12.3
What environmental
problems arise from food
production?
Producing Food Has Major
Environmental Impacts
Harmful effects of agriculture on
Biodiversity
Soil
Water
Air
Human health
Worse than any human activity
¾ of water quality problems
•
•
Topsoil Erosion
Soil erosion
Natural causes – flowing water, wind,
glaciers
Human causes – farming, mining,
deforestation, overgrazing, off-road
vehicles
Two major harmful effects of soil erosion
Loss of soil fertility
Water pollution
Natural Capital Degradation:
Global Soil Erosion
Drought and Human Activities Are Degrading
Drylands
Desertification – mostly in Africa and Asia
Moderate (10-25% drop in productivity)
Severe (25-50% drop in productivity)
Very severe (more than 50% drop)
http://www.youtube.com/watch?feature=endscreen&NR=1&v=FKEKhdt7Mks
Effect of global warming on desertificationexpected to increase severe/ prolonged
drought.
Desertification of Arid and Semiarid Lands
Results -drop in
food production,
water shortages
and refugees
Excessive Irrigation Problems
Most irrigation water has many dissolved salts from
rocks and soil
Salinization – evaporation of water, leaving the
salt behind. Stunts crop growth, lowers yields
and kill plants/ruin land
Worst in China, India, Egypt
Waterlogging – accumulation of water
underground which raises the water table
Farmers often water often in order to leach the
salts deeper into the soil, but if water table rises,
the saline water can be reached by the plants’
roots
Limits to Expanding the Green Revolutions
Depletion of water supplies
Wasteful use of irrigation water
Soil salinization
Climate change (melting mountain
glaciers that provide summer waters)
Farmers lack the money to irrigate
improve efficiency of irrigation
techniques
GM crops that are more drought and
cold tolerant and multicropping can
increase yields
•
•
Industrialized Food Production Requires Huge
Inputs of Energy
Industrialized food production and
consumption have a large net energy
loss
Food travels a total of 1300 miles from farm to
plate!
Industrialized Agriculture uses ~17%
of All Commercial Energy Used in the U.S.
Controversy over Genetically Engineered Foods
Pros
Cons
What about
chimeraplasty?
Inserting a
Chemical
Instruction
That attaches to
A gene to get
desired traits.
No mixing genes
Of different
species
Food and Biofuel Production Systems
Have Caused Major Biodiversity Losses
Biodiversity threatened when
Forest and grasslands are replaced with
croplands
Agrobiodiversity threatened when
Human-engineered monocultures are used
Importance of seed banks (97% of food plant
varieties available in the 1940s no longer
exist)
Newest: underground vault in the
Norwegian Arctic
Industrialized Meat Production Has
Harmful Environmental Consequences
Producing Fish through Aquaculture
Can Harm Aquatic Ecosystems
What environmental problems arise
from food production?
1.Topsoil erosion
2.Drought and human activities degrade drylands
3.Excessive irrigation
4.Limits to the Green Revolution
5.Industrialized food production requires huge inputs
of energy
6.Controversy over genetically engineered foods
7.Food and biofuel production systems affect
biodiversity
8.Industrialized meat production are energy intensive
9.Aquaculture can harm aquatic ecosystems
12.4
How can we protect crops
from pests more
sustainably?
Nature Controls the Populations of Pests
What is a pest?
Natural enemies—predators, parasites, disease
organisms—control pests
In natural ecosystems
In many polyculture agroecosystems
there is a balance- spiders kill more insects every
year than chemicals do!
What will happen if we kill the pests?
Spiders are Important Insect Predators
Pesticides
Pesticides
Insecticides
Herbicides
Fungicides
Rodenticides (rats and mice)
Herbivores overcome plant defenses through natural selection:
coevolution
First-generation pesticides – natural chemicals from plants
Second-generation pesticides
Paul Muller: DDT
Benefits versus harm
Broad-spectrum agents- DDT, malathion and parathion
Persistence – length of time they remain deadly in the
environment
DDT
dichlorodiphenyltrichloroethane
a chlorinated hydrocarbon
Used during WW II to kill mosquitoes
in order to prevent malaria and typhus.
