Agriculture and Food
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Outline
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Nutrition and Food Supplies
Soil
 Structure
 Erosion
Agricultural Resources
 Water
 Energy
Genetic Engineering
Sustainable Agriculture
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Subsistence agriculture
Commercial agriculture
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
NUTRITION AND FOOD SUPPLIES
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World food supplies have more than kept up
with human population growth over the past
two centuries.
 1950 - 2.5 billion people - average daily
diet was less than 2,000 calories/person.
 2001- 6.0 billion people - world food supply
can provide more than 2,500
calories/person.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Nutrition
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The most common dietary problem in wealthy
countries is over-nutrition.
 In NA and Europe, average daily caloric
intake is 3,500 calories.
Sub-Saharan Africa has not kept food
production up to pace of population growth.
Collapse of Soviet Union also led to significant
collapse in food production.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Chronic Hunger and Food Security
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About 1 in 5 people in the developing world
are considered chronically hungry.
 200 million children
- Can lead to permanently stunted growth,
mental retardation, and other
developmental disorders.
 Poverty is the greatest threat to food
security (The ability to obtain sufficient
food on a daily basis).
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Chronic Hunger and Food Security
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Essential Nutrients
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Malnourishment - Nutritional imbalance
caused by a lack of specific dietary
components.
 In poorer countries, people often cannot
afford to purchase an adequate variety of
foods, including meats and vegetables.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Risk of Inadequate Nutrition
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Famines
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Famines are characterized by large-scale food
shortages, massive starvation, social
disruption, and economic chaos.
 Mass migrations often occur because
productive capacity has been sacrificed.
 Environmental conditions are immediate
trigger, but politics and economics are often
underlying problems.
- Arbitrary political boundaries block historic
access to refuge areas.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Famines
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Aid policies of rich countries often serve to
distribute surplus commodities and produce
feeling of generosity.
 Food camps have serious drawbacks:
- Stress and crowding
- Lack of sanitation
- Close contact to epidemic diseases
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
MAJOR FOOD SOURCES
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Three crops deliver majority of world’s
nutrients:
 Wheat, Rice and Corn
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Potatoes, barley, oats and rye are
staples in cool, moist climates.
Cassava, sweet potatoes, and other
roots and tubers are staples in warm wet
climates.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Meat and Milk
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Meat and Milk distribution highly inequitable.
 Core makes up 20% of world population,
but consumes 80% of meat and milk.
 60% of production occurs in lesser
developed countries.
 90% of grain grown in NA is used to feed
livestock.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Meat
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Every 16 kg of grain and soybeans fed to
beef cattle in feedlots produce about 1 kg of
edible beef.
 If we ate the grain directly, we would obtain
21x more calories and 8x more protein
than we get from eating the beef.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Seafood
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Seafood is an important protein source.
Since 1989, 13/17 major fisheries have
declined or become commercially inviable.
Between 1970-1990, number and average
vessel size of world fishing fleet doubled.
 Now have twice the capacity needed to
extract total annual sustainable harvest.
- Catching $70 billion cost $124 billion.
 1/4 animals considered by-catch.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
SOIL: A RENEWABLE RESOURCE
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Soil - A complex mixture of weathered
minerals, partially decomposed organic
materials, and a host of living organisms.
 At least 20,000 different soil types in the US.
- Vary due to influences of parent material,
time, topography, climate, and organisms.
 Can be replenished and renewed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Ways we use and abuse soils
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Approximately 11% of the earth’s land area is
currently in agricultural production.
 Up to four times as much could potentially
be converted to agricultural use.
- Much of this additional land suffers from
constraints.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Degradation
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Land Resources
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In developed countries, 95% of recent
agricultural growth has been from altered
agricultural practices (pesticides - fertilizer).
 Less land cultivated in NA now than 100
years ago.
Many developing countries are reaching limit
of lands that can be exploited for agriculture
without unacceptable social and
environmental costs.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Land Degradation
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Estimated nearly 3 million ha of cropland
ruined annually via erosion, 4 million ha
transformed into deserts, and 8 million ha
converted to non-agricultural uses.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Land Degradation
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Definitions of degradation are based on both
biological productivity and expectations of
what land should be like.
 Generally, land is considered degraded
when soil is impoverished or eroded, runoff is contaminated, or biodiversity is
diminished.
- Water and wind are the driving forces for
vast majority of soil degradation.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Land Degradation
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Erosion
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Erosion is an important natural process,
resulting in redistribution of the products of
geologic weathering, and is part of both soil
formation and soil loss.
 Worldwide, erosion reduces crop
production by equivalent of 1% of world
cropland per year.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Mechanisms of Erosion
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Rill Erosion - Small rivulets of running water
gather together and cut small channels in the
soil.
Gully Erosion - Rills enlarge to form bigger
channels too large to be removed by normal
tillage.
Streambank Erosion - Washing away of soil
from established streambanks.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Mechanisms of Erosion
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Wind can equal or exceed water as an
erosive force, especially in a dry climate and
on flat land.
 Intensive farming practices:
- Row crops leave soil exposed
- Weed free-fields
- Removal of windbreaks
- No crop-rotation or resting periods
- Continued monocultures
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
CHEMICAL
INPUTS
Fertilizers
Pesticides
Fungicides
Herbicides
(weed killers)
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Fertilizer
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Lack of nitrogen, potassium, and phosphorus
often limits plant growth.
