Today: whats up with soil

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Today whats up with soil?
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Today whats up with soil?

• Human uses of soil
• food, medicine, beer, wine, livestock
• biotechnology - antibiotics
• culture - art, shelter, archaeology
• your nose? The smell of rain is from spores
• Soil in my yard
• gardening, grass, compost bin

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Earths environmental spheres 
REVIEW

• Atmosphere gaseous envelope surrounding Earth
  (e.g., nitrogen, oxygen, argon, water vapor)
• Hydrosphere all forms of water (oceans, ice,
  fresh)
• Lithosphere inorganic solid rocks minerals
• Biosphere where living organisms reside (at/near
  surface)

Atmosphere? Hydrosphere? Lithosphere? Biosphere
?
Where are they?
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Soil

• The area between the atmosphere and bedrock is
  called the REGOLITH
• regolith includes an unconsolidated mix of
  soil, sediments, and weathered rock

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Soil

• Soil is born from the physical and chemical
  disintegration of rock, or the WEATHERING of rock

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Soil
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Soil

• weathering vs. erosion

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Soil

• The surface of the lithosphere is usually, but
  not always, covered with soil

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no soil
Soil
no soil
no soil
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Soil

• How does soil form?
• Five factors
• Geology
• Climate
• Topography
• Biology
• Time

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Soil forming factor 1 Geology
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Soil forming factor 2 Climate

• Chemical and biological processes are accelerated
  in warm, moist climates and slowed in cold, dry
  climates.
• Surface water and water in soil carries chemicals
  in solution and tiny particles in suspension.

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Soil forming factor 3 Topography

• Slope and
• drainage
• influence
• soil character-
• istics. Generally,
• deeper soils on
• flatter surfaces.

N
N
N
S
S
S
N
S
N
S
N
S
N
north to left
S
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Soil forming factor 4 Biology

• Living and dead plants and animals
• Roots, worms, ants, prairie dogs, termites,
  grubs,
• In some places, worms deposit 25 tons of casts
  per acre.
• ¾ of soils metabolic activity is generated by
  microorganisms (microbes). Microbes release
  nutrients from dead organisms.

http//www.urbanext.uiuc.edu/worms/live/
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Soil forming factor 5 Time

• We are talking geologic slowness here!
• Older soils generally display more horizons (or
  layers).

SUPER OLD
OLDER
YOUNGER
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Soil components

• Inorganics (minerals)
• Air
• Water
• Organics

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Soil components

• Inorganics (50 of volume)
• sand and silt from weathered rock
• mostly quartz (SiO2)
• some feldspars and micas
• clay
• smaller than sand/silt
• colloidal in size (too small to see)
• form plateletes or sheets
• water moves freely through clay
• negatively charged, attract cations
• many plant nutrients are cations!

feldspars in granite weather into clay
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Soil components

• Air (25 of volume)
• generally found in voids lined with water
• saturated (100 humidity)
• rich in carbon dioxide (CO2), poor in oxygen
• plant roots remove the O and respire the CO2.
• CO2 slowly seeps into atmosphere

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Soil components

• Water (25 of volume)
• from rainfall, snowmelt
• water moves down AND up AND laterally
• envelops soil particles

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Soil components

• Water (25 of volume)
• Four forms of soil moisture
• Gravitational water (stays only a short time)
• performs eluviation and illuviation
• helps keep top layers open and coarse and bottom
  layers compact and dense
• Capillary water (plants use this)
• sticks around from surface tension (ST)
• ST is a force stronger than the downward pull of
  gravity

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Soil components

• Water (25 of volume)
• Four forms of soil moisture
• Hygroscopic Water (unavailable to plants)
• a microscopically thin film of water
• bound very tightly to all soil particles
• Combined water (entirely unavailable)
• held in combination to minerals
• freed only if chemicals are altered

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eluvial zone (eluviation) water carrying fine
particles down
illuvial zone (illuviation) the deposition of
these fine particles
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Soil components

• Review of all four forms of soil moisture

from your book, pg. 361
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Soil components

• Soil-water budget (balance)
• water added (precipitation)
• water removed (evaporation)
• when there is SUPPLUS water, the soil is at field
  capacity. When moisture is DEPLTED, soil reaches
  wilting point.

determined by temp. and humidity
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Soil properties
(field capacity)
(field capacity)
time --gt
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Soil horizons

• O horizon live and decaying organic matter
  litter from dead plants/animals common in
  forests uncommon in grasslands some soils do
  not have an O horizon

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Soil horizons

• A horizon the topsoil layer a blend of
  minerals and organics sometimes at surface
  coarse due to eluviation horizon in which seeds
  germinate.

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Soil horizons

• E horizon normally lighter in color an eluvial
  layer from which clay, iron, and aluminum have
  been removed a concentration of sand and silt.

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Soil horizons

• B horizon the subsoil layer a mineral horizon
  of illuviation where most minerals from above are
  deposited a collection zone for clay, iron, and
  aluminum very dense and clay rich.

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Soil horizons

• C horizon loose regolith roots cant quite make
  it down this far very little if any organics
  mostly fractured bedrock.

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Soil horizons

• R horizon mostly unweathered, solid bedrock.