Chapter 9: FOOD

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Chapter 9 FOOD

• In simplest terms, agriculture is an effort by
  man to move beyond the limits set by nature.

Lester R. Brown President, Worldwatch Institute
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9.1 Feeding the People of the World

• Ethiopa, 1985 people were starving (lack of
  rain, soil degradation, war) when rain came, it
  washed away millions of tons of soil into the
  rivers resulted in 6,000 sq. mi. of desert
• Efforts by us to feed more people in this world
  are causing this environmental change, making it
  more difficult to feed all the people

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What People Eat

• We must consume organic compounds in order to
  survive (carbohydrates, proteins, lipids) we
  also need vitamins and minerals to help our
  bodies function properly
• Food is used as a source of energy and for
  building and maintaining our bodies lack of
  enough food will result in sickness or death
  starving people die from disease that our bodies
  cannot fight off malnutrition is a result of not
  eating enough of the necessary nutrients

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Why People go Hungry

• Increasing populations requires more food food
  production is increasing but amount of food per
  person is not increasing
• It is not equally distributed throughout the
  world wealthy people have an abundance poor
  people have much less than they need
• Malnutrition occurs everywhere in the world
  starvation results when food cannot be
  transported to where it is needed (transportation
  lines break down, wars)
• Droughts can contribute to starvation as well
  combined with war or a break in transportation
  can result in a famine (food shortages in a wide
  spread area)

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The Green Revolution

• In an effort to increase crop yields, new
  varieties of grain and farming methods were
  introduced between 1950 and 1970, resulting in a
  much greater yield
• Problems need the right kind of fertilizers and
  pesticides, and irrigation water
• Subsistence farmers only grow enough for their
  families and cant afford the proper tools
  therefore, only large scale farms grow food to be
  sold (they are at their max now) large use of
  fertilizers and pesticides are polluting the
  environment machinery uses a large amount of
  energy

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Political Changes

• Making peace in war-torn countries is essential
  toward supplying its people with enough food
• Donated food can then be distributed more
  effectively
• Sustainable farming techniques can be learned

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9.2 Agriculture and Soil

• Earth has a limited amount of arable land
  (fertile) to grow crops decreases every year
  (1/5 from 1985 to 2000)
• 371 million acres of farmland will be covered by
  houses and industry 334 million acres will
  become unusable for farming because soil will be
  damaged
• This shortage of fertile land threatens our
  ability to feed the human population

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Farming

• Plowing, fertilization, irrigation and pest
  control began with the earliest farmers animals
  or people pulled plows through the soil (mixes up
  the nutrients, loosens soil and uproots weeds)
• Organic fertilizers (manure) enriched soil
  digging ditches supplied water weeds were dug up
  by hand still used today in many places
• Large farms in industrialized countries use
  machinery (to plow and harvest) synthetic
  fertilizers are used to enrich soil overhead
  drips/ sprinkles for irrigations chemicals kill
  pests

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Fertile Soil

• Soil that can support the rapid growth of healthy
  plants is called fertile soil most root in
  topsoil (loose soil comprised of rock particles,
  water, air and organic matter)
• Living organisms (earthworms, insects and other
  small animals) play an important role in breaking
  up the soil also the decomposers (fungi,
  bacteria, microorganisms) when they break down
  detritus
• It can take thousands of years to form a few
  centimeters of soil

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Topsoil Erosion A Global Problem

• Soil that has been formed is being lost to
  erosion
• In US, about ½ of the topsoil has been lost to
  erosion in the past 200 years worldwide, 11 of
  the soil has been eroded in the past 45 years
• Soil erosion is ranked as one of the most serious
  ecological problems we face today
• Some farming techniques today contribute to the
  erosion (blowing wind and rain washing it away)
• Harvesting removes roots and other organic matter
  that holds the soil together clearing forests
  for lumber water runoff carries away the soil

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Desertification

• Loss of topsoil, especially in dry areas, is
  severe if it deteriorates so much the land
  becomes desert-like (desertification) worldwide
  an area the size of Nebraska becomes desert every
  year
• Ex In Northern Africa, if the appropriate
  method of rotating the crops and grazing their
  animals were observed, the land would adequately
  support the people of that region however,
  today, increased overuse of the land and large
  numbers of grazing animals have left the land
  barren. Resulting in desert rather than
  productive farm/grazing land

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Soil Conservation

• There are many ways to conserve topsoil and
  reduce erosion pay attention to the slope of
  the land when planting, contour plowing (plowing
  across the slope of the hill), leaving strips of
  vegetation running across the hillside, not
  farming in an area where it is very hilly
• Use organic material rather than inorganic
  fertilizers (restores soil) compost or manure
• Change the way farmland is plowedrather that
  plowing under, plant new crops through the
  remains of the old plants allowing less erosion
  and natural organic matter to be added to the soil

