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SOIL CONSERVATION

Learning Plan 14

Intro to Soil Science

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EROSION

Natural erosion

Human-induced erosion

Erosion-control practices

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COSTS OF EROSION

Production losses

    • Farmer and consumer

Pollution and sedimentation

    • Public

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WATER EROSION

  • Erodes more soil than the wind
  • The process of water erosion

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WATER EROSION

  • Rainfall erosivity
    • Volume: total rainfall in a rainfall event
    • Intensity: how fast rain falls
  • Texture and structure
    • Affects infiltration rate
    • Particle size affects detachment
  • Slope
    • Length
    • Grade

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WATER EROSION

  • Surface roughness
    • Rough soil impedes downhill water flow
      • However, erosion can be worse if water collects behind ridges and they break
  • Soil cover
    • Mulch and cover crops reduce erosion
    • Row crops and nursery stock intercept rainfall and can reduce erosion

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PREDICTING SOIL LOSS

  • Revised Universal Soil Loss Equation 2

A = R K LS C P

    • A: Tons of soil lost per acre each year
    • R: Rainfall and runoff factor
    • K: Soil erodibility factor
    • LS: Slope factor
    • C: Cover and management factor
    • P: Support practice factor
  • Revised: refined factor values

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CONTROLLING WATER EROSION

    • Reduce raindrop impact and soil detachment
    • Reduce or slow runoff
    • Remove excess water
    • Filter soil particles from running water

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WIND EROSION

    • Larger soil particles extend past the boundary layer and are moved when wind reaches 10 to 13 mph

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WIND EROSION

Effects

Factors

Wind Erosion Equation

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CRITICAL PERIODS FOR WIND EROSION

When the soil is fallowed

Between harvest and following crop cover

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TILLAGE EROSION

  • Redistribution of soil through action of tillage and gravity
  • Results in progressive down-slope movement of soil

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EFFECTS OF TILLAGE EROSION

Impacts crop development and yield

Change in soil structure increases erodibility

May move subsoil which can bury topsoil

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EROSION AND CLIMATE CHANGE

    • Response to mid-twentieth century conditions

Current erosion technologies

    • Likely to increase

Highly erosive rainfall

    • May become unreliable

RUSLE

    • May increase

Wind and dryness

    • Adjustments to will be needed

Agricultural practices

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SUMMARY

This chapter reviewed several topics

Water and wind erosion

Water causes about three-fifths of total erosion losses

Soil loss computing

RUSLE2

Erosion control practices

Contour tillage, contour strip cropping, etc.

Climate change

Will likely challenge efforts to predict and control erosion

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