Transcript Food and Agriculture Section 1

Food and Agriculture
Section 1
Food and Agriculture
Chapter 15
Food and Agriculture
Bellringer
Section 1
Food and Agriculture
Section 1
15.1 FEEDING THE WORLD
Food and Agriculture
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Section 1: Feeding the World Preview
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Feeding the World
Humans and Nutrition
Sources of Nutrition
Diets Around the
World
• The Ecology of Food
• Food Efficiency
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Old and New Foods
World Food Problems
Unequal Distribution
Droughts and Famines
The Green Revolution
Food and Agriculture
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Objectives
1. Identify the major causes of malnutrition.
2. Compare the environmental costs of producing
different types of food.
3. Explain how food distribution problems and
drought can lead to famine.
4. Explain the importance of the green revolution
Food and Agriculture
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Famine
• the widespread malnutrition and starvation in an
area
• due to a shortage of food, usually caused by a
catastrophic event.
Food and Agriculture
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Modern agriculture practices
– provide most of the world’s population with
enough food to survive.
– However, some of these practices can cause
environmental damage that eventually makes
growing food crops more difficult.
Food and Agriculture
Humans and Nutrition
• The human body uses food
– as a source of energy and
– as a source of materials for
• building and
• maintaining body tissues.
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Food and Agriculture
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Calories
• The amount of energy that is available in food is
• One Calorie is equal to
– 1,000 calories or
– one kilocalorie.
Food and Agriculture
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The three major nutrients needed
1. carbohydrates,
2. proteins, and
3. Lipids (fats , steroids)
• In addition
– smaller amounts of vitamins and minerals to
remain healthy.
Humans and Nutrition (copy to notes)
Food and Agriculture
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Malnutrition
• A disorder of nutrition
– results when a person does not consume enough of
each of the nutrients that are needed by the human
body.
• Many forms of malnutrition depending on the diet
• Example: Need 8 essential amino acids from proteins.
• This is easily done if a variety of foods is eaten.
• However, if the only sources of food is corn and rice,
which contain protein, but lacks one of the essential
amino acids.
• Amino acid deficiency can result
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Sources of Nutrition
• Diet
– the type and amount of food that a person
eats.
• A healthy diet
– maintains a balance of the right amounts of
nutrients, minerals, and vitamins.
Food and Agriculture
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Food
• Grains
– produced in the greatest amounts worldwide,
– plants of the grass family whose seeds are
rich in carbohydrates.
• Besides eating grains, most people eat
– fruits, vegetables, and smaller amounts of
meats, nuts, and other foods that are rich in
fats and proteins.
Food and Agriculture
Sources of Nutrition
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Food and Agriculture
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Diets Around the World
• People worldwide generally
– consume the same major nutrients and
– eat the same basic kinds of food.
• But, diets vary by region.
• People in more developed countries
– tend to eat more food and
– a larger proportion of proteins and fats than
people in less developed countries.
Food and Agriculture
Diets Around the World
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Food and Agriculture
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The Ecology of Food
• As the human population grows,
– farmland replaces forests and grasslands.
– Feeding everyone while maintaining natural
ecosystems becomes increasingly difficult.
• Different kinds of agriculture have
– different environmental impacts and
– different levels of efficiency.
Food and Agriculture
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Food Efficiency
• The efficiency of a given type of agriculture
– a measure of the quantity of food produced on
a given area of land with limited inputs of
energy and resources.
• An ideal food crop is
– one that efficiently produces a large amount
of food
– with little negative impact on the environment.
Food and Agriculture
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Food Efficiency
• On average,
– more energy, water, and land are used to
produced a Calorie of food from animals than
to produce a Calorie of food from plants.
• Animals that are raised for human use
– are usually fed plant matter,
– but because less energy is available at each
level on a food chain,
– only about 10 percent of the energy from the
plants gets stored in the animals.
Food and Agriculture
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Food Efficiency
Thus, a given area of land can usually produce
more food for humans when it is used to
grow plants than when it is used to raise
animals.
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• The efficiency of raising plants for food is one
reason why diets around the world are largely
based on plants.
• However, meat from animals generally provides
more nutrients per gram than most food from
plants.
Food and Agriculture
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Old and New Foods
• Researchers hope to improve the efficiency of
food production by studying plants and other
organisms that have high yield.
