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Soil

Soil. http:// www.youtube.com/watch?v=qajjl3esi5E (intro sent out via kmail). What is topsoil made of?. Topsoil. Soil is the topmost portion of the earth's crust; it supports life . Soil is composed of minerals and organic material.

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Soil

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  1. Soil http://www.youtube.com/watch?v=qajjl3esi5E (intro sent out via kmail)

  2. What is topsoil made of?

  3. Topsoil • Soil is the topmost portion of the earth's crust; it supports life. • Soil is composed of minerals and organic material. • Composition is based on "parent" material (in the lower crust).

  4. How Soil Forms • Residual Soil: parent material is bedrock beneath the soil • EX: • Transported Soils: soil is made from deposits left by wind, rivers and glaciers • EX:

  5. Soil Formation • How long can take to make topsoil? (see next page)

  6. SOIL FORMATION • It can take 1,000 yrs to form topsoil. • A soil forms as parent material is weathered away. • Organic material (dead plants and animals) are mixed with weathered rock)

  7. Soil composition • Every soil is a mixture of clay, silt, and sand • Clay: Very fine/small particle, tiny space between particles, dense • Silt: Too light, blown away (found in floodplains) • Sand: course, big spaces between particles

  8. Soil composition Cont’d • Perfect soil for plants is Loam • LOAM: mixture of sand (40%), silt (40%), and little clay (20%)

  9. Soil Horizons (fill in) • A Horizon: • B Horizon: • C Horizon:

  10. Stalinization of soils • Build up of salts in soil—toxic for plants (can’t take up water) • Associated with excessive irrigation of water • Problem associated with poorly drained soils (CA, Colorado River Basin) • Treatment: flush soils with lots of water • Extreme cases: salt crust too thick to be flushed

  11. Check In • 1. Which zone contains weathered parent rock? • 2. Which zone contains inorganic materials that have been washed from A horizon? • 3. Which zone contains microorganisms that breakdown material into nutrients?

  12. Soil Types • 11 major categories • What affects soils composition? (read)

  13. Soil Composition • Parent material • Plants and animals • Topography---flow of water • Climate • Heavy rains wash away nutrients • Rainfall/high temp result in high clay

  14. Soil is an ecosystem

  15. BRAINSTORM: What would happen if we lost soil? How DO we loss soil?

  16. Soil loss • Erosion: soil lost by water or wind • Chemical contamination • Salinization • Compacting by cattle hooves/machinery • 40% of cropland is degraded

  17. Stalinization of soils • Build up of salts in soil—toxic for plants (can’t take up water) • Associated with excessive water application/irriga6tion of water • Problem associated with poorly drained soils (CA, Colorado River Basin) • Treatment: flush soils with lots of water • Extreme cases: salt crust too thick to be flushed

  18. Soil Horizons • A Horizon: (topsoil)humus, inorganic particles, microorganisms decompose organic compounds into nutrients • B Horizon: (subsoil) inorganics (iron, clay, calcium) that have been washed down into the B-horizon • C Horizon: slightly weathered parent material—rock fragments • Bedrock

  19. Extension: Soil Scientists • Some things to think about: • What do scientists do? • What type of schooling do they have? • Do we need soil scientists? • http://www.youtube.com/watch?v=53pNGEO08ck&feature=related

  20. Why is soil an important resource?

  21. Soil as a Resource • Countless living organisms and numerous species live in soil • Chemical processes by these organisms enable food to grow. • Soil provides the fertility for food to grow. • Soil is a very important part of an ecosystem

  22. Questions?

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