WaterCaused Soil Erosion

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Water-Caused Soil Erosion

• This presentation is from Virginia Tech and has
  not been edited by the Georgia Curriculum Office

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Objectives

• Explain how land capability classes relate to
  wise soil use
• Describe main vegetative methods used to control
  water caused soil erosion
• Describe main mechanical methods used to control
  erosion
• Design proper control strategies

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Land Capability Classes

• Range from Class I to Class VIII
• Classes IIV are suitable for row crop production
  
• Class I is the best. Nearly flat with little
  erosion
• Class IV has moderate slopes and is prone to high
  levels of erosion
• Should be covered with vegetation continuously

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Class I
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Class III
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Classes V VI

• Class V is very nearly level but it may be too
  wet or rocky for crop production
• Class VI is very rocky and steep with very
  shallow topsoil
• Good for permanent grazing and forests
• Overgrazing should be avoided

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Class VI
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Classes VII VIII

• Almost impassible
• Limited grazing and forest production
• Class VIII is not suitable for any farming

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Class VIII
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Class exercise

• classify the land in the following pictures

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Control Measures

• Vegetative
• Mechanical

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Vegetative Control

• Cover crops
• Crop rotation
• Strip cropping
• Grassed waterways

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Cover Crops

• Close growing crop grown on the field when the
  cash crop isnt growing
• Winter wheat, rye, vetch, etc
• Reduce erosion, improve soils organic matter, and
  improve soil tilth (workability)

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Crop Rotation

• Orderly and repeated sequence of different crops
  grown on the same field
• Example 3year rotation using corn, soybeans,
  wheat
• Advantages
• Soil tilth is better
• Improves water absorption
• Reduces erosion
• Increases organic matter
• Improves moisture storing capacity

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Strip Cropping

• Alternating bands of different crops
• Laid out on the contour or across a prevailing
  slope
• Hay strip, corn strip, hay strip
• Hay strips increase water absorption, holds the
  soil in place, reduces gullying, slows down
  running water

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Grassed Waterways

• Natural drainageway permanently covered by
  vegetation
• Used widely to prevent gullying in natural draws
• Types
• Trapezoidal
• Vbottomed
• Saucermost common
• Perrenial grasses such as fescue or bluegrass are
  typically used
• Quickly establish sod (overseed, fertilize, mulch)

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Mechanical Control

• Conservation Tillage
• Contour Farming
• Terraces
• Fencing

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Conservation Tillage

• Tillage system that is economically practical for
  crop production and aids in soil and water
  conservation
• Crop residue from previous crop helps protect
  soil
• Common methods include minimum till, no till
  stubble plant and strip tilling
• Advantages
• Less energy and time are require
• Soil moisture levels increase w/ increase in soil
  organic-matter levels
• Reduces soil erosion

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• Disadvantages
• Increase in weed, insect, and disease problems
• Crop residue ties up nitrogen thus requiring more
  fertilization

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Contour Farming

• Plowing around the hill instead of up and down it
  
• Prevents runoff from moving straight down the
  hill

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Terraces

• Larger surface channels constructed on a contour
  with a controlled rate of fall
• Terraces are needed if slope exceeds about 2
• Should be designed by Soil Conservation Service
• Example waterbreaks in old logging road

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Fencing

• Fencing cattle away from creeks and ponds
• Greatly reduce creek bank erosion
• Reduces cattle waste from directly entering the
  water source

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Developing Control Strategies
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A logging crew is moving to this area. The crew
plans to clearcut the forest. What suggestions
can you provide the crew to minimize soil
erosion.