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Soil Use and Abuse

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Soil Organisms in the soil. Soil aeration by worms and bugs ... what if we tried to feed the world as hard as we are trying to liberate Iraq? What would happen? ... – PowerPoint PPT presentation

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Title: Soil Use and Abuse


1
Soil Use and Abuse
  • Chapter 11
  • APES January 2007

2
Objectives
  • Define the roles of living organisms, physical
    forces, and other factors on creating and
    maintaining fertile soil.
  • Differentiate between the sources and effects of
    land degradation including erosion, nutrient
    depletion, waterlogging, and salinization.

3
SO what does that really mean?
  • How is soil made?
  • How is it destroyed?
  • What role are we playing as humans?

4
What is soil?
  • Soil is made of three things
  • Water
  • Eroded rock material
  • Dead stuff
  • Live stuff

5
The water component
  • The moisture content of the soil will depend upon
    several factors
  • How well drained the soil is
  • The rock composition/particle size
  • How much it rains

6
The rock component
  • Bigger rock particles such as gravel and sand
    (see chart page 237) provide good drainage and
    aeration. Its easier for roots to push through
    this type of soil.
  • Smaller rock particles such as clay and silt tend
    to pack and offer less air spaces, but are better
    at holding the minerals.

7
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8
Humus (dead stuff) in the soil
  • The dead animal and plant parts in soil act like
    a sticky glue holding the tiny rock particles
    together, making the spongy conditions needed for
    roots to grow.
  • It also holds the water and minerals needed by
    plants.

9
Soil Organisms in the soil
  • Soil aeration by worms and bugs
  • Decomposing humus by fungi and bacteria
  • Algae makes new organic compounds
  • Burrowing mammals help aerate as well
  • Plant roots penetrate the soil and secrete acids,
    breaking down rock further

10
The Soil Profile/ Soil Horizons
  • Field trip flashback
  • Remember all
  • The differences?
  • The E layer is also
  • Called the
  • Zone of Leaching

11
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12
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13
Types of Soils
  • Your text discusses the types of soils, please
    study them pg. 238-239.
  • 12 soil orders, I will discuss three common to
    WI. You should be aware of and be able to
    discuss the rest.

14
Mollisols under grasslands
15
Spodosols under pine forests
16
Alfisols deciduous forests
17
How do we use our soil?
  • 11 of our land areas is under agriculture.
  • 4 times that could be crops but it would affect
    the wildlife populations.
  • Many areas cannot support agriculture due to soil
    chemistry, topography, and rainfall.

18
How are we using our land?
  • Land use comparison
  • Wisconsin land use
  • Satellite land use
  • Study chart
  • Page 240
  • Of your text.

19
Land use correlations
  • Developed countries through technology are
    tilling less land.
  • Developing countries are destroying forests to
    create agricultural areas that are not
    sustainable.
  • 2/3 crop gains have come from better genetics and
    methods.

20
Ecological Trade offs
  • Be sure to read about the challenges facing
    developing countries.
  • How do you decide between saving the rainforest
    and feeding your people?
  • Just because you CAN cultivate land SHOULD you?

21
The Sad Truth about some areas
  • When you clear the trees from the land
  • And there isnt very deep soil
  • And theres lots of rain
  • You have about 5 years
  • Until the soil is ALL gone
  • Washed away
  • It will take 100s of years to rebuild.

22
If we acted as a team….
  • Theres plenty of land that COULD be farmed
    safely and we could feed the world.
  • I have often thought….what if we tried to feed
    the world as hard as we are trying to liberate
    Iraq? What would happen?

23
Degradation of the Land
  • What does that really mean?
  • It means the land
  • gets ruined.
  • Hmmm…..how?
  • Fertilizers , overgrazing, and erosion.
  • Why does that happen?

24
Every year our land takes a hit
  • 3 million hectares are ruined by erosion
  • 4 million hectares are turned into desert
  • 8 million hectares are turned into something
    other than crop land such as malls, homes,
    highways and parking lots

25
World Statistics on Land Degradation
  • 3oo million hectares strongly degraded
  • 910 million hectares moderatelydegraded
  • 9 million hectares not usable anymore
  • Causes
  • Water, wind, salts

26
Signs of Degradation
  • Soil is impoverished or eroded

27
Signs of Degradation
  • Water runs off the land or is contaminated

28
Signs of Degradation
  • Vegetation is diminished

29
Signs of Degradation
  • Biomass production is decreased

30
Signs of Degradation
  • Wildlife diversity diminishes

31
Impacts
  • Ranches fewer livestock
  • Farms poor crop yields
  • Nature less species
  • Page 241 of the text shows the percentages of
    degradation by country and region.

32
Major Issues to Tackle
  • Water 55
  • Wind 29 these happen naturally
  • but can be exacerbated
  • Chemical 12
  • Nutrient depletion, Salinization, acidification,
    pollution
  • Physical 4
  • Heavy machinery, cattle, waterlogging,
    solidification

33
What exactly is erosion?
  • Its the transport of soil from one place to
    another.
  • How does it happen?
  • Wind and Water carrier soil parts from high
    places to low places.
  • It has shaped the surface of our planet.
  • Is it really bad?

34
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35
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36
Wind Erosion
37
Wind Erosion
38
Wind
39
Wind
40
Water Erosion
41
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42
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43
Water Erosion across the World
44
Types of Erosion
  • Rill Erosion
  • Tiny rivers of running water make small channels
    in the soil
  • Gully Erosion
  • Rills enlarge to form big channels in the soil

45
Where is it happening?
  • Agricultural Fields/runoff
  • The fields loose soil twice as fast as it is
    being replaced.
  • Dust Storms
  • Wind carries the soil away and dumps it
    elsewhere. This can be worse than water in some
    ways.

46
US and Canada are big culprits
  • Intensive cropping/row crops
  • Deep plowing
  • Heavy herbicide applications
  • Machines create gullies
  • Abandonment of crop rotations/ issues
  • Monoculture cropping
  • check out these stats in your text pg. 242

47
What are we to do?
  • You tell me gang.
  • What can we do as individuals to help stop the
    washing away of our future?
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