Soils

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Soils
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Soils

• Soil is the loose covering of broken rock
  particles and decaying organic matter
• Soil is the end result of physical and chemical
  weathering.
• Soil forms as rock is broken down be weathering
  and mixes with other material on the surface.
• The longer a soil has been forming, the thicker
  it is.
• Climate has a great affect on soil formation.
  Temperature and precipitation play an important
  role.

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How is soil created?

• Decaying organic matter is called humus.
• It is often leaf litter that is broken down by
  decomposers.
• Ex. Are ants, worms, etc.

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Soil Formation

• During its development, soil forms in layers
  vertically.
• Solid bedrock from which weathered pieces of rock
  first break off is known as the parent rock.
• The weathered material then rests on top of the
  parent rock.

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Residual vs. Transported

• Residual soil is soil that comes from the bedrock
  that it sits upon.
• A transported soil is soil that has been moved
  from a different location

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Soil Profile

• A soil profile is a vertical sequence of soil
  layers.
• A distinct layer is called a soil horizon
• The three major layers are A, B, C

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Soil Horizons

• A Horizon- Topsoil- Soil rich in humus and
  usually dark colored
• B Horizon- Subsoil-Rich in clay minerals
• C Horizon- Weathered bedrock (parent rock).

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Texture

• Size of soil particles is soil texture.
• Particles are classified according to size.
• In order from largest to smallest they are
• Gravel
• Sand is the largest .05- 2 mm
• Silt is the middle .0002 - .05 mm
• Clay is smallest gt.002 mm

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Fertility and Color

• Soil Fertility is the measure of how well a soil
  can support plant growth.
• A soilscomposition and climate are main factors
  in determining its color.
• Red/Yellow Fe oxidation
• Dark Colored Humus
• Gray/Blue low O2

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Loam

• A loam is a soil that is equal parts of clay,
  sand and silt.
• It is the best for growing plants!

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Soil Types

• Climactic conditions are the main influences on
  soil development.
• Polar Soil
• Temperate Soil
• Desert Soil
• Tropical Soil