Chapter 9: Food

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Chapter 9 Food Growing crops is easier than
building castles, yet there are many castles in
our world and not enough crops." . - Petak
Saeoung
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Discussion Why do you think it is so difficult
to provide adequate food for all of the worlds
people? Besides using chemical pesticides, how
might farmers keep insects from destroying crops?
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Feeding the People of the World
Ethopia - 1985 Thousands of people were
starving Lack of rain, soil degradation,
war Then rains came and washed millions of tons
of soil into the rivers. What People Eat Food
staples Asia - Rice China India - Grains
(noodles breads) Central America - Corn
(tortillas) Europe - Potatoes What could Irish
officials have done to prevent the potato famine
that occurred in Ireland in the 1800s? More
diverse crops
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3 Major nutrients in human foods 1.Carbohydrates
Found in breads, cereals, potatoes,
beans 2.Proteins Found in meat, fish,
eggs, dairy products, beans 3.Lipids /
Fats Found in butter, oils, fatty foods
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Malnutrition Condition caused by not consuming
enough necessary nutrients causes health
problems and possibly death 1 out of every 3
people on Earth are malnourished mostly the very
young or very old Example Malnutrition- due to
severe protein deficiency Most victims of these
diseases are Children Symptoms bloated abdomen,
diarrhea, loss of hair, liver damage, wide eyes,
thin body
If left untreated can cause mental retardation
and stunted growth can reverse with a balanced
diet
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• Why do people go hungry?
• The Worlds population is increasing fast than
  its food supply
• 2. Food supply is not equally divided
• 3. Difficulties in transporting food to those
• who need it
• 4. Droughts leading to crop failure and famine.
• Famine widespread food shortage that causes
  malnutrition in many people.
• How can we make a difference?

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THE GREEN REVOLUTION
Between 1950-1970 new varieties of grains new
farming techniques were introduced into Asian
Latin American countries - These new varieties
had a much greater Yield amount produced per
unit area.
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New grain did not grow well because it required
special fertilizers and more water than older
varieties. Subsistence Farmers grow only
enough food to feed their family could not
afford necessary chemicals Most of the increased
production came from Larger Farms that grow food
to be sold The pesticides and fertilizer's
polluted the environment.
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Agriculture and Soil Arable Land - fertile
land that can be plowed to grow crops Amount of
arable land is decreasing each year
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FERTILE SOIL Can support the rapid growth of
healthy plants Topsoil is loose surface layer of
soil in which the roots of most plants
grow Fertile topsoil is composed of rock
particles, water, air and organic matter (dead
plant animals and animal excrement) Living
organisms in soil (fungi, bacteria, earthworms)
break up the soil and let water and air into
it Most soil forms when Bedrock cracks and
breaks apart
It can take thousands of years to form a few
centimeters of soil
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Erosion Erosion is the wearing away of topsoil
by wind and water Topsoil is needed to grow
crops In the US, about 1/2 of the
topsoil has been lost to erosion in the past 200
years Ranked as one of the most serious
ecological problems we face Farming practices
that contribute to topsoil erosion Plowing Harve
sting Clearing of forests to produce lumber
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Desertification Process by which soil fertility
deteriorates and lands become desert
like Worldwide, an area the size of Nebraska
becomes desert each year Ex Sahel region of
northern Africa PROBLEMS several crops
planted/year Fallow periods shortened or
eliminated more animals put out to graze trees
and shrubs cut down
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• Soil Conservation
• 1. Contour Plowing
• plow across the slope of a hill
• tiny ridges help prevent soil from,
• washing down hill
• can also leave strips of vegetation running
• across hillside

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• 2. Use Organic Material instead of
• inorganic fertilizers
• - Compost
• Animal manure
• 3. No till farming
• - seeds of the next crop are planted in slits
  that are
• cut into the soil and through the remains of
  the
• previous crop.
• - Roots of old crop hold soil in place
• - As old crop decays, organic matter
• is added to the soil

