Transcript Day 6

GEOG 101
Fall 2013
Jeff Lewis
Agriculture
Learning Outcomes:
• At the end of this lecture, you should be able to:
• State the importance of soils for agriculture and in
supporting plant growth
• Outline the historical development of agriculture and the
transition to industrialized agriculture
• Identify the causes of soil erosion and soil degradation,
and explain the basic principles of soil conservation
• Explain the challenge of feeding a growing human
population
• Evaluate sustainable agriculture
• Describe the science behind genetically modified food and
evaluate controversies over genetically modified food 3-2
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Why Should You Care About Food Resources
Three major reasons
•Food required for healthy & productive life
•1 billion people do not get enough food
•Food production large environmental impact
- 38% of world’s ice free land in agriculture
- 70% of freshwater used for agriculture
- 60% of water pollution
- 25% of human greenhouse gases
Most of
Canada's
wasted food
dumped
from homes
• $27B worth of
food wasted across
the country every
year, research
group says
3-4
7 ways to reduce household food waste
1. Take stock before you shop
2. Plan your meals
3. Be smart about expiration dates
4. Don't assume you need to buy in bulk
5. Learn the art of pre-portioning
6. Use more of your fruits and veggies
7. Think twice before tossing overripe fruits and veggies
http://www.cbc.ca/news/canada/story/2012/10/01/f-food-waste-reduction-tips.html
Soil
• a complex plant-supporting
system consisting of:
- disintegrated rock
- organic matter
- water
- gases
- nutrients
- microorganisms
Soil cannot be considered a renewable resource as it
takes 500 to 1000 years to produce 2.5 cm of topsoil
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Percent of land use for growing crops
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Food Choices
•
There are fewer than two dozen species of major food sources.
They all share three characteristics:
1. High yield
- High production per unit area of land. Essential to
subsistence farmers dependant on small parcels of land
2. High food value
- Staple foods have high total calories and essential nutrients:
carbohydrates, proteins, fats and vitamins
- Most subsistence farmers plant a grain or tuber crop for
caloric intake and then vegetables and fruit for additional
nutrients
3. Storage ability
- Most foods are harvested at a certain time of year and must
last until the next harvest
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Food Choices
• Top five global crops:
1. Potato
2. Cassava (Manioc)
3. Wheat
4. Rice
5. Corn (Maize)
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Food Choices
• Efficiency
- 90% of human food comes from plants
• Developing World
- are more efficient than developed world because they
rely on the lowest trophic level in the energy pyramid
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Food Choices
• Efficiency
- 90% of human food comes from plants
• Developed World
- most agriculture aimed at livestock and the crops that
feed them
- vast amounts of food energy is used in producing
animal protein
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Consumption of animal products is growing
FIGURE 8.15
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Our food choices are also energy choices
• 90% of energy is lost
every time energy
moves from one trophic
level to the next
• The lower on the food
chain from which we
take our food sources,
the more people the
Earth can support
FIGURE 8.17
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Environmental ramifications of eating meat
• Land and water are needed to raise food for livestock
• Producing eggs and chicken meat requires the least
space and water; beef requires the most
FIGURE 8.18
When we choose what to eat, we also choose how we use resources
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8-15
The Evolution of Agriculture
• Agriculture led to:
- stable food source
- urban centres
- specialization
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Systems of Agricultural Production
• Subsistence Agriculture: basic needs are met with a
small surplus for trade or store
- most widespread agricultural system in the world
• Three Subsistence Agricultural Methods:
1. Intensive Subsistence Farming: supports dense
populations as it produces relatively high yields per
unit of land
2. Shifting cultivation: supports small populations,
requires large areas
3. Nomadic herding: supports very small populations,
based on seasonal migration
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Systems of Agricultural Production
• Industrial Revolution
- Mechanization enabled farmers to specialize and mass
produce
- led to commercial agricultural systems that
dominated regions
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Systems of Agricultural Production
Wheat
Dairy
General
Range
Cotton
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Systems of Agricultural Production
• Industrial Agriculture: emphasize specialized
production of crops and livestock to sell
- can produce enough food to feed many other people
• Production efficiency is achieved in two ways:
1. improved inputs such as seeds, irrigation, fertilizers
and pesticides promote higher yield
2. Specialized machinery speeds up production and
requires fewer people, uses fossil fuels
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Fertilizers boost yields but can be overapplied