Food and Agriculture
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Yield
• is the amount of crops produced per unit area.
• Researchers are interested in
– organisms that
• can thrive in various climates and
• do not require large amounts of fertilizer,
pesticides, or fresh water.
– Some organisms have been a source of food
for centuries, while other sources are just
being discovered.
Food and Agriculture
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World Food Problems
• Malnourishment occurs because
– people simply do not get enough food.
• More food is needed each year to feed the
world’s growing population.
• World food production
– has been increasing for decades,
– but now food production is not increasing as
fast as the human population is increasing.
Food and Agriculture
World Food Problems
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Food and Agriculture
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Unequal Distribution
• If all the food in the world today were divided
equally among the human population,
– no one would have quite enough food for
good health.
• But food is not divided equally,
– malnutrition is largely the result of poverty.
– Even in the US, many of the poor suffer
• Wars and political strife
– can also lead to malnutrition because they
interrupt transportation systems.
Food and Agriculture
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Droughts and Famines
• A drought
– is a prolonged period during which rainfall is
below average, and
– crops grown without irrigation may produce
low yields or fail entirely.
– Is more likely to cause famine in places where
most food is grown locally.
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Droughts and Famines
• If a drought occurs,
• there may be no seed to plant crops the
following year.
• The effects of a drought can continue for
years.
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• People in a given area
– can usually survive one crop failure.
– They may have saved enough food from
previous seasons, or they may have systems
for importing food from elsewhere.
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• But several years of drought
– cause severe problems for any area of the
world.
– For example,
• after a long drought,
• the soil may be less able to support the
production of food crops.
Food and Agriculture
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The Green Revolution
• Worldwide, between 1950 and 1970,
– increases in crop yields resulted from
1. the use of new crop varieties and
2. the application of modern agriculture
techniques.
• Since the 1950s, the green revolution
– has changed the lives of millions of people.
– However, also had some negative effects.
Food and Agriculture
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For example,
• Most new varieties of grain
– produce large yields only if they receive large
amounts of water, fertilizer, and pesticides.
– In addition, the machinery, irrigation, and
chemicals required by new crop varieties can
degrade the soil if they are not used properly.
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• As a result of the overuse of fertilizers &
pesticides,
– yields from green revolution crops are falling.
– The grain production in the U.S. has
decreased since 1990,
• partly because the amount of water used
for irrigation has decreased.
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• In addition, The Green Revolution
– a negative impact on subsistence farmers, or
farmers who grow only enough food for local
use.
– Before the green revolution,
• subsistence farmers worked most of the
world’s farms.
• But they could not afford the equipment,
water, and chemicals needed to grow new
crop varieties.
Math Practice
Known
Unknown
Solution
Quick Check 15.1
Food and Agriculture
Bellringer
Section 1
Food and Agriculture
Section 2: Crops and Soil Preview
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Agriculture: Traditional/Modern
Fertile Soil: The Living Earth
Soil Erosion: A Global Problem
Land Degradation
Soil Conservation
Enriching the Soil
Salinization
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Food and Agriculture
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Objectives
1. Distinguish between traditional and modern
agricultural techniques.
2. Describe fertile soil.
3. Describe the need for soil conservation.
Food and Agriculture
Crops and Soil
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Food and Agriculture
Arable land
• is farmland
• limited area of arable land.
• Dilemma
– As the human population increases,
– the amount of arable land per person
decreases.
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Food and Agriculture
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Agriculture: Traditional
• The basic processes of farming include plowing,
fertilization, irrigation, and pest control.
– Plows helps
• mixing soil nutrients,
• loosening soil particles, and
• uprooting weeds.
– Organic fertilizers, such as manure,
– Fields are irrigated by ditches.
Food and Agriculture
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Agriculture: Modern
• The basic processes of farming are now carried
out using modern agricultural methods.
– powered by fossil fuels
– Synthetic chemical fertilizers have replaced
manure and plant wastes
• A variety of overhead sprinklers and drip
systems may be used for irrigation.
• Synthetic chemicals are used to kill pests.
Food and Agriculture
Fertile Soil:
– Supports the growth of healthy plants
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Food and Agriculture
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6 Basic Layers
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5.
6.
Surface liter
Topsoil
Zone of leaching
Subsoil
Rock particles
Bedrock, which is the solid rock from which
most soil originally forms.