It is not water soluble so it accumulates in the tissues of
organisms.
Got in the waters, then fish, then birds.
Caused bird eggs to be too thin so they broke when sat on
Contributed to the declining numbers of bald eagles, bats,
peregrine falcons
Banned in 1972, but many countries still use it.
Why Are We Concerned About DDT?
Even though DDT has been banned since 1972, it can
take more than 15 years to break down in the
environment.
What harmful effects can DDT have on us?
Damages the liver
Temporarily damages the nervous system
Can cause liver cancer
Damages reproductive system
How are we exposed to DDT?
By eating contaminated fish and shellfish
Infants may be exposed through breast milk
By eating imported food directly exposed to DDT
By eating crops grown in contaminated soil
Rachel Carson
Biologist
Silent Spring - 1962
Potential threats of uncontrolled use of pesticides
DDT pp. 87-91 and dieldrin 91-94
Advantages of Modern Synthetic Pesticides
Save human lives
Increases food supplies and profits for farmers
Work quickly
Health risks are very low relative to their benefits
New pest control methods: safer and more effective
Synthetic Pesticides Have Disadvantages
Accelerate the development of genetic resistance to
pesticides by pest organisms
Expensive for farmers
Some insecticides kill natural predators and parasites
that help control the pest population
Pollution in the environment
Some harm wildlife
Some are human health hazards
Chemical groups of Pesticides
Natural organic pesticides come from plants
tobacco produces toxic nicotine sulfate-toxic to insects
and mammals
pyrethrum- comes from chrysanthemum and is used in
animal dips and flea shampoo
Chlorinated hydrocarbons- DDT, aldrin, dieldrin,
chlordane- are nerve toxins that cause nausea,
vomiting, convulsions and death. Linked to fertility
disorders and may be carcinogens. Highly persistent,
fat soluble and subject to biomagnification
Organophosphates – malathion, parathion and
tetrethylpyrophosphate. Used as nerve agents in
WWII. Break down quickly. More toxic in lower
amounts that chlorinated hydrocarbons because they
are absorbed quickly. Cause headache, slow heart
beat, confusion, paralysis, coma, death.
Carbamates – are insecticides, herbicides and fungicides.
Lack persistence and bioaccumulation. Examples are
carbaryl (Sevin) and aldicarb (Temik). Also act on the
nervous system and have same effects.
Case Study- Bhopal, India 1984
Poisonous gas leak that killed 10,000 – 30,000 and more
than 500,000 were injured
Union carbide was producing an insecticide- called Sevin
The chemical name was methyl icocyanate (MIC)
Once inhaled, MIC destroys the respiratory system with
lightning speed, causes irreversible blindness and
burns the pigment of the skin
However…
Pesticide use has not reduced U.S. crop loss to pests
3 conclusions are:
1. Loss of crops today is greater than in the 1940s. 37% of
crops lost now compared to 31%
2. High environmental, health, and social costs with use
3. Use alternative pest management practices
Pesticide industry refutes these findings
Children are most susceptible
For their body size, they eat more food,
drink more water and breathe more air
THE UNPREDICTABILITY OF INSECTICIDES
THE CATS OF BORNEO
Malaria and dieldrin (relative to DDT)
Kill the mosquitos to prevent malaria!
