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Soil Erosion and Degradation

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Soil Erosion and Degradation Soil Erosion and Degradation PA Standards 4.2.12.C: Renewable and Nonrenewable Resources 4.4.10.B: Agriculture and Society The nation ... – PowerPoint PPT presentation

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Title: Soil Erosion and Degradation


1
Soil Erosion and Degradation
2
Soil Erosion and Degradation
  • PA Standards
  • 4.2.12.C Renewable and Nonrenewable Resources
  • 4.4.10.B Agriculture and Society
  • The nation that destroys its soil destroys
    itself.
  • - Franklin D. Roosevelt (1937)
  • Analyze factors that influence the availability
    of natural resources.
  • Assess the influence of agriculture science on
    farming practices (plowing).

3
Key Questions
  • How are soils being degraded and eroded?
  • What can be done to reduce these losses?

4
Consider this
  • Human activity accelerates natural soil erosion.
  • One-third to one-half of worlds croplands are
    losing topsoil faster than it is being renewed by
    natural processes .

5
HOW MUCH OF THE EARTH IS AVAILABLE FOR FARMING?
  • Question How much of the Earth is available for
    farming?
  • http//www.agclassroom.org/teacher/screensavers/ap
    ple.htm

6
How are soils being degraded and eroded?
7
SOIL EROSION AND DEGRADATION
  • Soil erosion lowers soil fertility and can
    overload nearby bodies of water with eroded
    sediment.
  • Sheet erosion surface water or wind peel off
    thin layers of soil.
  • Rill erosion fast-flowing little rivulets of
    surface water make small channels.
  • Gully erosion fast-flowing water join together
    to cut wider and deeper ditches or gullies.

8
SOIL EROSION AND DEGRADATION
  • Soil erosion is the movement of soil components,
    especially surface litter and topsoil, by wind or
    water.
  • Soil erosion increases through activities such as
    farming, logging, construction, overgrazing, and
    off-road vehicles.

9
Global Outlook Soil Erosion
  • Soil is eroding faster than it is forming on more
    than one-third of the worlds cropland.

10
What can be done to reduce these losses?
11
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
  • Modern farm machinery can plant crops without
    disturbing soil (no-till and minimum tillage.
  • Conservation-tillage farming
  • Increases crop yield.
  • Raises soil carbon content.
  • Lowers water use.
  • Lowers pesticides.
  • Uses less tractor fuel.

12
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
  • Terracing, contour planting, strip cropping,
    alley cropping, and windbreaks can reduce soil
    erosion.

13

Biodiversity Loss
Soil
Air Pollution
Human Health
Water
Loss and degradation of grasslands, forests, and
wetlands
Erosion
Water waste
Nitrates in drinking water
Greenhouse gas emissions from fossil fuel use
Loss of fertility
Aquifer depletion
Pesticide residues in drinking water, food, and
air
Salinization
Increased runoff and flooding from cleared land
Other air pollutants from fossil fuel use
Waterlogging
Desertification
Fish kills from pesticide runoff
Sediment pollution from erosion
Contamination of drinking and swimming water with
disease organisms from livestock wastes
Greenhouse gas emissions of nitrous oxide from
use of inorganic fertilizers
Fish kills from pesticide runoff
Killing wild predators to protect livestock
Surface and groundwater pollution from pesticides
and fertilizers
Belching of the greenhouse gas methane by cattle
Loss of genetic diversity of wild crop strains
replaced by monoculture strains
Bacterial contamination of meat
Overfertilization of lakes and rivers from runoff
of fertilizers, livestock wastes, and food
processing wastes
Pollution from pesticide sprays
14
Review Key Questions
  • How are soils being degraded and eroded?
  • What can be done to reduce these losses?

15
Thought Problems
  • How does deforestation, over farming, and over
    grazing contribute to erosion or arable land?
  • If we exhaust the food-producing resources we
    have now, wont science devise new ways to
    increase food production as it has been done in
    the past?
  • What conclusions can we draw about the
    relationship between a growing population and a
    shrinking amount of land capable of growing food
    for those people?
  • How can we preserve farmland?

16
Thought Problems - Answers
  • How does deforestation, over farming, and over
    grazing contribute to erosion or arable land?
  • 1/32 of land is suitable for agriculture
    deforestation increases erosion, over farming
    decreases land nutrients, and over grazing
    increases erosion and decreases nutrients
  • If we exhaust the food-producing resources we
    have now, wont science devise new ways to
    increase food production as it has been done in
    the past?
  • Hydroponics genetics decrease nutrients,
    decrease health in livestock increase in
    antibiotics
  • What conclusions can we draw about the
    relationship between a growing population and a
    shrinking amount of land capable of growing food
    for those people?
  • Famine decreased nutrients different types of
    food
  • How can we preserve farmland?
  • No plow farming stop wasting, rotate crops
    conservation tillage, best management practices
    limit development buy local eat lower on the
    food chain

17
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18
Case Study Soil Erosion in the U.S. Some
Hopeful Signs
  • Soil erodes faster than it forms on most U.S.
    cropland, but since 1985, has been cut by about
    40.
  • 1985 Food Security Act (Farm Act) farmers
    receive a subsidy for taking highly erodible land
    out of production and replanting it with soil
    saving plants for 10-15 years.

19
Desertification Degrading Drylands
  • About one-third of the worlds land has lost some
    of its productivity because of drought and human
    activities that reduce or degrade topsoil.

20

Very severe
Severe
Moderate
21
Salinization and Waterlogging
  • Repeated irrigation can reduce crop yields by
    causing salt buildup in the soil and waterlogging
    of crop plants.

22

Solutions
Soil Salinization
Cleanup
Prevention
Reduce irrigation
Flush soil (expensive and wastes water)
Stop growing crops for 25 years
Switch to salt-tolerant crops (such as barley,
cotton, sugarbeet)
Install underground drainage systems (expensive)
23
Salinization and Waterlogging of Soils A
Downside of Irrigation
  • Example of high evaporation, poor drainage, and
    severe salinization.
  • White alkaline salts have displaced cops.

24
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
  • Fertilizers can help restore soil nutrients, but
    runoff of inorganic fertilizers can cause water
    pollution.
  • Organic fertilizers from plant and animal
    (fresh, manure, or compost) materials.
  • Commercial inorganic fertilizers Active
    ingredients contain nitrogen, phosphorous, and
    potassium and other trace nutrients.

25
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
  • Since 1950, high-input agriculture has produced
    more crops per unit of land.
  • In 1967, fast growing dwarf varieties of rice and
    wheat were developed for tropics and subtropics.

26
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
  • Lack of water, high costs for small farmers, and
    physical limits to increasing crop yields hinder
    expansion of the green revolution.
  • Since 1978 the amount of irrigated land per
    person has declined due to
  • Depletion of underground water supplies.
  • Inefficient irrigation methods.
  • Salt build-up.
  • Cost of irrigating crops.

27
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
  • Modern agriculture has a greater harmful
    environmental impact than any human activity.
  • Loss of a variety of genetically different crop
    and livestock strains might limit raw material
    needed for future green and gene revolutions.
  • In the U.S., 97 of the food plant varieties
    available in the 1940 no longer exist in large
    quantities.

28
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