uwuw c. henry soil basics! the excited skin of the earth! physical components chemical processes...
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UWC. Henry
Soil basics!
The excited skin of the earth!
•Physical components•Chemical processes•Biological processes
Chuck Henry
UWC. Henry
Ecological Restoration HandbookBy: Chuck Henry & Elena Olsen
Chapter 2 from:
UWC. Henry
Proportions of the physical parts of soil
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Relative sizes of the three mineral soil particles
Gravels and rocks (mineral particles > 2 mm do not count as soil to a soil scientist! They just take up space!
UWC. Henry
Sand
• Relatively big and not very reactive
• Water passes through sand quickly
• Doesn’t hold on to nutrients very well
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Silt
• In size, between clay and sand
• Can hold some water, can hold some nutrients
• Can erode!
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Clay
• Almost the opposite of sand
• Very small
• Holds water very tightly
• Very sticky!
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Mixtures of particles• If you have just the right amount of each
type or soil particle– the best characteristics of each one blend
to make a really good soil
• Best soils:– loams
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“the fuel that runs the soils engine!”
And then… organic matter!
• Holds and also releases water
• Holds and also releases nutrients
• Energy for healthy microbial populations
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The other half of soil: pore space!
air
water
• Where water and air is held
• Where roots grow
• Macropores– Water drains
• Micropores– Hold water
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Soil forms in layers called horizons
All the soil horizons make a soil profile
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Soil forming factors make soil the way it is
• Parent material– The original mineral particles
• Time– How long processes have been working
• Climate– Precipitation and rainfall
• Biota– Plants and animals living on the soil
• Topography– Slope, depressions, ridges, etc.
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Local soils around Western Washington
• Till
• Outwash
• Lacustrine
• Alluvial
• Organic/mucK
• Residual
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Till
• Ablation till– Loose, unsorted
over
• Basal till– Highly compacted
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Outwash
• Coarse material
• Left from water rushing off glaciers
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Lacustrine
• Clay deposited in lakes
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Alluvial
• Particles sorted by rivers
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Organic/muck
• Forms in bogs
• Dead plant parts
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Residual
• Decomposed rock– Volcanic– Sedimentary– Metamorphic
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