Soil Abiotic

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Soil - Abiotic

• Why is it important?
• It is one of earths greatest natural resources.
• Almost all of the worlds food crops grow in
  soil.
• The worlds livestock eat plants that grow in
  soil.
• Most building foundations are put into soil.

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What is it?

• Pieces of rock, mineral and
• decaying material

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How is it made?

• Breaking up of pieces of rocks and minerals
  through mechanical and chemical weathering.

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• Mechanical Weathering
• 1. Frost Wedging
• Bedrock breaks up due to freezing, thawing, and
  erosion.

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2. Gravity Land or rocks move downhill, collide
and break into smaller pieces.
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3. Wind or water abrasion
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4. Plant Exfoliation - break up rocks
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Chemical Weathering

• 1. Oxidation oxygen combines with water and
  minerals in the water.

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2. Carbonation - When carbon dioxide dissolves in
water, carbonic acid is formed. This acid reacts
with other substances, creating a chemical change.
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How long does it take?

• It can take hundreds of years to form a few
  centimeters of soil.

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What are two of the most important functions of
soil

• Provides a means for plants to get nutrients and
  water.
• Provides support for plants.

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What are soil layers in the Earth? (not in
biosphere)

• Litter top layer of decaying leaves and grass
  this layer is rich in nutrients.
• Top Soil a mix of rock fragments, nutrients,
  water, air, critters, and decaying material
• Sub Soil rock fragments, water and air this
  layer has less decaying material
• Bedrock this layer is just rock

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• Leaf Litter
• layer of leaves on the ground
• provides habitat and nutrients
• Loam
• Typical soil mixture
• 20 clay,
• 40 sand,
• 40 silt

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Soil Characteristics

• Texture the size of the particle
• Clay- smooth, sticky when wet, smallest particle,
  forms clods when hard, stays suspended in water
  the longest
• Silt- smooth, but not sticky
• Sand Largest particles gritty
• Humus various sizes, rich in nutrients, layer
  of decaying materials

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Soil Characteristics (continued)

• 2. Color Affected by water drainage, amount of
  decaying material and bedrock
• Black rich in nutrients and humus
• Gray poor water drainage and air flow

3. Water Held Small particles hold more water
too little water and plants will dry out quickly
too much water, air will not flow properly and
roots will rot
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Soil Characteristics (continued)

• 4. Percolation Rate
• how fast a certain amount of water (mL or L) can
  flow through a substance
• Larger particles allow water to flow through
  the fastest
• In a water table, water fills the spaces between
  particles in the soil.

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Soil Characteristics (continued)

• 5. Nutrients most nutrients come from the humus
  layer
• Nitrogen (N) good plant color and growth
• Phosphorus (P) healthy roots and blooms
• Potassium (K) hardy plants with strong stems

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Soil Organisms

• Different soils have different types and
  numbers of organisms. For example in pounds per
  acre you would find

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• Decomposers
• These organisms are important part of the food
  chain. They help to recycle nutrients.
• Sterilized potting or top soil has no organisms
  in it.