 Adding nutrients via fertilizer usually
stimulates growth and increases crop yields.
- 1950 - 90 Average of 20 to 91 kg/ha
fertilizer used.
 Manure and nitrogen-fixing bacteria are
alternative methods of replenishing soil
nutrients.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Pesticide Problems
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Non-Target Species
 Up to 90% of pesticides never reach
intended target.
Pesticide Resistance
 Resistant members of a population survive
pesticide treatment and produce more
resistant offspring.
- Pest Resurgence
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Pesticide Resistance
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Environmental Persistence and Mobility
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Many persistent organic pollutants were
banned globally in 2001.
 Use was banned or restricted in
developing countries for years, but
between 1994 and 1996, the US shipped
more than 100,000 tons of DDT and POP’s
annually.
- Many returned to US in agricultural
products and migrating wildlife.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
DDT pesticide effect on birds;
U.S. recovery since ban
Still exported
to Periphery
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Human Health Problems
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WHO estimates between 3.5 and 5.0 million
people suffer acute pesticide poisoning, and
20,000 die, each year.
 At least two-thirds resulting from
occupational hazards in developing
countries.
 Long-term health effects difficult to
conclusively document.
- PCB’s have been linked to learning
deficiencies in children.
 Intake during mother’s pregnancy.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Alternatives to Pesticide Use
Crop Rotation
 Mechanical Cultivation
 Flooding Fields
 Habitat Diversification
 Growing in Pest-Free Zones
 Adjusting Planting Times
 Plant Mixed Polycultures
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Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
ENERGY
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Farming in industrialized countries is highly
energy-intensive.
 Between 1920-1980, energy use rose
directly with mechanization of agriculture,
and indirectly with spraying of chemicals.
 Altogether, US food system consumes
16% of total energy use.
- Most foods require more energy to
produce, process, and transport than we
yield from them.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Energy
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
NEW CROPS AND GENETIC ENGINEERING
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Most of world food comes from 16 widely
grown crops.
 At least 3,000 species of plants have been
used for food at some point in time.
- Many new or unconventional varieties
might be valuable food supplies.
 Winged-bean
 Triscale
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Green Revolution
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Most major improvements in farm production
have come from technological advances and
modification of a few well-known species.
 Corn yields jumped from 25 bushels per
acre to 130 per acre in last century.
- Most of gain accomplished through
conventional plant breeding.
 Also seen rise of dwarf varieties.
Green Revolution - Spread of new varieties
around the world.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Green Revolution
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
“Green Revolution”
benefits
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Core exports high-yield “miracle” seeds
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Needed oil-based fertilizers, pesticides
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Asian rice crop up 66% in 1965-85
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Favored areas with good soil, weather
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
“Green Revolution”
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
“Green Revolution”
drawbacks
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Favored farmers who could afford seeds,
inputs, machines, irrigation
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Indebted farmers lost land, moved to cities
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New “monocrops” lacked resistance to
disease/pests
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Environmental contamination, erosion
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Oriented to export “cash crops,” not domestic food
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Genetic Engineering
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Genetically Modified Organisms (GMO’s)
 Contain DNA possessing genes borrowed
from unrelated species.
- Can produce crops with pest-resistance
and wider tolerance levels.
- Opponents fear traits could spread to
wild varieties, and increased expense
would largely hurt smaller farmers.
 70% of all processed foods in NA contain
transgenic products.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Genetic Engineering
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Genetic Engineering
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Biotechnology:
Using organisms to…
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Make or modify products
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Improve plants or animals
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Develop new microorganisms
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Crossing different species
 Genetic engineering
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Genetically Modified Organisms (GMO)
Consumer concerns
began in Europe,
now in U.S. too
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Biotechnology
benefits in agriculture
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Increase yields
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Increase pest resistance
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Grow crops in new areas
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Biotechnology
drawbacks in agriculture
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High costs (available to few)
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Monocrops have less tolerance to disease
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Possible health effects, contamination of crops
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Corporate patents on life forms
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Bovine Growth
Hormone (BGH)
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Starlink corn
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Monarch butterflies
and corn pollen
Possible
effects of
Bt-modified
corn pollen
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cloning
First calf cloned in
Wisconsin, 1997.
Many clones die
of complications.
Ethical and
economic conflicts
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
SUSTAINABLE AGRICULTURE
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Soil Conservation
 Managing Topography
- Contour Plowing - Plowing across slope
to slow flow of water.
- Strip Farming - Planting different crops
in alternating strips along land contours.
- Terracing - Shaping land to create level
shelves of earth to hold water and soil.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Conservation
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Providing Ground Cover
 Annual row crops cause highest rates of
erosion because they leave soil bare for
much of the year.
- Leave crop residue after harvest.
- Plant cover crops after harvest.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Conservation
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Reduced Tillage
 Minimum Till - Chisel plow
 Conserv-Till - Coulter (Disc)
 No-Till - Drilling
Often farmers using conservation tillage must
depend relatively heavily on pesticides.
 Traditional tillage helped control weeds
and pests.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Summary
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Nutrition and Food Supplies
Major Food Sources
Soil
 Structure
 Erosion
Agricultural Resources
 Water
 Energy
Genetic Engineering
Sustainable Agriculture
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.