"There can be no life without soil

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"There can be no life without soil and no soil
without life"  Charles Kellogg (of Corn Flakes
fame) "The nation that destroys its soil
destroys itself"  Franklin Roosevelt (in the
wake of the Dust Bowl events) "Dirt's a lot more
fun when you add water"  Dennis the Menace
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• Why ecosystem ecologists need to
• understand soils
• Provide nutrients for building living
• tissues

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• Why ecosystem ecologists need to
• understand soils
• Provide nutrients for building living
• tissues
• b) Function as water storage components

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• Why ecosystem ecologists need to
• understand soils
• Provide nutrients for building living
• tissues
• b) Function as water storage components
• c) Function as a major carbon storage
• component

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Soils and Ecosystems are organized by five
Independent variables (from chpt 1 of
text) Climate Organisms Topography or
Relief Parent material Time to develop Hans
Jenny called his five state factors The
cl,o,r,p,t concept.
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• From Friday
• Effect of climate on parent materials

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• Important Equation (WEATHERING)
• OFTEN
• Parent Material acid secondary minerals
• plant nutrients
• b) Secondary minerals acid other minerals
• plant nutrients
• SOMETIMES
• Rock acid dissolved materials which are
• 1) toxic to plants or 2) simply leached away.

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Sand Silt Clay
P
Parent Material
weathering
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Parent Material
physical weathering (disintegration)
Sand (0.05-2 mm) Silt (0.002-0.05 mm) Clay
(lt0.002mm)
(text, pg 61)
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Fig. 3.12 texture gives a soil a name, e.g.
loam
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Texture varies greatly across the Great
Plains (and sometimes exhibits political
boundaries?)
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Going back to weathering through time The type
of clays in the soil have a HUGE effect on the
ability of the soil to provide nutrients to
plants. Clays function as temporary nutrient
holding sites better known as CATION EXCHANGE
SITES (soils have CEC rankings cation
exchange capacities that vary 30 fold in the
U.S. alone.)
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For many types of parent material THE
WEATHERING FORMULA BECOMES (IGNORE THE ACID AND
NUTRIENTS FOR NOW)
Rock --gt 21 clays --gt11 clays --gt
Aluminum and iron oxides

--gtDissolved.
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Whats in your planet?
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weathering
21 clays
Rock (PM)

• Weak bonds between units
• allow for expansion
• create high internal surface area for exchange of
  H2O cations
• Si4 gets replaced by Al3 ? crystal now
  negatively-charged

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weathering
stronger linkages ? nonexpanding space ? less
substitution of cations ? less total negative
charge (CEC)
21 clays
11 clays
CEC21 clays gt CEC11 clays
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11 clays
hot, wet weathering
cold, wet weathering
silicon oxides others
Fe and Al oxides
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Fig 3.10
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• Recallthe weathering process uses acid,
• and most of that acid comes from.
• The atmosphere
• Soil chemical reactions (biota not involved)
• Biota-derived source for reaction
• Disassociation of the water molecule.

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Carbonic acid is produced from respiration by
plants, animals and microbes into moist soil.
The biota also contribute to soils by adding
organic matter. Climate parent material
biota time a soil with unique physical
characteristics.
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Soils develop layers (see figure on hidden web
page)
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Soils develop layers One or more of the layers
can be absent under different
conditions. Leaching of substrates by water
(and the stuff water carrieslike H, dissolved
organics, etc) is the major player.
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Ancient soilonly an E horizon present.
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What do plants need from the soil? CHOPKNS CaFe
MgMn BClCuMo All but CHO and sometimes N are
obtained from the soil While Nitrogen is
strongly biologically mediated and provided by
atmospheric sources, Phosphorus is strongly
mediated by abiotic soil processes.