Food and Agriculture
Fertile Soil: The Living Earth
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Food and Agriculture
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Topsoil
• surface layer of the soil,
• usually richer in organic matter
• composed of
– living organisms,
– rock particles,
– water,
– air, and
– organic matter, such as dead or decomposing
organisms.
Food and Agriculture
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Soil
• forms when rock is broken down into smaller
and smaller fragments by
– wind,
– water, and
– chemical weathering.
• happens when the minerals in rock react
chemically with substances to form new
materials.
• Temperature changes & moisture can cause
rock to crack and break apart.
• a few centimeters of soil can take hundreds or
even thousands of years to form
Food and Agriculture
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Other processes affected topsoil
• the rock particles supply mineral nutrients
• Fungi and bacteria decompose dead plants as
well as organic debris  nutrients
• Earthworms, insects, and other small animals
help by
– breaking up the soil and
– allowing air and water into it.
Food and Agriculture
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Food and Agriculture
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Soil Erosion: A Global Problem
• a process in which materials of the Earth’s
surface are
and transported from one
– Loosened,
place to another by a natural
– dissolved, or agent, such as wind, water,
ice, or gravity.
– worn away
• In the U.S.,
– About half of the original topsoil has been lost
to erosion in the past 200 years.
– Almost all farming methods increase the rate
of soil erosion.
Food and Agriculture
Soil Erosion: A Global Problem
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Food and Agriculture
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Land Degradation
• Happens when human activity or natural
processes damage the land
– it can no longer support the local ecosystem.
– In areas with dry climates, desertification can
occur.
• Desertification
– A process by which human activities or
climatic changes make arid or semiarid areas
more desertlike.
– is causing some of our arable land to
disappear.
Food and Agriculture
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For example of Land Degradation
• In the past, people who
– lived in the drier part of the Sahel region in
Africa grazed animals,
– Lived in the wetter part planted crops.
• .
Food and Agriculture
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For example of Land Degradation
• The grazing animals
– were moved from place to place to find fresh
grass.
• The cropland
– was planted for only a few years, and
– then allowed to lie fallow, or to remain
unplanted, for several years.
• These methods allowed the land to adequately
support the people in the Sahel.
Food and Agriculture
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But the population in the region has grown
• The land is being farmed, grazed, and
deforested faster than it can regenerate.
– Crops
• are planted too frequently and
• fallow periods are being shortened or
eliminated completely.
As a result, the soil is losing fertility and productivity.
Food and Agriculture
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But the population in the region has grown
• Because of overgrazing,
– the land has fewer plants to hold the topsoil in
place.
– large areas
•  desert and
• can no longer produce food.
Food and Agriculture
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Many ways to Conserve Soil
• Soil usually erodes downhill,
– many techniques are designed to prevent
downhill erosion.
Food and Agriculture
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Many ways to Conserve Soil
• For example,
– soil-retaining terraces can be build across a
hillside.
– On gentler slopes, contour plowing, which
consists of plowing across the slope of a hill
instead of up and down the slope, can be
used.
Food and Agriculture
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Soil Conservation
• An even more effective method of plowing is
leaving strips of vegetation across the hillside
instead of plowing the entire slope.
• These strips catch soil and water that run down
the hill.
Food and Agriculture
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No-till Farming
• a crop is harvested without turning the soil over,
as in traditional farming.
• Later, the seeds of the next crop are planted
among the remains of the previous crop.
• The remains of the first crop hold the soil in
place while the new crop develops.
• saves time and reduces soil erosion,
Food and Agriculture
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No-till Farming
• Disadvantages
– not suited for all crops.
– Not good for soil that is too densely packed
Food and Agriculture
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Enriching the Soil
• traditionally
– Added organic matter would decompose, adding
nutrients and improving the soil texture.
• However, inorganic fertilizers containing
1. nitrogen,
2. phosphorous, &
3. potassium
– Doubles food production
• If erosion occurs in areas fertilized with inorganic
materials, waterways may become polluted.
Food and Agriculture
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Enriching the Soil
• Over the past 50 years, the use of such
inorganic fertilizers has increased rapidly.
Food and Agriculture
Enriching the Soil
• A modern method
– uses both organic and
inorganic materials
– adds compost and chemical
fertilizers to the soil.
• Compost
– a mixture of decomposing
organic matter, such as
manure and rotting plants,
– used as fertilizer and soil
conditioner.
