Teacher Information! Necessary materials: PowerPoint Guide Presentation (ppt.) Teacher Information! Necessary materials: PowerPoint Guide **all relevant terms are bolded. It is suggested that students read Ch. 4, pgs 45-50 in Managing Our Natural Resources to be prepared for this lesson and answered discussion questions 1-6 on pg 56. Teacher will need to teach from the notes in this PowerPoint in order for students to fill out all of the PowerPoint guide.

Soil Formation Pgs 46-50 in Ch.4 of Managing Our Natural Resources Slideshow adapted from Earl D. Lockridge National Soil Survey Center Lincoln, NE (http://soils.usda.gov/education/resources/k_12/tools.html) and http://aged.ces.uga.edu/Browseable_Folders/Power_Points/index.html Pgs 46-50 in Ch.4 of Managing Our Natural Resources Soil and Water Resources

Students will be able to… Presentation (ppt.) Students will be able to… Discuss how soil is formed. Describe weathering processes.

Soil Geologic definition: Loose surface of the earth as distinguished from solid bedrock (support of plant life not required). Traditional definition: Material which nourishes and supports growing plants (includes rocks, water, snow, air). Organic + Inorganic material

Soil Mixture of inorganic matter (mineral), organic matter, water, and air. Air 25% Mineral Matter 45% Water 25% Organic Matter 5%

% Soil components varies: Type of vegetation Amount of mechanical compaction Amount of soil water present.

Soil matters Inorganic matter Rock slowly broken down into small particles Organic matter Decaying plants and animals Decomposers are vital! Soil formation is slow! Soil is formed very slowly. It results from natural forces acting on the mineral and rock portions of the earth’s surface. The rock is slowly broken down to small particles resulting in soil. New soil is continually being made, but it takes a long time to create new soil and if it isn’t managed properly, soil can be eroded away more quickly than it can be made.

Parent material Minerals Rocks Examples? Aggregates of minerals Three types Igneous Sedimentary Metamorphic Parent material are the materials underneath the soil. Soil is formed from parent material. There are five major categories of parent material (minerals & rocks, glacial deposits, loess deposits, alluvial & marine deposits, organic deposits). Minerals are solid, inorganic, chemically uniform substance occurring naturally in the earth. What are some examples? Feldspar, mica, silica, iron oxides, and calcium carbonate Rocks are aggregates of minerals. (An aggregate is a mass or cluster of soil particles such as a clod, crumb or granule) Igneous rocks: lava and magma—the cooling of molten rock. Sedimentary rocks--formed by the solidification of sediment. Metamorphic rocks-–igneous or sedimentary rocks which have been reformed because of great heat or pressure.

More parent material Glacial deposits Loess deposits Common in the Midwest U.S. Loess deposits Windblown silt Eastern Mississippi Valley soils Alluvial and marine deposits Water-borne sediments Organic deposits There are five major categories of parent material. Glacial deposits: During the ice age, glaciers moved across areas of the northern hemisphere.They ground, pushed, piled, gouged, and eventually deposited great amounts of rocks, parent material, and already formed soil material. Alluvial deposits are left by moving fresh water. Marine deposits are formed on ancient ocean floors. Organic deposits are partially decayed plants that live plants are able to root and grow in. These are found in swamps and marshes.

Weathering forces Rocks & minerals break down  smaller pieces Temperature changes Water action Plant roots Ice expansion Mechanical grinding What are examples of each weathering force? Temperature changes—heating and cooling of rocks can cause rock to crack into smaller pieces. Water action--Water soluble minerals dissolve when exposed to water. Some rocks may contain some minerals that are water soluble and only that part of the rock will dissolve  caves Plant roots—Roots of plants growing in cracks in rocks can widen cracks and break rocks apart. Ice expansion—If a rock has a crack that can fill up with water, when the water expands when it freezes. This can break rock into smaller pieces. Mechanical grinding—wind blowing sand across rocks, or glaciers grinding rocks against each other. Example—rock tumbler

Organic Matter Only about 5% of most soils Small proportion but very important WHY is organic matter important? Organic matter is important: Source of plant nutrients (P, S, N) Stores soil water---plants would not grow without these two factors. Provides food energy for soil microogranisms Makes soil more tillable for farming Provides a cementing or sticky effect for the soil --Organic matter makes life possible Images from: http://extension.usu.edu/rangeplants/htm/arrowgrass, http://www.al.nrcs.usda.gov/technical/photo/crops.html, http://www.freewebs.com/worldtravle/africa.htm

Organic Matter Decayed plants and animals Two types Original tissue—still recognizable Examples? Humus—matter is too decomposed  unrecognizable WHAT causes decomposition? Examples of original tissue—twigs and leaves on forest floor Example of humus—rich brown color in soil  decomposed material As organisms die, they are attacked by microorganisms: fungi, bacteria, and others.

Review Discuss how soil is formed. Describe weathering processes. Presentation (ppt.) Review Discuss how soil is formed. Describe weathering processes.