Chapter 4
Land and Soil
Resources
Section 1
Conserving Land and Soil
3 uses that change the land are
agriculture, development, and mining.
 Less than 1/3 of Earth can be farmed.
New farmland must be created for the
growing populations.
 In the U.S. about a million hectares of
farmland is developed each year.
 Development is the construction of
buildings, roads, bridges, dams and other
structures.

Mining

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Mining is the removal of nonrenewable resources
such as iron, copper, and coal from the land.
Strip mining removes a strip of land to obtain minerals, and
then replacing the strip. This exposes the soil and can be
washed or blown away. These areas can remain barren for
years before they are rich enough to support the growth of
new plants.
Protecting the Soil
 Poor
soil management can result in 3
problems: erosion, nutrient
depletion, and desertification.
Terms

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Litter: The very top layer of dead leaves and
grass.
Topsoil: A mixture of rock fragments, nutrients,
water, air, and decaying animal and plant matter.
Subsoil: Below the topsoil, contains rock
fragments, water and air, but less animal and
plant matter.
Bedrock: Soil that makes up Earth’s crust.
It takes hundreds of years to form just a few
centimeters of new soil.
Erosion
Is the process by which water, wind, or
ice moves particles of rocks or soil.
Nutrient Depletion

Nutrient Depletion: When farmers plant the
same crops in a field year after year. As a result,
the plants use more nutrients than the
decomposers can replace. The soil becomes less
fertile.
Desertification
 The
advance of desertlike conditions
into areas that previously were
fertile.
Restoring the Land
 Land
Reclamation: The process of
restoring an area of land to a more
natural, productive state.
 Smooth and replace strip mines with
new topsoil.
 Plant grass.
Review
 List
three ways that people use land.
 What are 3 problems that can occur
when topsoil is not properly
managed?
 Describe the effects of strip mining.
 Describe two methods for reducing
soil erosion.
Section 2
Solid Waste
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Every hour people throw away 2.5 million plastic bottles.
Every year people throw away enough white paper to build
a wall 4 meters high that stretches coast to coast.
Every year people throw away 1.6 billion pens, 2.9 million
tons of paper towels, and 220 million automobile tires.
Problem of Waste Disposal
 Municipal
solid waste : Waste
materials produced in homes,
businesses, schools, and other places
in a community.
Three methods of handling solid waste.

You can bury it, burn it, or recycle waste.

Leachate: Polluted liquid, from the rainwater that has
dissolved chemicals from the waste.
 Sanitary
Landfills: Holds municipal solid
wastes, construction debris, and some
types of agricultural and industrial waste.
Incineration

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
The burning of solid waste is called incineration.
The advantages of incinerators is that they do not
take up as much space as landfills, they do not
pose the risk of polluting groundwater, and the
heat they produce can generate electricity.
Disadvantage is that they are more expensive to
build.
Recycling
Recycling: The process of reclaiming raw
materials and reusing them.
 Biodegradable: A substance that can be
broken down and recycled by bacteria and
other decomposers.
 Most recycling focuses on 4 major
categories of products: metal, glass,
paper, and plastic.

Products to Recycle
Metal

Metals such as iron and aluminum can be melted
and reused. Recycling metal saves money and
causes less pollution than making new metal.
Glass


Glass is one of the easiest products to recycle
because it can be melted down over and over to
make new glass containers.
Recycling glass is less expensive than making
glass from raw materials. Less energy is
required. It also reduces the environmental
damage caused by mining for sand, soda, and
limestone.
Paper

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Most paper products can only be recycled a few
times.
Each time the paper is recycled to make pulp, the
new paper is rougher, weaker, and darker.
It takes about 17 trees to make one metric ton of
paper.
Plastics
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When oil is refined to make gasoline and other
petroleum products, solid materials called resins
are left over.
These resins can be heated, stretched, and
molded into plastic products.
Numbers are found on the bottom of plastic
containers. The numbers 1 & 2 are made from
plastics that are often recycled.
What Can You Do?
These are sometimes called the 3 R’s –
Reduce, Reuse and Recycle.
 Reduce: Refers to creating less waste in
the first place. (Use cloth shopping bags
than disposable paper or plastic bags.
 Reuse: Find another use for the object
rather than discarding it.( Example ???)
 Recycle: Reclaiming raw materials to
create new products.

Composting
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Composting: Is the process of helping the
natural decomposition processes break down
many forms of waste.
Compost is an excellent natural fertilizer for
plants.
Examples: (Raked leaves, grass, food waste,
eggshells, coffee grounds and cow manure)
Section 3
Hazardous Wastes
 Hazardous
wastes are classified into
4 categories: Toxic, Explosive,
Flammable, and Corrosive.
Toxic Waste
 Are
poisonous wastes that an
damage the health of humans and
other organisms.
Explosive Waste
 Are
waste that react very quickly
when exposed to air or water, or that
explode when they are dropped.
Flammable Waste
 Are
waste that catch fire easily and
can begin burning at fairly low
temperatures.
Corrosive Waste
 Are
waste that dissolve or eat
through many materials.
Radioactive Waste

Are waste that contain unstable atoms. They require
special disposal.
Health Effects
 Short-term
exposure to hazardous
wastes, may cause irritation or more
severe health problems.
 Long-term exposure to hazardous
wastes, may cause diseases, such as
cancer,, and may damage body
organs, including the brain, liver,
kidneys, and lungs.
Disposal of Hazardous Waste
 Methods
of hazardous waste disposal
include burial in landfills,
incineration, and breakdown by living
organisms. Another method involves
storing liquid wastes in deep rock
layers.
 Scientists have not been able to
develop completely safe methods for
disposing of radioactive waste.