Transcript Food and Agriculture

Food and Agriculture
Land Use
• 11% of the earth’s land is used in agricultural
production
– Less land cultivated in NA now than 100 years
ago
Types of Food Production
1. Traditional subsistence agriculture
–
mostly human and animal labor
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Produces only enough crops for a family’s survival
Africa, Asia, South America
Types of Food Production
2. Industrialized agriculture (high input
agriculture)
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Large amount of fossil fuel energy, water, fertilizers
and pesticides to produce large quantities of
monocultures
Example: Plantation agriculture
– Used in tropical developing nations
– Cash crops grown for export
» May provide non-food products (latex)
» Provide products that do not make up primary nutrition
(tea, coffee)
Agroecosystems
• Ecosystem created by agricultural
practices
– characterized by low
• Genetic diversity
• Species diversity
• Habitat diversity
Agroecosystems
Differ from natural ecosystems in five major ways:
1. Farming attempts to stop ecological succession
2. Species diversity is low
• Monoculture ↓ soil fertility
3. Plant species (crops) in an orderly fashion
–
pest control more difficult
4. Simple food chains
5. Plowing
• ↑ erosion
• Nutrient loss
Farm Numbers
Number of People Fed
Annually By One Farmer
Food Supply
• 15 to 20 species provide vast majority (90%) of
man’s food needs
– Wheat, rice, corn, potatoes, barley
• Wheat and rice supply ~60% of human caloric
intake
– 90% of grain grown in NA is used to feed
livestock
Meat Sources
• 20% of the richest countries consume 80% of
the world’s meat
• About 90% of the grain grown in the United
States is used for animal feed
• 16 lbs of grain → 1 lb of meat
World Food Supply and the
Environment
• Enough food, unevenly distributed
– 815 million people do not have enough to eat
• Parts of Africa, southeast Asia
– In richest countries, 11 million do not have
enough to eat
• Food production depends upon favorable
environmental conditions
Food Distribution
• Food is not distributed equally due to:
– Soil and climate differences
– Political and economic power
– Average per capita income throughout the world
Malnutrition/Famines
• Malnutrition
– Undernutrition
– Overnutrition
• Famine
– Environmental conditions are immediate trigger, but politics and
economics are often underlying problems.
• Famine conditions
– Major droughts
– Population sizes
– Massive immigration
– Floods
– Wars
-- Political instability
-- Land Seizures
-- Distribution breakdown
-- Chaos in economy
Risk of Inadequate Nutrition
Undernutrition Problems
• Iron deficiency
– Most common
– Leads to anemia
• Red meat, eggs, legumes, and green vegetables are all
good sources of iron.
• Vitamin A deficiencies
– Can cause blindness
Obesity
• Most common dietary problem in wealthy
countries
– According to U.S. Surgeon General:
• 62% of Americans are overweight.
– 33% are obese.
Land Use and Degradation
• Overgrazing and soil erosion
• Eliminates millions of acres a year
• Desertification-degrading once fertile land
into desert
• Surface runoff
• Dry surface reflects heat, changing wind patterns
Global Soil Degradation
Mechanisms of Erosion
• Wind and water are erosive forces
– Intensive farming practices:
• Salinization
• Waterlogging
– Impairs root growth,
roots cannot get oxygen
• No crop rotation
• Removal of windbreaks
• Continued monocultures
Alternatives to Industrial Farming
Methods
Sustainable Agriculture
• Through soil conservation
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Intercropping
Crop rotation
Agroforestry
Contour Plowing
Soil Conservation Cont.
• Providing Ground
Cover
– No till agriculture
– Plant cover crops
• Improved irrigation
and utilization of water
– Drip irrigation
New vs. Old
Agriculture
Methods to Increase Food
Supply
• Food distribution modification
– Teach locals
• In the 1960s:
– Green Revolution-increased yields per unit of area of
cropland
• Mechanization
– Monocultures of selectively bred or genetically engineered high yield
variety of key crops (rice, corn, wheat)
» Corn yields jumped from 25 bushels per acre to 130 per acre in
last century.
