizon – area of topsoil that has little organic material leached out▫made up of mostly sand and silt ▫lost most of its minerals and clay due to

eluviation

Soil Layers•B Horizon – where leached materials

gather▫more clay and bigger bedrock▫reddish brown or tan in color

•C Horizon – parent material▫mostly weathered bedrock▫cracked and broken surface of the bedrock

Soil Layers•R Horizon – bedrock

▫last layer in the profile▫consists of unweathered

rocks▫The process of

weathering rocks is slow and occurs over thousands of years.

Water Movement•Water is the major force responsible for

moving soil from one place to another.•Infiltration – the process of water entering

the soil•If soil is dry the water will infiltrate faster

but once the soil is wet infiltration will slow•Water is leading cause of erosion

▫Erosion is the process of soil particles being moved by water or wind.

Water Movement•Water movement is affected by three

factors▫Gravity – forces water to move downward▫Capillary action – Movement of water along

microscopic channels by two forces Adhesion Absorption

▫Soil porosity - volume of water that can be held in a soil

Create a Soil Profile•Horizon C

•Horizon B

•Horizon A

•Horizon O

Objectives•Determine what layers a

soil profile contains•Identify various types of

soil profiles•Explain the role that water

plays in the formation and movement of soil

•Create a “soil profile”•Observe how liquid travels

through the “soil profile”

Review – Identify layers of a soil profile and one distinguishing characteristic