Soil Types

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Soil Types
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Quick Review

• 1. What is the process that forms soil?
• - weathering
• 2. What are the two types of weathering? What
  causes them?
• - physical (rain, snow sleet, hail)
• - chemical (acids)
• 3. What is another name for a layer of soil?
• - horizon

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More Review!

• 4. What is the name for soil that has a lot of
  decaying organic material?
• - humus
• 5. Which layer is most important for plant
  growth?
• - topsoil
• 6. What is the main cause of desertification?
• - improper management of soil which leads to
  erosion.

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Types of Soils

• Soil is classified according to the type of
  mineral base and the size of the particles.
• There are 3 types

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1. Sand

• Very large particles
• Feels rough
• Does not hold water or nutrients well.

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2. Silt

• Particles are smaller than those in sand
• Feels smooth and powdery

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3. Clay

• Has very small particles, and gums together.
• It holds water and nutrients well, but plants
  roots cant grow well.
• While it holds water well, it takes a long time
  for water to permeate a clay soil.
• Brief, heavy rains may not reach plant roots.

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Loam

• Mixture of sand, silt, and clay and organic
  matter.
• Water and nutrient holding abilities vary with
  composition.

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Which type is best?

• The ideal type of soil for plant (crop) growth is
  partway between these two extremes.
• Loamy soil has neither too small nor too large
  particles (Its just right!)
• Loamy soil has a good percentage of decayed plant
  material or humus which provide the nutrients
  that plants need.

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Further Resources

• National Resources Conservation Service website.
  Try out the Web Soil Survey tool to see whats
  under your feet
• US Environmental Protection Agency
• Digging to China?
• Introduction to Soils