• Fertilizer = substances that contain essential nutrients
• Inorganic fertilizers = mined or synthetically
manufactured mineral supplements
• Organic fertilizers = the remains or wastes of organisms
- manure, crop residues, fresh vegetation
- Compost = produced when decomposers break down
organic matter
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Fertilizers boost yields but can be overapplied
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Soil degradation: We lose 5-7 million
hectares of productive cropland annually
FIGURE 7.6
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Soil degradation has many causes
• Soil degradation results
from deforestation,
agriculture and
overgrazing
• Over the past 50 years,
soil degradation has
reduced global grain
production by 13%
FIGURE 7.7
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Agriculture and the Environment
• Increased demand for food has led to an expansion of
cropland and techniques that produce higher yields
• This has led to worldwide environmental degradation
• The main causes of degradation are:
- Soil Erosion
- Desertification
- Overgrazing
- Salinization and Waterlogging
- Groundwater Depletion and Contamination
- Surface Water Impacts
- Simplification and Substitution
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Agriculture and the Environment
• Key is increased soil conservation
• Systems to reduce soil erosion:
- Intercropping
- Terracing
- Contour planting and strip cropping
- Crop rotation
- Reduce tillage
- Remove land from agriculture
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We are producing more food per person
FIGURE 8.1
• Food security = the guarantee of an adequate, reliable,
and available food supply to all people at all times
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We face both too little and too much food
• Undernourishment = people receive less than 90% of
their daily caloric needs
- Mainly in developing countries
• Malnutrition = a shortage of nutrients the body needs
- The diet lacks adequate vitamins and minerals
• Overnutrition = receiving too many calories each day
- In Canada, 48% of adults exceed their healthy weight
and ~25% are obese
- Between 1981 and 2009, measured obesity doubled
Obesity in Canada: A joint report from the Public Health Agency of Canada and the Canadian
Institute for Health Information (2011)
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New Horizons in World Agriculture
• The Green Revolution: the use of new technology, crop
varieties and farming practices introduced to developing
countries
• the Green Revolution led to a tripling of grain yields
between 1950 and 1990
• From 1900 to 2000, humans expanded the world’s total
cultivated area by 33% and energy inputs increased by 80
times:
- Synthetic fertilizers
- Chemical pesticides
- Irrigation
- Heavy equipment
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New Horizons in World Agriculture
• Shortcomings of the Green Revolution
- limited participation by small, subsistence farmers
- increased mechanization and farm size
- increased commercialization
- loss of genetic diversity (monocultures)
- reduction in soil fertility and increased erosion potential
- soil damage and water resource depletion from
increased irrigation
- many regions initially bypassed by the Green
Revolution
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Pests and pollinators
• Pest = any organism that damages valuable crops
• Weed = any plant that competes with crops
FIGURE 8.4
Armyworms easily defoliate monocultures
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Many thousands of chemical pesticides
have been developed
• Pesticides = poisons that target pest organisms
- Insecticides = target insects
- Herbicides = target plants
- Fungicides = target fungi
• 91% of pesticide sales are for agricultural purposes
• 85% of pesticides sold in Canada are herbidices
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Pests evolve resistance to pesticides
• Resistance is passed through their genes to insect
offspring
• Pesticides stop being effective
• Evolutionary arms race: chemists increase chemical
toxicity to compete with resistant pests
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Biological control pits one organism
against another
• Biological control (Biocontrol) = uses a pest’s natural
predators to control the pest
FIGURE 8.6
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Biocontrol agents themselves may become
pests
• No one can predict the effects of an introduced species
• The agent may have “nontarget” effects on the
environment and surrounding economies
• Removing a biocontrol agent is harder than halting
pesticide use
- Due to potential problems, proposed biocontrol use
must be carefully planned and regulated
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Integrated Pest Management (IPM)
combines biocontrol and chemical methods
• IPM uses multiple techniques to suppress pests
- Biocontrol
- Chemicals, when necessary
- Population monitoring
- Habitat alteration
- Crop rotation and transgenic crops
- Alternative tillage methods
- Mechanical pest removal
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We depend on insects to pollinate crops
• Pollination = male plant sex cells fertilize female sex
cells
• Value of insect pollination services in Canada is $1.2
billion
• Animals pollinate
75% of the world’s
staple crops and 90%
of all non-food
flowering plants.
