Identify the major causes of malnutrition.

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• Identify the major causes of malnutrition.
• Compare the environmental costs of producing
  different types of food.
• Explain how food distribution problems and
  drought can lead to famine.
• Explain the importance of the green revolution.

Section 1
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Feeding the World

• Famine is the widespread malnutrition and
  starvation in an area due to a shortage of food,
  usually caused by a catastrophic event.
• Modern agriculture practices provide most of the
  worlds population with enough food to survive.
• However, some of these practices can cause
  environmental damage that eventually makes
  growing food crops more difficult.

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Humans and Nutrition

• The human body uses food both as a source of
  energy and as a source of materials for building
  and maintaining body tissues.
• The amount of energy that is available in food is
  expressed in Calories. One Calorie is equal to
  1,000 calories or one kilocalorie.

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Humans and Nutrition
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Humans and Nutrition

• Malnutrition is a disorder of nutrition that
  results when a person does not consume enough of
  each of the nutrients that are needed by the
  human body.

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Sources of Nutrition
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Diets Around the World
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World Food Problems

• Some people become malnourished because they
  simply do not get enough food.
• More food is needed each year to feed the worlds
  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.

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World Food Problems
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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, and malnutrition
  is largely the result of poverty. Even in the
  United States, many poor people suffer from
  malnutrition.
• Wars and political strife can also lead to
  malnutrition because they interrupt
  transportation systems.

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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.
• A drought is more likely to cause famine in
  places where most food is grown locally.
• 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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The Green Revolution

• Worldwide, between 1950 and 1970, increases in
  crop yields resulted from the use of new crop
  varieties and the application of modern
  agriculture techniques.
• These changes were called the green revolution.
  Since the 1950s, the green revolution has changed
  the lives of millions of people.
• However, the green revolution also had some
  negative effects.

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The Green Revolution

• 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.
• As a result of the overuse of fertilizers and
  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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The Green Revolution

• In addition, the green revolution had 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 worlds farms.
• But they could not afford the equipment, water,
  and chemicals needed to grow new crop varieties.

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Objectives

• Distinguish between traditional and modern
  agricultural techniques.
• Describe fertile soil.
• Describe the need for soil conservation.
• Explain the benefits and environmental impacts of
  pesticide use.
• Explain what is involved in integrated pest
  management.
• Explain how genetic engineering is used in
  agriculture.

Section 2
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Agriculture Traditional

• The basic processes of farming include plowing,
  fertilization, irrigation, and pest control.
• Traditionally, plows are pushed by the farmers or
  pulled by livestock. Plowing helps crops grow by
  mixing soil nutrients, loosening soil particles,
  and uprooting weeds. Organic fertilizers, such as
  manure, are used to enrich soil. While fields are
  irrigated by water flowing through ditches.
• These traditional techniques have been used since
  the earliest days of farming.

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Agriculture Modern

• In most industrialized countries, the basic
  processes of farming are now carried out using
  modern agricultural methods.
• Machinery powered by fossil fuels is now used to
  plow the soil and harvest crops. Synthetic
  chemical fertilizers have replaced manure and
  plant wastes to fertilize soil.
• A variety of overhead sprinklers and drip systems
  may be used for irrigation. And synthetic
  chemicals are used to kill pests.

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Fertile Soil The Living Earth

• Soil that can support the growth of healthy
  plants is called fertile soil.
• Topsoil is the surface layer of the soil, which
  is usually richer in organic matter than the
  subsoil is.
• Fertile topsoil is composed of living organisms,
  rock particles, water, air, and organic matter,
  such as dead or decomposing organisms. Several
  layers of soil lie under the topsoil. The bottom
  layer is bedrock, which is the solid rock from
  which most soil originally forms.

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Fertile Soil The Living Earth
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Fertile Soil The Living Earth

• Most soil forms when rock is broken down into
  smaller and smaller fragments by wind, water, and
  chemical weathering. Chemical weathering happens
  when the minerals in rock react chemically with
  substances to form new materials. Temperature
  changes and moisture can also cause rock to crack
  and break apart.
• It can take hundreds or even thousands of years
  for these geological processes to form a few
  centimeters of soil.

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Fertile Soil The Living Earth

• Other processes also help to produce fertile
  topsoil. For example, the rock particles supply
  mineral nutrients to the soil.
• Fungi and bacteria live in the soil, and they
  decompose dead plants as well as organic debris
  and add more nutrients to the soil.
• Earthworms, insects, and other small animals help
  plants grow by breaking up the soil and allowing
  air and water into it.

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Soil Erosion A Global Problem

• Erosion is a process in which the materials of
  the Earths surface are loosened, dissolved, or
  worn away and transported from one place to
  another by a natural agent, such as wind, water,
  ice, or gravity.
• In the U.S., about half of the original topsoil
  has been lost to erosion in the past 200 years.
• Without topsoil, crops cannot be grown. Yet,
  almost all farming methods increase the rate of
  soil erosion.

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Soil Erosion A Global Problem
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Land Degradation

• Land degradation happens when human activity or
  natural processes damage the land so that it can
  no longer support the local ecosystem. In areas
  with dry climates, desertification can occur.
• Desertification is the process by which human
  activities or climatic changes make arid or
  semiarid areas more desertlike.
• This process is causing some of our arable land
  to disappear.