Laws and Treaties Can Help to Protect Us from the
Harmful Effects of Pesticides
Over 25,000 different commercial pesticides
U.S. federal agencies regulate sale/use
EPA
USDA
FDA
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
first passed in 1947 and amended in 1972
Food Quality Protection Act 1996- EPA must reduce allowed
levels of pesticide residues in food
Effects of active and inactive pesticide ingredients are
poorly documented
Circle of poison, boomerang effect – residues of banned
pesticides exported to countries can return to those countries
on imported food. Wind also carries pesticides
Laws Controlling Pesticide Use
Food, Drug, and Cosmetics Act (1938)
Pesticide Chemicals Amendment (1954)
Delaney Clause (1958) (a zero cancer
risk standard)
Federal Insecticide, Fungicide, and
Rodenticide Act (1947) federal control
of pesticide distribution, sale, and use
Food Quality Protection Act (1996)
Alternatives to Using Pesticides
Fool the pest – rotating crops, adjust planting times
Provide homes for pest enemies
Implant genetic resistance- GE used to speed up development
of pest/disease-resistant crop strains
Bring in natural enemies
Use insect perfumes
E.g., pheromones (sex attractants)
Bring in hormones – use to disrupt developmental processes
Scald them with hot water – works on cotton, alfalfa
Integrated Pest Management
Integrated pest management (IPM)
Coordinate: cultivation, biological controls,
and chemical tools to reduce crop damage
to an economically tolerable level
Disadvantages
Takes knowledge of the specific pest
Takes time
Methods may vary from place to place
Initial costs high
Government subsidies for using chemicals
Systems Approach- Integrated Pest
Management (IPM)
IPM
Combination of pest
control methods that
keeps pest population
low without economic
loss
Conventional pesticides
are used sparingly when
other methods fail
IPM Project
12.4 HOW DO WE PROTECT CROPS FROM PESTS?
1.Nature controls most pest
populations
2.Use pesticides
3.Laws and treaties
4.Biological, ecological and other
alternatives to pesticides
5.Integrated pest management
12.5
How can we improve food
security?
Food Production and Security
Control prices – government can set limits on food prices
Provide subsidies – government can provide subsidies
Let the marketplace decide
United Nations Children’s Fund (UNICEF) suggests these
measures to save children from effects of poverty
Immunizing children against childhood diseases
Encourage breast-feeding
Prevent dehydration in infants and children – mix
sugar/salt in their water
Prevent blindness by giving children a vitamin A capsule
2x/yr
Provide family planning services
Increase education for women
PREVENTING HEALTH PROBLEMS IN CHILDREN CAN
INCREASE FOOD SECURITY
12.6
HOW CAN WE PRODUCE
FOOD MORE
SUSTAINABLY?
Soil Conservation Methods- Reduce soil
erosion
Eliminate or minimize plowing/tilling
Conservation tillage farming- uses no machinery-
leaves the crop residue on the surface to decompose –
a special machine drills seeds directly through the crop
residues
This methods helps store carbon and keep other
nutrients in the soil –uses less fertilizers/ lowers use
of water/fertilizer runoff and tractor fuel
But cannot be used for all crops, costly machinery, and
increase use of herbicides
Case in Point:
American Dust Bowl
Great Plains have low precipitation
and subject to drought and wind
1930-1937 severe drought
farmers had plowed land deeply and
did not rotate crops, leave them
fallow or plant cover crops to
prevent erosion- No natural
vegetation roots to hold soil in
placeWinds blew soil as far east as NYC and
DC.
Farmers went bankrupt- many moved
to Ca and became migrant workers.
http://www.youtube.com/watch?v=x2CiDaUY
r90
Restore Soil Fertility
Organic fertilizer - animal manure, green manure
(freshly cut or growing green vegetation), compost
(microorganisms break down organic matter like
leaves, crop residues)
Crop rotation to preserve nutrients – corn and cotton
deplete nitrogen and legumes add nitrogen
Manufactured inorganic fertilizers- contain compounds
that add nitrogen, phosphorus and potassium – do not
add organic material to the soil – need to be controlled
carefully since fertilizers can run off the land and
pollute the waters
Reduce Soil Salinization and Desertification
Soil salinization
Prevention – reduce irrigation/plant salt tolerant crops
Clean-up – stop growing/ flush soil/underground drainage
systems
Desertification, reduce
Population growth
Overgrazing
Deforestation
Destructive forms of planting, irrigation, and mining
Practice More Sustainable Aquaculture
Open-ocean aquaculture
Farm inland in zero discharge ponds/tanks
Salmon, tuna and cod are carnivores.
