Threats to Soil

1

• Threats to Soil

2
Threats to Soil

• Environmental or Natural Factors Temperature
• Extremes - too hot or too cold!
• Affects humus accumulation (low temps. slow the
  decay of organic matter).
• Too cold for any vegetation to grow nothing to
  die, no humus. Ex. Tundra and Polar ice caps.
• Too hot drought, with wind dust storms or
  wind erosion. Ex. deserts
• Too cold frozen ground, slow growth or short
  growing season. Again no humus! Ex. Tundra
  Polar Ice Cap.

3
Threats to Soil

• Environmental or Natural Factors Precipitation
• Extremes too wet or too dry!
• affects mineral content (rain causes minerals to
  be eluviated or leached.)
• Washing away the soil or ground.
  (Erosion)nutrients (leaching)
• Too dry less vegetation growth less
  accumulation of humus ex. Deserts
• Too wet muddy, soaked soil plants less able
  to obtain nutrients

4
Human Threats toSoilpg. 140-143

• Poor Soil Management
• Overusing the land planting the same crop ALL
  the time.
• Determine what land is BEST suited for and using
  it for that reason.
• Ex. Dont build on agricultural land. (urban
  expansion!)
• Ex. Dont grow grasses where land BEST suited for
  grapes.
• Ex. Using chemical fertilizers and pesticides.
• Ex. Leaving soil / land fallow. (NOT planting)

5
Threats toSoilpg. 140-143

• URBAN EXPANSION
• Q. Is this the BEST use of this land?
• Q. What does this land seem MORE suitable for?
• Q. What other OPTIONS do they have?

6
Threats to Soil - Desertification

• the spread of desert-like soil conditions in a
  semi-arid environment.
• Turning productive soil into unproductive, dry,
  desert-like soil!
• Occurs in hotter, drier areas and is accelerated
  by overgrazing, deforestation, leaving land fallow

7
Threats to Soil

• Erosion

• Flooding
• Overgrazing
• Deforestation

8
Reducing Soil Erosion Pg. 142

• Strip cropping
• Alternating strips of open-growing crops and
  close-growing crops.
• the close-growing crops act as a buffer or
  barrier to wind erosion.
• As well, the close-growing plants and roots
  prevent or hamper soil erosion (running water)

9
Reducing Soil Erosion Pg. 142 - Strip cropping
10
Reducing Soil Erosion

• Cover cropping
• Planting close-growing crop when NOT planting a
  harvest crop.
• Ground cover shade prevents soil from drying
  out,
• Close growing plants prevent wind erosion

• Roots prevent water erosion.
• Soak up water preventing flooding
• Increasing humus content plants get ploughed
  back into the soil returning any nutrients left
  in the plant.

11
Reducing Soil Erosion - Cover cropping
12
Reducing Soil Erosion

• Contour ploughing
• Respects the natural shape of the land.
• Crops planted perpendicular to slope of land and
  water run-off.
• Prevents soil erosion due to run-off.

13
Reducing Soil Erosion

• Terracing
• Constructing steps or shelves in the sides of
  hills or sloping land to reduce water run-off and
  retain moisture.