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Soil Conservation

• There are many ways of protecting and managing
  topsoil and reducing erosion.
• Soil usually erodes downhill, and many soil
  conservation methods are designed to prevent
  downhill erosion.
• 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.

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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.
• Still, many areas of land that have hills are not
  suited to farming, but may be better used as
  forest or grazing land.

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Soil Conservation

• In 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.
• Although this method saves time and reduces soil
  erosion, it is not suited for all crops. Other
  disadvantages include soil that is too densely
  packed and lower crop yields over time.

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Enriching the Soil

• Soil was traditionally fertilized by adding
  organic matter that would decompose, adding
  nutrients to the soil and improving the soil
  texture.
• However, inorganic fertilizers that contain
  nitrogen, phosphorus, and potassium have changed
  farming methods. Without them, world food
  production would be less than half of what it is
  today.
• If erosion occurs in areas fertilized with
  inorganic materials, waterways may become
  polluted.

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Enriching the Soil

• Over the past 50 years, the use of such inorganic
  fertilizers has increased rapidly.

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Enriching the Soil

• A modern method of enhancing the soil is to use
  both organic and inorganic materials by adding
  compost and chemical fertilizers to the soil.
• Compost is a mixture of decomposing organic
  matter, such as manure and rotting plants, that
  is used as fertilizer and soil conditioner.
• Many cities and industries now compost yard and
  crop wastes. This compost is then sold to farmers
  and gardeners, and the process is saving costly
  land fill space.

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Salinization

• The accumulation of salts in the soil is known as
  salinization.
• Salinization is a major problem in places that
  have low rainfall and naturally salty soil.
• When water evaporates from irrigated land, salts
  are left behind.
• 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.

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Salinization

• The accumulation of salts in the soil is known as
  salinization.
• Salinization is a major problem in places that
  have low rainfall and naturally salty soil.
• When water evaporates from irrigated land, salts
  are left behind.
• 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.

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Pest Control

• Worldwide, pests destroy about one-third of the
  worlds potential food harvest.
• A pest is any organism that occurs where it is
  not wanted or that occurs in large enough numbers
  to cause economic damage.
• Humans try to control populations of many types
  of pests, including plants, fungi, insects, and
  microorganisms.

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Pesticides

• Many farmers rely on pesticides to produce their
  crops.
• A pesticide is a poison used to destroy pests,
  such as insects, rodents, or weeds examples
  include insecticides, rodenticides, and
  herbicides.
• Pesticides, however, can also harm beneficial
  plants and insects, wildlife, and even people.

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Pesticide Resistance

• Over time, spraying large amounts of pesticide to
  get rid of pests usually makes the pest problem
  worse.
• Pest populations may evolve resistance, the
  ability to survive exposure to a particular
  pesticide.
• More than 500 species of insects have developed
  resistance to pesticides since the 1940s.

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Human Health Concerns

• Pesticides are designed to kill organisms, so
  they 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.

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Pollution and Persistence

• The problem of pesticides harming people and
  other organisms is especially serious with
  pesticides that are persistent.
• A pesticide is persistent if it does not break
  down easily or quickly in the environment.
• Persistent pesticides do not break down into
  harmless chemicals, and they accumulate in the
  water and soil.
• Some pesticides have been banned in the United
  States for decades but can still be detected in
  the environment.

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Biological Pest Control

• Biological pest control is the use of certain
  organisms by humans to eliminate or control
  pests.
• 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 disruption of insect breeding

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Integrated Pest Management

• Integrated pest management is a modern method of
  controlling pests on crops.
• The goal of integrated pest management is 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 farming
  methods, biological pest control, and chemical
  pest control.

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Integrated Pest Management
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Integrated Pest Management

• Biological methods are the first methods used to
  control the pest. So, natural predators,
  pathogens, and parasites of the pest may be
  introduced.
• Cultivation controls, such as vacuuming insects
  off the plants, can also be used.
• As a last resort, small amounts of insecticides
  may be used. These insecticides are changed over
  time to reduce the ability of pests to evolve
  resistance.

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Engineering a Better Crop

• Genetic engineering is a technology in which the
  genome of a living cell is modified for medical
  or industrial use.
• Scientists may use genetic engineering 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.

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Engineering a Better Crop
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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, however, have not been
  fully tested for their environmental impacts.
• Some scientists warn that these products will
  cause problems in the future.

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Sustainable Agriculture

• Farming that conserves natural resources and
  helps keep the land productive indefinitely is
  called sustainable agriculture.
• Sustainable agriculture involves planting
  productive, pest-resistant crop varieties that
  require little energy, pesticides, fertilizer,
  and water.

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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.

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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.

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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.

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Food from Water
The North Atlantic cod fishery has collapsed
because too many fish were harvested over time.
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• 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.

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• 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 worlds oceans.

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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.

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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.

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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.

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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 50 years.
• Large livestock operations produce most of the
  meat that is consumed in developed countries.

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Livestock
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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
  digestsuch as beef.

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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.