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Food and Agriculture
Many cities and industries
– compost yard and crop wastes.,
– sell or give away,
– saving costly land fill space.
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Food and Agriculture
Salinization
•The accumulation of salts in the soil
• Major problem in places
that have
– low rainfall and
– naturally salty soil.
• When water evaporates
from irrigated land, salts
are left behind.
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Food and Agriculture
Picture Salinization
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Food and Agriculture
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Salinization
• can be slowed if irrigation canals are lined to
prevent water from seeping into the soil, or
• if the soil is watered heavily to wash out salts.
Quick Check 15.2 a
Food and Agriculture
Section 1
Section 2: Crops and Soil Preview, continued
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Pest Control
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Pesticides
Pesticide Resistance •
Human Health
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Concerns
• Pollution and
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Persistence
• Biological Pest Control
Integrated Pest
Management
Engineering a Better
Crop
Implications of Genetic
Engineering
Sustainable Agriculture
Food and Agriculture
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Objectives 15.2 a
1. Explain the benefits and environmental impacts
of pesticide use.
2. Explain what is involved in integrated pest
management.
3. Explain how genetic engineering is used in
agriculture.
Food and Agriculture
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Pest Control
• Worldwide,
– pests destroy about one-third of the world’s
potential food harvest.
• A pest - any organism
– That occurs where it is not wanted or
– That occurs in large enough numbers to
cause economic damage.
– Many types: plants, fungi, insects, &
microorganisms.
Food and Agriculture
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Pesticides
• a poison used to destroy pests, such as
– insects,
insecticides
– rodents,
rodenticides
– Weeds;
herbicides.
• Pesticides, however, can also harm beneficial
plants and insects, wildlife, and even people.
Food and Agriculture
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Pesticide Resistance
• Over time, may make the pest problem worse.
• May evolve resistance,
• Fact:
– More than 500 species of insects have
developed resistance to pesticides since the
1940s.
Food and Agriculture
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Human Health Concerns
• Pesticides
– are designed to kill organisms,
– may also be dangerous to humans.
• Cancer rates among children
– in areas where large amounts of pesticides
are used on crops
– are sometimes higher than the national
average.
• People who apply pesticides need to follow
safety guidelines to protect themselves from
contact with these chemicals.
Food and Agriculture
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Pollution and Persistence
• A persistent pesticide
– does not break down easily or quickly in the
environment into harmless chemicals
– Will accumulate in the water and soil.
– Increases possibility of harming people and
other organisms.
• Some pesticides have been banned in the
United States for decades but can still be
detected in the environment.
Food and Agriculture
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Biological Pest Control
• Every pest has
– enemies in the wild, and
– these enemies can sometimes be used to
control pest populations.
• Biological pest control
– includes the use of
• pathogens,
• plant defenses,
• chemicals from plants,
• and the disrupting of insect breeding
Food and Agriculture
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Integrated Pest Management
• a modern method of controlling pests
• The goal
– not to eliminate pest populations
– but to reduce pest damage to a level that
causes minimal economic damage.
• Such programs can include a mix of
1. farming methods,
2. biological pest control, and
3. chemical pest control.
Food and Agriculture
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Integrated Pest Management
1. Biological methods
– Natural predators, pathogens, and parasites
of the pest may be introduced.
2. Cultivation controls,
– such as vacuuming insects off the plants,
3. Small amounts of insecticides
– Last resort,
– These insecticides are changed over time to
reduce the ability of pests to evolve
resistance.
Food and Agriculture
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Engineering a Better Crop
• Genetic engineering
– a technology in which the genome of a living
cell is modified for medical or industrial use.
– Used to transfer desirable traits, such as
resistance to certain pests, from one
organism to another.
• Plants that result from genetic engineering are
called genetically modified (GM) plants.
Food and Agriculture
Engineering a Better Crop
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Food and Agriculture
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Implications of Genetic Engineering
• In the United States, we now eat and use
genetically engineered agricultural products
everyday.
• Many of these products,
– have not been fully tested for their
environmental impacts.
– Some scientists warn that these products will
cause problems in the future.
Food and Agriculture
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Sustainable Agriculture
• Farming that conserves natural resources and
helps keep the land productive indefinitely
• Involves
– planting productive,
– pest-resistant crop varieties that require little
energy,
– pesticides,
– fertilizer, and
– water.