FIGURE 8.8
Flowers are evolutionary adaptations to attract pollinators
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Conservation of pollinators is vital
• Beekeepers are hired regularly to bring honeybee colonies to
crops for pollination
• To conserve bees:
- Reduce or eliminate pesticide use
http://www.cbc.ca/news/canada/huge-honey-bee-losses-across-canada-dashhopes-of-upturn-1.1699198
http://www.cbc.ca/news/canada/pesticide-linked-to-bee-deaths-to-get-tighterregulation-1.1829858
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Crossbreeding and Genetic Engineering
Early efforts at crop improvement
- Crossbreeding, or artificial selection
- Many current crops produced this way
- Requires long periods of time
Genetic engineering
- Adding, removing or changing DNA directly
- produces genetically modified organisms (GMOs)
- Similar to crossbreeding, but can use new genes
- Much faster than crossbreeding
- Can yield improvements quickly, but controversial
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Genetic engineering is like, and unlike,
traditional agricultural breeding
• Scientific techniques to develop more productive crops and
livestock has been around for more than a century
• Similar:
- Both alter gene pools for preferred characteristics
- Both apply to plants and animals
• Different:
- Traditional breeding uses genes from the same species
- Selective breeding deals with whole organisms, not just
genes
- In traditional breeding, genes come together on their own
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weighing
the issues
GM foods and you
Do you think you have ever eaten a food product that
contained genetically modified organisms?
• As much as 70% of the food products on shelves in
North American grocery stores contain at least some
GM ingredients.
• Check your kitchen cupboards for any foods that
contain products or ingredients made from corn, soy,
or canola.
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Biotechnology is transforming the products
around us
FIGURE 8.12
2006: Globally, GM foods grew on 106 million hectares of
farmland, producing $6.15 billion worth of crops
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Biotechnology
• Concerns of transgenic crops
- herbicide resistant crops will encourage the use of
herbicides (kills non-target species and pollutes soil/water)
- crops might transfer their herbicide tolerance to closely
related weeds (super weeds)
- built-in pesticides will promote rapid evolution of resistant
pests (super pests)
- may permanently alter wild plants and reduce diversity
- genetically engineered seeds add to production costs
- only a small group of N.A. and European companies will
control most of the worlds certified seed supply
- health concerns have led to a debate about labelling
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Precautionary principle
• Supporters make the following points:
- GM crops pose no ill health effects
- They benefit the environment by using less herbicides
- Herbicide-resistant crops encourage no-till farming
- GM crops reduce carbon emissions by needing fewer
fuel-burning tractors and sequestering carbon in the
soil by no-till farming
• Critics argue that we should adopt the precautionary
principle = don’t do any new action until it is understood
• CBC
• Guardian
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Debate over GM foods involves more than
science
• Ethical issues play a large role
- People don’t like “tinkering” with “natural” foods
- With increasing use, people are forced to use GM
products, or go to special effort to avoid them
- Multinational corporations threaten the small farmer
- Research is funded by corporations that will profit if
GM foods are approved for use
- Crops that benefit small, poor farmers are not widely
commercialized
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Sustainable Agriculture
• Sustainable agriculture = does not deplete soil, pollute
water, or decrease genetic diversity
• Low-input agriculture = uses smaller amounts of pesticide,
fertilizers, growth hormones, water, and fossil fuel energy
than industrial agriculture
• Organic agriculture = Uses no synthetic fertilizers,
insecticides, fungicides, or herbicides
- Relies on biological approaches (composting and
biocontrol)
- 2009: Organic Products Regulations
- Multi-ingredient products must be 95% organic
- Organic certification logo
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The benefits of organic farming
• For farmers:
- Lower input costs, enhanced income from highervalue products, reduced chemical costs and pollution
- Obstacles include the risks and costs of switching to
new farming methods and less market infrastructure
• For consumers:
- Concern about pesticide’s health risks
- A desire to improve environmental quality
- Obstacles include the added expense and less
aesthetically appealing appearance of the product
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Locally supported agriculture is growing
• The average food product sold in North America travels
at least 2300 km between the farm and the shelf, and is
often chemically treated to preserve freshness and colour.
• Farmers and consumers are supporting local agriculture
- Fresh, local produce in season
• Community-supported agriculture = consumers pay
farmers in advance for a share of their yield
- Consumers get fresh food
- Farmers get a guaranteed income
• Community gardens = areas where residents can grow
their own food
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Summary
• Intensive commercial agriculture has substantial
negative environmental impacts
• If our planet will be able to support 9 billion humans,
we must shift to sustainable agriculture
- Biological pest control
- Organic agriculture
- Pollinator protection
- Preservation of native crop diversity
- Careful, responsible genetic modification of food
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