Transcript Ch 4-1 Envir

Chapter 4
Land and Soil Resources
Section 1
Conserving Land and Soil
Notes 4-1
Types of Land Use
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Agriculture:
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Land is the source of most of the food we eat
Less than 1/3 of land can be farmed
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New farm land must be made
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The rest is either too dry, wet, salty or mountainous
Clearing land, draining wetlands or irrigating deserts
Land also is used for grazing
Types of Land Use
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Development:
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Construction of buildings, roads and bridges
Each year in the US an area half the size of NJ is
developed
They use farmland, forests and wetlands
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This destroys ecosystems and habitats
Types of Land Use
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Mining:
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Removal of nonrenewable resources such as iron,
copper or coal from the land
Strip mining:
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Removing a strip of land to get the minerals and then
replacing that strip
Causes erosion
May remain barren without growth for years and years
Underground mining:
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Using a tunnel or shaft to carry up the minerals from
under the ground
What are the three types
of land use?
Protecting the Soil
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Soil is a complex ecosystem
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Made of living and nonliving things
 Minerals and nutrients
 Absorbs, filters and stores water
 Bacteria, fungi and other organisms live there
Protecting the Soil
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Layers of soil
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Litter: dead leaves and grass
Topsoil: mixture of rock and minerals pieces,
living organisms, water, air and decaying matter
Subsoil: same material as topsoil but less decaying
matter
Bedrock: rock that makes up the earth’s crust
Takes 100’s of years to make a few cm of top
soil
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Lichen and worms break up the rock into soil
Poor Soil Management
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Erosion:
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Process by which water, wind or ice moves
particles of rock or soil
Plant roots hold soil in place
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Without plants, the soil gets moved away
Soil Conservation (p. 117)
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Strip cropping
Contour plowing
Windbreaks
terracing
Poor Soil Management
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Nutrient Depletion:
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Soil becomes less fertile
Caused by plants using more nutrients than
decomposers can replace into the soil
Prevention:
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Leave fields fallow – unplanted with crops
Leave unused parts of crops in fields
Crop rotation – plant different crops in a field each year
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Corn one year, beans another, alfalfa the next
Poor Soil Management
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Desertification:
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Loss of so much topsoil that plants can no longer
grow there
Major cause is over grazing by cattle and sheep
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Strip mining and cutting down trees are also a cause
Severe in central Africa
In US, land 12 times larger than Texas has been
affected
Restoring the Land
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Land reclamation:
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Process of restoring an area of land to a more
natural, productive state
Can also restore habitats for wildlife
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Former mines are now agricultural land, ponds or
forests
Ex: Sheppton, PA