Soils

1
Soils

• An Important Resource

2
Soil or Dirt?

• Soil is not just dirt that we should clean up or
  get rid of, rather it is an important part of our
  daily lives.
• Soil is a combination of old rock and organic
  material (decomposing plants and animals).

3
Soil Types

• Igneous
• Hardened molten rock
• Sedimentary
• Rock from the sea bottom
• Metamorphic
• Rock that comes from pre-existing rock created
  by heat and pressure

4
Soil Development

• Soil develops from the parent material.
• In PA the parent material is weathered bedrock.
  (No not from the flintstones, but hard old rock
  found underground!)
• In places where the soil is more soft, the parent
  material might be from loose gravel or decaying
  organisms.

5
Soil Changes

• The landscape of the Earth is always changing.
  Throughout geologic time, the soil in PA has
  undergone many changes.
• Changes include
• Climate
• Erosion by water, wind, or ice
• Plant growth
• Chemical reactions within soil

6
Soil Organisms

• In one teaspoon of soil there can be hundreds of
  millions of soil organisms.
• Organisms stay close to the surface and give soil
  its structure and fertility.
• Organisms include snails, termites, earthworms,
  centipedes, beetles, slugs, fungi, ants, and
  mites.

7
Soil Textures

• Sand
• Size between
• 2 mm and 0.05 mm
• Soil contains gt84 sand
• Silt
• Size between 0.05 mm and 0.002 mm
• Soil contains gt80 silt and lt12 clay
• Clay
• Size less than 0.002 mm
• Soil contains gt45 clay, less than 40 silt and lt
  45 sand

8
Soil Layers

• Layers are called Horizons.
• Horizons occur naturally and are distinguished by
  color, texture and amount of organic material.
• O Horizon - surface litter
• A Horizon - topsoil
• B Horizon - subsoil
• C Horizon - Parent Material
• R Horizon - Bedrock

9
Pennsylvania Soils

• The Soil Conservation Service of the US
  Department of Agriculture surveys and maps the
  soil and publishes their reports.
• Soil surveys contain information about crop
  growing, building, and soil features.
• Each county in PA has a completed soil survey.
  Complete the soil survey activity to determine
  the soil type in lebanon county.