Soil Erosion

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Soil Erosion
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Bird City, Kansas
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St. Francis, Kansas
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San Luis Valley, Colorado
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Al Asad, Iraq
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The Dustbowl
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How much soil is lost?

• 5 Billion Tons, Billion with a B lost each year
• 3.5 Billion tons due to Water
• 1.5 Billion tons due to Wind

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What is average loss?

• Scientists expect to lose 5 tons per acre per
  year
• This much can be re-captured through soil
  formation
• Water makes up 4.8 tons lost
• Wind makes up 3.3 tons lost
• 8.1 tons is average
• THIS IS TOO MUCH!

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Lasting effects of erosion

• Loss of topsoil-loss of productive organisms
• Organic matter gone along with N-P-K
• Reduced Root Zone-less water holding capacity
• Gullies make farming difficult
• Pollutes lakes, streams causing harm to wildlife
• Sediment fills up lakes, streams, and waterways
• Loss of due to un-productive soil

Sediment fills and pollutes a lake
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What affects erosion

• 1 Texture and Structure
• The coarser the texture, the higher infiltration
  rate, the lower amounts of run-off
• Fine particles detach easier than large particles
• Silt erodes faster than sand
• Good structures resist rain splash and wind lift

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What affects erosion

• 2 Slope
• Length and steepness or grade both need
  considered
• Length accounts for volume of erosion
• Grade creates water velocity
• Long fields have snowball effect with wind
• Little loss at the head end, piles of soil at the
  bottom end

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What affects erosion

• 3 Surface Roughness
• Rough soil slows water
• and reduces downhill flow
• Tillage ridges are helpful
• Tillage across slope prevents erosion, tillage
  with the slope promotes erosion

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What affects erosion

• 4 Surface Cover
• Surface cover reduces impact from falling water
  and slows down movement of water
• Surface crops roots hold soil closely
• Row crops need a foliage canopy to help protect
  soil

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What affects erosion

• 5 Climate
• Dry soils and dry climates promote wind erosion
• The drier the soil particles the greater risk of
  being picked up and moved elsewhere
• Dry weather promotes wind loss

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Types of erosion

• 1 Splash Erosion
• Water hits the soil and can move particles as
  much as 5 feet!

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Types of erosion

• 2 Sheet erosion
• A thin layer of soil is removed as a sheet.
• Sheet erosion hides until topsoil is lost and
  subsoil is exposed.

Sheet erosion exposes sub-soil in the circles
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Types of erosion

• 3 Rill erosion
• Many small channels on slopes
• Running water carves out rills
• Still can be filled in by tillage

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Types of erosion

• 4 Ephemeral (e fem er al)
• Large rills
• Tillage wont completely fill them in
• The next rain will create gullies if not fixed

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Types of erosion

• 5 Gully erosion
• So large equipment cannot cross
• Begin on steep slopes where water creates enough
  energy to cut large channels in the earth