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Soils

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Soils Earth s Changing Surface Review Weathering breaks down rock Mechanical Chemical Erosion removes the rock particles What is soil? – PowerPoint PPT presentation

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Title: Soils


1
Soils
  • Earths Changing Surface

2
Review
  • Weathering breaks down rock
  • Mechanical
  • Chemical
  • Erosion removes the rock particles

3
What is soil?
  • The loose, weathered material on Earths surface
    in which plants can grow.

4
Soil
  • Bedrock - the solid layers of rock beneath soil.

5
Soil Composition
  • Mixture of rock particles, minerals, decayed
    organic material, water, and air
  • Humus decayed organic material in soil

6
Soil
  • Fertility of Soil measures how well the soil
    supports plan growth.
  • Rich in humus has high fertility
  • Why does fertility of soil matter?

7
Soil Texture
  • What does soil feel like?
  • Sand feels coarse and grainy
  • Clay feels smooth and silky
  • Soil texture depends on the size of soil
    particles.

8
Soil Particle size
Clay Silt Sand Gravel
Less than 1/256 mm Less than 1/16 mm Less than 2 mm 2 mm and larger
9
Loam
  • Soil that is made up of about equal parts of
    clay, sand, and silt is called loam.

10
Soil Formation
  • Forms as rock is broken down by weathering and
    mixes with other materials on the surface.

11
Soil Formation
  • Soil Horizons
  • A layer of soil that differs in color and texture
    from the layers above or below it.

12
Soil Horizons
13
A Horizon
  • Topsoil a crumbly, dark brown soil that is a
    mixture of humus, clay, and other minerals.
  • Develops as plants add organic material to soil
    and plants weather rock.

14
B Horizon
  • Subsoil clay and other particles washed down
    from the A horizon, but little humus.

15
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16
Soil Types
  • Thousands of different types of soil in U.S.
    alone
  • Classified based on climate, plants, and soil
    composition.

17
Living Organisms in Soil
  • Some soil organisms make humus
  • Some soil organisms mix the soil and make spaces
    in it for air and water.
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