Soils

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Soils Biology
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Soil
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Soil isnt dirt, but the accumulation of decayed
material over time
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Soil is a Fundamental Part of the Ecosystem
The living systems above and below the ground are
based on the properties of the soil.
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The Study of Soil is called Pedology
Soila natural body of solids, liquid, gases,
with horizons (layers) the ability to support
plants
color texture structure roots pores other features
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Composition of Soil by Volume

• Ideal Fertile Soil
• Water 25
• Air 25

• Ideal Fertile Soil
• Mineral 45
• Organic Matter 5

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Classification Systems Of Soil

• Texture Criterion diameter of soil particles

Soil Texture gravel gt2 mm
sand 0.052 mm
silt 0.0020.05 mm
clay lt 0.002 mm
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Soils Perform Several Vital Functions
Sustaining plant and animal life below and above
the surface
Regulating and partitioning water and solute flow
Filtering, buffering, degrading, immobilizing,
and detoxifying
Storing and cycling nutrients
Providing support to structures
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Soils Also Have Scientific Names

• Like plants and animals, soils are classified
• The system is called Soil Taxonomy
• The highest level is the soil order (12)
• The lowest level is the soil series, often a
  place name

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Soil Studies Include Other Fields
Science ecology, biology, chemistry Social
Studies world trade, land use Mathematics soil
loss over one hectare History US settlement,
dust bowl Art soil crayons, acrylic paints
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Soil Assessment is Also Important to Minimize Risk
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Soils Are Alive
Organism Types bacteria fungi protozoa nematodes a
rthropods earthworms
Roles Benefits decomposition release
nutrients create pores stabilize soils
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Organic Matter

• microorganism
• soil animal
• organic manure

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Soil pH Value
The best pH value for plants is 6.5

• climate high temperatures and humidity change pH
• microorganisms bacteria
• environment acid rain

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Soil Tests for Quality physical, chemical,
biological
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Physical Tests - Soil Density Texture

• Fill a graduated cylinder with ¾ water
• Add 2-3 teaspoons of soil.
• Shake well.
• Allow to settle, and measure the relative
  percentages of each level - look at particle size
  differences sand, silt, and clay layers.

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Permeability

• Assemble filter paper, funnel, and beaker.
• Add two teaspoons of dry soil.
• A 25-50 ml of water start timer.
• Record time elapsed when water stops dripping

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Other Laboratory Tests Include Checks For Soil
Nutrients (N, P, K) and pH.

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Most kits based on simple extraction methods,
combined with color charts for interpretation.
pH
Nitrogen (NO3)
Phosphorus
Potassium
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All Right, Lets Play in the Dirt!