Carp, tilapia and catfish are herbivores – more sustainable
Polyculture – raising fish/shrimp/algae/seaweed/shellfish
together and the wastes of one is food for another.
Shrimp and tilapia can be grown together for they feed
at different levels.
Produce Meat More Efficiently and Humanely
Shift to more grain-efficient forms of protein
poultry and plant eating farmed fish
Develop meat substitutes; eat less meat
Whole Food Markets: more humane treatment of animals
38% of world’s grain harvest and 37% of world’s fish
catch are used to produce animal protein
Whole foods 5-step animal rating
MOVE DOWN THE FOOD CHAIN AND
SLOW POPULATION GROWTH
MEAT PRODUCTION/DELIVERY CAUSES 40% MORE GHG
THAN ALL THE WORLD’S MODES OF
TRANSPORTATION.
DECREASING THE AMOUNT OF MEAT AND SWITCHING
TO MORE ENERGY EFFICIENT CHICKEN AND
HERBIVOROUS FISH IS ALSO MORE HEALTHY AND
INCREASES LIFE EXPECTANCY.
MEDITERRANEAN-TYPE DIETS INCLUDE LESS
MEAT/CHEESE/SEAFOOD
VEGETARIAN DIETS
SLOWING THE POPULATION GROWTH REDUCES
HARMFUL EFFECTS OF AGRICULTURE.
What is Organic Farming?
Farming with little or no synthetic fertilizers/pesticides/
or GE seeds
SOLUTIONS
Sustainable Organic Agriculture
More
High-yield
polyculture
Organic
fertilizers
Biological pest
control
Integrated pest
management
Efficient
irrigation
Perennial crops
Crop rotation
Water-efficient
crops
Soil
conservation
Subsidies for
sustainable
farming and
fishing
Less
Soil erosion
Aquifer
depletion
Overgrazing
Overfishing
Loss of
biodiversity
Food waste
Subsidies for
unsustainable
farming and
fishing
Soil salinization
Population
growth
Poverty
Fig. 12-31, p. 307
Buy Locally Grown Food- be a locovore!
Supports local economies
Reduces environmental impact on food production
Community-supported agriculture (CSA)
Farmers’ markets
Sun Coffee vs Shade Coffee
Coffee Grown in the
sunlight
Planted in higher
density
Needs more fertilizers
and pesticides
So much coffee was
produced that the
demand decreased and
prices decreased
Increased erosion and
toxic runoff
Soil lacks nutrients
Coffee Grown under the
shade of trees
Lower yield
No need for fertilizers
and pesticides because
the birds and insects
take care of disease
and hungry insects
Greater
biodiversity
Soil is healthy
and can
produce
coffee yearly
Modern industrial agriculture violates
the 4 basic principles of sustainability
Too many fossil fuels
Too little recycling
Accelerates soil erosion
Does little to preserve agrobiodiversity
and can destroy/degrade wildlife
habitats
HOW CAN WE PRODUCE FOOD
MORE SUSTAINABLY?
1.Reduce soil erosion
2.Restore soil fertility
3.Reduce soil salinization and desertification
4.Practice more sustainable aquaculture
5.Produce mean more efficiently and humanely
6.Move down the food chain and slow population
growth
7.Shift to more sustainable agriculture
8.Buy locally grown food
Albert Einstein
“Nothing will benefit human health and increase chances
of survival of life on earth as much as the evolution of
a vegetarian diet.”
What do you think about this quote, and would you be
willing to eat less meat?
Other vegetarians…
Leonardo Da Vinci, Gandhi, Pythagoras, Mark Twain
Is modern agriculture really the best
way to feed a population?
Read the article
and answer the
questions.
Elements