Download Soil Conservation - Mr. Phillips

Soil Conservation
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What should
you know by
the end
Why is soil conservation important?
What caused the Great Dust Bowl?
What steps can we take to mitigate soil erosion?
What steps can we take to prevent soil from
losing its fertility?
Introduction
• Prairie soil = very fertile
– Rich in humus because of the tall grass
• Sod=thick mass of tough roots at the surface of
the soil.
• Sod keeps soil in place and holds onto moisture.
• Prairies cover Iowa, Illinois, Kansas, Nebraska,
and North and South Dakota.
• Farms growing crops such as corn, soybeans, and
wheat have replaced prairies.
The Value of Soil
• Natural resource=anything in the environment
that humans use.
• Earth’s natural resources? Timber, minerals, oil,
air, water, etc…
• Soil is one of Earth’s most valuable natural
resources, Why?
• 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. Why? – Talk to
partner
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.
Loss of Fertility
• Soil that has lost its fertility is said to be exhausted.
• Soil loss occurred in the South in the late 1800’s.
• Soils in which only cotton had been grown were
exhausted.
• George Washington Carver developed new crops and
farming methods that helped restore soil fertility in the
south.
• Peanuts were used to help make the soil fertile again.
• Peanut plants are legumes.
• Legumes have small lumps on their roots that
contain nitrogen-fixing bacteria.
• Nitrogen is an important nutrient for plants.
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.
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.
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
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
Contour Plowing
• Contour plowing=farmers 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.
• http://www.teachertube.com/view_video.
php?viewkey=06d988f6f73518b7ab35
Conservation Plowing
• In conservation plowing, farmers disturb
the soil and its plant cover as little as
possible.
• Dead weeds and stalks of the previous
year’s 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.
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.
Why is soil conservation
important?
• Soil provides the nutrients need to grow
crops and plants
• Plants depend on soil to live and grow
• Humans and animals depend on plants to
live
• Limited supply
• Soil takes along time to create
What caused the Great Dust Bowl?
• Plowing removed the grass
• Drought occurred, turning soil into dust
What steps can we take to mitigate
soil erosion?
• Cover landscape with plants, roots hold soil
in place
• Plant trees to break up wind
• Contour plowing
• Conservation plowing
– (Stalks other residue left on field prevent wind
and water from eroding soil
What step can we take to prevent
soil from losing its fertility?
• Crop rotation
– Year 1 Corn ( Uses lots of nutrients in soil)
– Year 2 oats , barley, rye ( uses less nutrients)
– Year 3 the legumes (Peanuts,, alfalfa, beans add nutrients back to soil)
• Conservation plowing
– (Stalks other residue left on field to decompose
and add nutrients back to soil)