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Sustainable Agriculture Low Input Farming does
not use a lot of energy, pesticides, fertilizer
or water 1.Organic Farming - Grow plants
without any synthetic pesticides or inorganic
fertilizers - Use manure compost - Alternate
crops to reduce pest populations 2. Aquaculture
(Fish-farming)
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• Salinization
• - Accumulation of Salt in the soil
• Plants cannot grow in salty soil
• Causes of Salinization
• 1. Water for irrigation is taken from rivers or
• groundwater which contain more salt than
• rainwater
• - When water evaporates it
• leaves salts behind
• 2. Irrigation causes level of groundwater to
• rise, drawn up by Capillary Action

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• Preventing Salinization
• Line irrigation canals to prevent water from
• seeping into the soil and raising the
  groundwater level
• 2. Water the soil heavily to wash out salts
  before seeds are planted
• 3. Plant salt-tolerant crops which absorb salts
  from soil
• 4. Plant salt-tolerant trees
• - Help to reclaim the soil and prevent
  evaporation of water thereby slowing the upward
  movement of groundwater
• - Roots of trees penetrate the soil and allow
  rainwater to sink in and wash out the salts

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• PEST CONTROL
• - Worldwide, pests destroy 1/3 of all
  crops.
• Wild plants have more protection from pests than
  crop
• plants.
• 1. Grow scattered apart
• 2. Pest predators
• 3. Evolved defenses (poisonous plant fluids)

3 Main Types Pesticides 1. Chlorinated
hydrocarbons 2. Organophosphates 3. Carbamates
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• Drawbacks of Pesticides
• 1. Health Concerns
• - high Cancer Risk
• accidental chemical leaks in factories
• 2. Pollution and Persistence
• persistent pesticides do not break down
• rapidly into harmless chemicals they
• accumulate in the water and soil

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DDT used in 1940s to kill mosquitoes and lice 1.
DDT accumulated in the water 2. Fish absorbed
DDT 3. Birds ate the fish 4. Birds layed eggs
with thin shells that broke when the
birds sat on them 5. Penguins, pelicans,
peregrine falcons, and eagles were
endangered and even wiped out as a
result DDT was eventually banned in the U.S.
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• Resistance
• Ability to tolerate a particular pesticide
• 1. A few insects contain a gene that protects
  them from the pesticide.
• 2. Those insects survive and pass that gene onto
  their offspring.
• 3. The resistant insects continue to reproduce
  while the others die off.
• More than 500 species of insects have developed
  resistance to pesticides since the 1940s.

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• Biological Pest Control
• 1. Predators and Pathogens
• Release a natural predator, parasite, or
• pathogen into the area where the pest lives

Parasitoids. This wasp is laying its egg inside an aphid where its young will develop. Parasitoid immatures develop on or inside a host, killing it as they mature. They emerge as adults and continue the cycle. Predators. Lady beetles are well-known examples of predatory insects. A predator consumes many prey during its lifetime. The predators listed in this guide feed on insects and mites. Pathogens. This nematode is just one example of a pathogen which may kill its host. Other pathogens include bacteria, viruses, fungi and protozoa. This section also includes antagonists which control plant diseases. Weed Feeders. Weeds can be attacked by arthropods, vertebrates, and pathogens. This weevil feeds only on one particular type of weed called purple loosestrife.
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2. Plant defenses - Crossbreed plant
varieties to produce crops with their own
defenses such as a tougher skin
3. Chemicals from Plants
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• 4. Disrupt Insect Breeding
• - Treat crops with Pheromones (insect hormones)
• Treat males with x-rays, make them sterile, then
  
• release them
• After mating, females will
• produce eggs that do not
• develop

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• 5. Home remedies
• A. Cockroaches
• - Put honey in the bottom of a jar and set it
  upright
• Line the cracks where roaches enter your home
  with bay leaves the smell of bay leaves repels
  roaches
• B. Ants
• - Squeeze fresh lemon or lime juice into the
  holes or cracks and leave the peels where you've
  seen ants
• Scatter mint around your shelves and cabinets
• C. Fleas and Ticks
• - Feed the animal brewer's yeast or vitamin B
• - Spray animal with a mixture of rosemary and
  water

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