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Soil Conservation

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Title: Soil Conservation


1
Soil Conservation
2
"A nation that destroys its soil destroys
itself." - President Franklin D. Roosevelt, 1937
Why is soil conservation important?
3
The Value of Soil
  • Soil is one of Earths most valuable natural
    resources, Why?
  • Natural resourceanything in the environment that
    humans use.
  • Plants depend on soil to live and grow.
  • Humans and animals depend on plants-or on other
    animals that depend on plants-for food.
  • Fertile soil is in limited supply not much land
    for farming.
  • Takes a long time for soil to form.

4
Soil Damage and Loss
  • Human activities and changes in the environment
    can affect the soil.
  • The value of soil is reduced when soil loses its
    fertility and when topsoil is lost due to erosion.

5
Loss of Topsoil
  • Whenever soil is exposed, water and wind can
    quickly erode it.
  • Plant cover can protect soil from erosion.
  • Plants break the force of falling rain, and plant
    roots hold the soil together.
  • Wind is another cause of soil loss.
  • Wind erosion can occur in areas with dry
    conditions.

6
Sheet erosion is the removal of the thin layer of
topsoil by raindrop splash or water run-off.
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Wind erosion is the detachment and movement of
soil by wind.
8
Gully erosion occurs when small streams unite and
create a stronger flow, cutting a channel down
which water flows during or just after rain
9
The Dust Bowl
  • Great Plains farmers settled there
    because of available fertile soil.
  • Region has 8-year drought 1931-1939.
  • Plowing removed the grass from the Great Plains
    and exposed the soil.
  • In times of drought, the topsoil dried out and
    turned to dust and blew away.

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The Dust Bowl
  • By 1930, almost all of the Great Plains had been
    turned into farms or ranches.
  • Long drought turned the soil to dust.
  • The wind blew the soil east in great, black
    clouds
  • Dust Bowl ruined farmland in parts of the Great
    Plains.
  • Dust Bowl helped people realize the value of
    soil.
  • Farmers adopted new methods to help save soil.
  • Dust Bowl occurred during the Great Depression

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Worldwide, an estimated 26 billion tons of
topsoil are washed or blown off cropland each
year. Every year 6 million hectares of productive
dryland become desert.
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Improve soil management
Practice contour plowing reduced tillage or
no tillage, using windbreaks to reduce wind
speeds at the land surface, allowing soils to
rest promote humus production
17
Soil Conservation
  • Since the Dust Bowl, farmers have adopted modern
    methods of soil conservation
  • Soil conservation management of soil to prevent
    its destruction.
  • Soil can be conserved by
  • Contour plowing
  • Conservation plowing
  • Crop rotation

18
Legumes
A plant that has pods as fruits and roots that
bear nodules containing nitrogen-fixing bacteria
Crop Rotation
Intercropping
19
Nitrogen Fixation with Legumes
  • Biological nitrogen fixation can be represented
    by the following equation, in which two moles of
    ammonia are produced from one mole of nitrogen
    gas, at the expense of 16 moles of ATP and a
    supply of electrons and protons (hydrogen ions)
  • N2 8H 8e- 16 ATP 2NH3 H2 16ADP 16
    Pi

Video
20
Contour Plowing
  • Contour plowingfarmers plow their fields along
    the curves of a slope.
  • This helps slow the runoff of excess rainfall and
    prevents it from washing the soil away.

21
Conservation Tillage
  • In conservation tilage, farmers disturb the soil
    and its plant cover as little as possible.
  • Dead weeds and stalks of the previous years crop
    are left in the ground to help return soil
    nutrients, retain moisture, and hold soil in
    place.
  • Also called low-till or no-till plowing,
    reduced- tillage.

22
Crop Rotation
  • Crop rotation-a farmer plants different crops in
    a field each year.
  • Different types of plants absorb different
    amounts of nutrients from the soil.
  • Corn and cotton-absorb large amounts of
    nutrients.
  • Year after planting these crops, farmer plants
    crops that use fewer nutrients, such as oats,
    barley, or rye.
  • The year after that the farmer sows legumes such
    as alfalfa or beans to restore the nutrient
    supply.

23
Cover Crops
  • A cover crop is a crop planted primarily to
    manage soil erosion, soil fertility, soil
    quality, water, weeds, pests, diseases,
    biodiversity and wildlife in an agroecosystem, an
    ecological system managed and largely shaped by
    humans across a range of intensities to produce
    food, feed, or fiber.

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Clips
  • http//www.brainpop.com/
  • Soil
  • Erosion
  • Natural resources
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