• Using high inputs of fertilizer, pesticides, and water on crops to
produce high yields
• Increasing the intensity and frequency of cropping
Genetic Engineering
• Genetically Modified Organisms (GMO’s)
– Crops resistant to drought, frost, diseases, pests,
etc.
– Animals that grow faster, gain weight on less
food, produce more milk, etc.
– Estimated at least 70% of all processed foods in
NA contain transgenic products.
Is Genetic Engineering Safe ?
• Environmental and consumer groups have
campaigned against transgenic organisms.
– “Frankenfoods”
– Opponents fear traits could spread to wild
varieties
– U.S. Food and Drug Administration declined to
require labeling of foods containing GMO’s.
• New varieties are “substantially equivalent” to related
traditionally-bred varieties.
How Would You
Vote?
• Do the advantages of
genetically engineered
foods outweigh their
disadvantages?
• Should labeling of
GMOs be required?
Increasing Food Supply:
Producing More Meat
• ½ of the world’s meat is produced by
livestock grazing on grass.
• ½ half is produced under factory-like
conditions (feedlots).
– Concentrated animal feeding operations (CAFOs)
• High density, confined or allowed very little moving
room
– A CAFO may contain as many as 2500 hogs or 55,000
turkeys in a single building
Trade-Offs
Animal Feedlots
Advantages
Increased meat
production
Higher profits
Less land use
Reduced overgrazing
Reduced soil
erosion
Help protect
biodiversity
Disadvantages
Need large inputs
of grain, fish
meal, water, and
fossil fuels
Concentrate
animal wastes
that can pollute
water
Antibiotics can
increase genetic
resistance to
microbes in
humans
Fig. 13-21, p. 289
Sustainable Animal Farming
• Free-range
• Organic
• Smaller scale farms
Buy Local!
• The average American foodstuff travels an
estimated 1500 miles before being consumed.
Catching and Raising More
Fish
• Fisheries
– third major food-producing system
• ~55% of annual commercial catch from ocean
• ~45% from use of aquaculture to raise marine and
freshwater fish
Fishing methods
Catching and Raising More
Fish
– Commercial fish amounts have been declining
since 1980
• Overfishing
– Tragedy of the commons
– Bycatch
Raising More Fish
Aquaculture: Aquatic Feedlots
• Raising large numbers of fish and shellfish in
ponds and cages in a controlled environment
and harvesting them in captivity.
Trade-Offs
Aquaculture
Advantages
High efficiency
High yield in
small volume
of water
Can reduce
overharvesting
of conventional
fisheries
Low fuel use
High profits
Profits not tied
to price of oil
Disadvantages
Needs large inputs
of land, feed, and
water
Large waste
output
Destroys
mangrove forests
and estuaries
Uses grain to feed
some species
Dense populations
vulnerable to
disease
Tanks too
contaminated to
use after about 5
years
Solutions
Managing Fisheries
Fishery Regulations
Set catch limits well below the maximum
sustainable yield
Bycatch
Use wide-meshed nets to allow escape of
smaller fish
Improve monitoring and enforcement
of regulations
Use net escape devices for seabirds and
sea turtles
Economic Approaches
Sharply reduce or eliminate fishing subsidies
Ban throwing edible and marketable fish back
into the sea
Charge fees for harvesting fish and shellfish
from publicly owned offshore waters
Aquaculture
Restrict coastal locations for fish farms
Certify sustainable fisheries
Control pollution more strictly
Protected areas
Establish no-fishing areas
Depend more on herbivorous fish species
Establish more marine protected areas
Nonnative Invasions
Kill organisms in ship ballast water
Rely more on integrated coastal
management
Filter organisms from ship ballast water
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
Dump ballast water far at sea and replace with
Deep-sea water