Soil Erosion Flashcards Preview

IPNI Soil and Water Management > Soil Erosion > Flashcards

Flashcards in Soil Erosion Deck (18):
1

Types of Erosion

  • sheet - thin layer of soil removed by running water
  • rill - small channels formed by running water
  • Gully - large channels 
  • Surface Creep
    • slow movement of soil down a slope
    • accelerated by saturated conditions, freezing, thawing
  • Saltation
    • wind causes small soil particles to move on surface in bouncing fashion 
  • Suspension
    • wind carries fine soil particles, fly above the soil surface
  • Tillage Erosion
    • moves soil from top to bottom of a field creating shallower soils at the top of field and deeper at the bottom

2

How following affects rate of Erosion by Wind

 

  • Soil surface roughness decreases erosion
  • use wind blocks
  • Unsheltered distance - as unsheltered distance increases, erosion increases
  • Soil texture
    • sand erosion moving by saltation can dislodge silt and clay particles contributing to erosion

3

Erosion impact on

Crop Yield Potential

  • primary influence is change in properties of the root zone with erosion
    • topsoil is highest in
      • organic matter,
      • nutrients and
      • biological activity
      • good physical properties
    • Erosion decreases topsoil depth
      • crop yield potential declines

4

Erosion impact on

Water Holding Capacity

  • loss of topsoil can reduce water holding capacity of a soil
    • and cause reduced plant avail water
  • changes in texture as subsoils are exposed 
    • could reduce / increase water holding capacity depending on texture

5

Erosion impact on

Nutrient Content

  • Nutrient content will generally decline with erosion
    • loss of organic matter (source of NPS)
      •  typically retained near surface of soil

6

Erosion impact on

Infiltration

  • Erosion will often reduce soils infiltration capacity
    • exposed soils typically have less organic matter and more clay

7

Erosion impact on

Water Quality

  • Water quality of recieving streams, lakes, reseviors impaired from sediment load during erosion
    • sediment carries nutrients (NPS) that can cause
    • eutrophication 
      • excessive aquatic growth - weeds, algae
    • light penetration declines

8

Erosion impact on

Air Quality

  • suspension wind erosion can fill air with particulates that reduce air quality

9

Strip cropping

  • soil detachment reduced
    • cropped soil is protected
    • slope length of uncropped soil reduced
  • Soil Transport reduced
    • cropped strips have increased infiltration and retain sediment

10

Contouring

  • soil detachment reduced
    • slope is reduced when runoff moves along contours 
      • means lower water velocity
  • Soil Transport reduced
    • slope is reduced when runoff moves along contours
      • sediment can settle out 

11

Terraces

  • Soil detachment reduced
    • reduced slope
    • increased infiltration
  • Soil Transport Reduced
    • reduced slope
    • often cropped increasing sedimentatio

12

Grassed Waterways

  • Soil Detachment reduced
    • main channel for water is protected from erosion by sod
  • Soil Transport reduced
    • slowed velocity through sod

13

Row Spacing and Direction

  • Soil Detachment reduced
    • narrower rows allow earlier vegetation cover
      • protects surface from wind / rain
    • rows with slight slope / contour increases infiltration
  • Soil Transport reduced
    • narrower rows increase soil roughness
    • slight slope along contour reduced amount of runoff

14

Strip Cropping 

  • commonly used to reduce erosion of one crop (corn) with a second crop (forage)

15

Terraces

  • Terraces are used where slopes are too steep to allow strip cropping or contouring

16

Grassed waterways 

  • used to prevent gully erosion in areas where surface water concentrated

17

Surface Residues

  • are used in the portion of the year when soil is not cropped

18

Cover crops

  • used to protect bare soil 
    • reduces nitrate leaching
    • fixing atmospheric N (legumes)
    • improving soil tilth