Quick Check 15.2
Food and Agriculture
Section 3: Animals and Agriculture
Preview
• Bellringer
• Objectives
• Animals and Agriculture
• Food from Water
• Overharvesting
• Aquaculture
• Livestock
Section 1
Food and Agriculture
Section 3: Animals and Agriculture
Preview
• Ruminants
• Poultry
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Food and Agriculture
Bellringer
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Food and Agriculture
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Objectives
• Explain how overharvesting affects the supply
of aquatic organisms used for food.
• Describe the current role of aquaculture in
providing seafood.
• Describe the importance of livestock in
providing food and other products.
Food and Agriculture
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Animals and Agriculture
• Food from animals has been the basis of life for
some human populations for centuries.
• Our ancestors obtained animal protein by
hunting and fishing. Today, most people get
animal protein from domesticated species.
• Domesticated describes organisms that have
been bred and managed for human use.
Food and Agriculture
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Food from Water
• Because fish are an important food source for
humans, the harvesting of fish has become an
important industry worldwide.
• However, when too many fish are harvested
over a long period of time, ecological systems
can be damaged.
Food and Agriculture
Food from Water
The North Atlantic cod fishery has collapsed
because too many fish were harvested over time.
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Food and Agriculture
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Overharvesting
• Overharvesting is the catching or removing
from a population more organisms than the
population can replace.
• Many governments are now trying to stop
overharvesting. They have created no-fishing
zones, so that fish populations can recover.
Food and Agriculture
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Aquaculture
• Aquaculture is the raising of aquatic plants and
animals for human use or consumption.
• Fish and other aquatic organisms provide up to
20 percent of the animal protein consumed
worldwide.
• Aquaculture may be one solution to the
overharvesting of fish and other organisms
in the world’s oceans.
Food and Agriculture
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Aquaculture
• Aquaculture is not a new idea.
• This practice probably began in China about
4,000 years ago.
• Today, China leads the world in using
aquaculture to produce freshwater fish.
Food and Agriculture
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Aquaculture
• There are a number of different methods of
aquaculture. Among these are
• Fish farming
• Fish ranching
• Fish farms generally consist of many individual
ponds that each contain fish at a specific stage
of development. Fish grow to maturity in the
ponds and are then harvested.
• Fish ranches raise fish to a certain age, release
them to the ocean, and then harvest the adults
when they return to their birthplace to breed.
Food and Agriculture
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Aquaculture
• As with other methods of food production,
however, aquaculture can cause environmental
damage if not managed properly.
• Aquatic organisms can produce a large
amount of waste, which can be a source of
pollution.
• Because aquaculture requires so much water,
the process can deplete local water supplies.
• Despite these problems, aquaculture will
continue to be an important source of protein for
the human
diet.
Food and Agriculture
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Livestock
• Livestock is the term given to domesticated
animals that are raised to be used on a farm or
ranch or to be sold for profit.
• Populations of livestock have changed
dramatically in the last 40 years.
• Large livestock operations produce most of the
meat that is consumed in developed countries.
Food and Agriculture
Livestock
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Food and Agriculture
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Livestock
• In developing countries, livestock not only
provide leather, wool, eggs, and meat, but also
serve other functions.
• Some livestock are used as draft animals to pull
carts and plows.
• Other livestock provide manure as the main
source of plant fertilizer or as a fuel for cooking.
Food and Agriculture
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Ruminants
• Ruminants are cud-chewing mammals that
have a three- or four-chambered stomach.
• Cattle, sheep, and goats are examples of
ruminants.
• Cud is the food that these animals regurgitate
from the first chamber of their stomachs and
chew again to aid digestion.
• When we eat the meat of ruminants, we are
using them to convert plant material, such as
grass stems and woody shrubs, into food that
we can digest—such as beef.
Food and Agriculture
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Ruminants
• Humans have created hundreds of breeds of
cattle that are suited to life in different climates.
• Worldwide meat production per person has
increased
significantly since 1950.
Food and Agriculture
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Poultry
• Since 1961, the population of chickens
worldwide has increased to a greater
percentage than the population of any other
livestock.
• Chickens are a type of poultry, domesticated
birds raised for meat and eggs.
• In more-developed countries, chickens and
turkeys are usually raised in factory farms.
Food and Agriculture
Graphic Organizer
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Quick Check 15.3