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Sustainable Agriculture

• How can we feed the worlds population without
  depleting the worlds resources?
• Low-input farming farming without using a lot
  of energy, pesticides, fertilizers and water
• Ex organic farming farming without the use of
  synthetic materials, use manure, compost and keep
  the land planted at all times (reducing erosion),
  alternating crops
• Aquaculture fish farming or raising fish in
  artificial environments

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Preventing Salinization

• Salinization is the accumulation of salt in the
  soil salt is in the soil naturally, but when it
  is irrigated with water from rivers or
  groundwater, it builds up and makes the land
  unusable rainwater contains less salt than
  groundwater
• Ways to slow soil salinization irrigation
  canals, water soil heavily prior to planting
  seeds, plant salt tolerant crops or trees to
  reclaim the land (shade trees will reduce
  evaporation from the soil surface fallen leaves
  add organic matter to the soil)
• Total restoration of the land takes decades

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Old and New Foods

• Researchers are investigating ancient plants and
  looking at new varieties of plants
• Looking for plants betters adapted to different
  climates and produce high yields without large
  amounts of fertilizers, pesticides and water
• Studying plants that have not been widely used
  for food in the past but may be useful
• Ex Amaranth sacred food of the Aztecs and
  Glasswort can be grown in saline soil

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9.3 Pest Control

• In North America, 13 of all crops are destroyed
  by insects tropical climates enough greater
  damage Kenya lose 25 of their crops from
  insects worldwide, 1/3 of the worlds potential
  food harvest is destroyed
• Wild plants have more protections from pests than
  do crop plants wild plants are scattered,
  therefore, harder to find, have evolved defenses
  and have pest predators living in or around them
  crops plants are all in one location, a one-stop
  food source
• Over the last 50 years, many new chenical
  pesticides have been developed and farmers have
  begun to rely on them to protect their crops

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Drawbacks of Pesticides

• Unfortunately, the new pesticides affect a lot
  more than just the pests that they were designed
  to kill
• They can also harm people and wildlife

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Health Concerns

• Many pesticides can cause people to get sick
• Ex California has seen an increase in cancer
  rates among children in areas which grow fruits
  and vegetables with high pesticide use
• Workers in pesticide factories may become ill, as
  well as the people living near these factories,
  from accidental chemical leaks

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Pollution and Persistence

• Pesticides can become problematic for humans and
  wildlife because they are persistent (dont break
  down rapidly into harmless substances when they
  enter the environment), they accumulate in the
  water and soil
• Ex DDT used in the 1940s to kill mosquitoes
  (malaria, lice that spread typhus) DDT is very
  persistent, gradually accumulates in bodies of
  water, absorbed by fish, and then eaten by birds
  resulted in increased levels of DDT in bodies
  eggs were so thin they broke when sat on
  (penguins, pelicans, peregrine falcons, eagles)
  many became endangered
• DDT banned in U.S. but continues to remain in
  the environment

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Pesticide Resistance

• Spraying large amounts of pesticides is NOT the
  most effective way to get rid of pests it
  usually makes it worse pests evolve resistance
  (ability to tolerate a particular pesticide)
• How? Some of the insects have a gene that
  protects them from a pesticide they go on to
  reproduce, passing on that resistance gene to
  their offspring
• More than 500 species of insects have developed
  resistance to pesticides since the 1940s

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Biological Pest Control

• Because resistance evolves so rapidly, farmers
  and pest-control companies are using fewer
  pesticides
• Turning to biological pest control (using living
  organisms or naturally produced chemicals to
  control pests
• Generally do no harm anything but the particular
  pest it is designed to control, resistance takes
  longer to evolve

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Predators and Pathogens

• Releasing a natural predator or parasite is one
  method of biological control
• Pathogens (organisms causing disease) is another
  method
• Ex Bacillus thuringensis (bacterium) kills
  larvae (caterpillars of moths and butterflies)

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Plant Defenses

• Cross breeding some plant varieties to produce
  crops that have their own defenses
• Ex production of chemical compounds that repel
  pests tougher skin

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Chemicals from Plants

• Make use of plants defense chemicals
• Ex extracting chemicals from the chrysanthemum
  and sell it as a pesticide they are
  biodegradeable

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Disrupting Insect Breeding

• Pheromones (chemicals produced by an organism
  that affect the behavior of another) are also
  used
• Ex female moths find mates by releasing
  pheromones that attract males, farmers treat
  crops with those pheromones to confuse the males
  (interferes with mating)
• Another example treat male insects with xrays,
  making them sterile when they mate, eggs do not
  get fertilized

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Thank You!