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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 - PowerPoint PPT Presentation
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Producing Food Has Major Environmental Impacts
Harmful effects of agriculture onBiodiversitySoilWaterAirHuman health
•Worse than any human activity
•¾ of water quality problems
Topsoil Erosion
Soil erosion Natural causes – flowing water, wind,
glaciersHuman causes – farming, mining,
deforestation, overgrazing, off-road vehicles
Two major harmful effects of soil erosion
Loss of soil fertilityWater pollution
Natural Capital Degradation: Global Soil Erosion
Drought and Human Activities Are Degrading Drylands
Desertification – mostly in Africa and AsiaModerate (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 desertification- expected to increase severe/ prolonged drought.
Results -drop infood production, water shortagesand refugees
Desertification of Arid and Semiarid Lands
Excessive Irrigation ProblemsMost 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, EgyptWaterlogging – accumulation of water
underground which raises the water tableFarmers 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 RevolutionsDepletion of water suppliesWasteful use of irrigation waterSoil salinizationClimate 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 FoodsProsCons
What about chimeraplasty?Inserting a Chemical InstructionThat attaches toA gene to get desired traits.No mixing genes Of different species
Food and Biofuel Production Systems Have Caused Major
Biodiversity LossesBiodiversity threatened when
Forest and grasslands are replaced with croplands
Agrobiodiversity threatened whenHuman-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
What environmental problems arise from food production?1.Topsoil erosion2.Drought and human activities degrade
drylands3.Excessive irrigation4.Limits to the Green Revolution5.Industrialized food production requires huge
inputs of energy6.Controversy over genetically engineered foods7.Food and biofuel production systems affect
biodiversity8.Industrialized meat production are energy
intensive9.Aquaculture can harm aquatic ecosystems
Nature Controls the Populations of Pests
What is a pest?
Natural enemies—predators, parasites, disease organisms—control pestsIn 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
PesticidesPesticides
InsecticidesHerbicidesFungicidesRodenticides (rats and mice)
Herbivores overcome plant defenses through natural selection: coevolution
First-generation pesticides – natural chemicals from plants
Second-generation pesticidesPaul Muller: DDTBenefits versus harm
Broad-spectrum agents- DDT, malathion and parathion
Persistence – length of time they remain deadly in the environment
DDTdichlorodiphenyltrichloroethane 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 CarsonBiologist
Silent Spring - 1962
Potential threats of uncontrolled use of pesticidesDDT pp. 87-91 and dieldrin 91-94
Advantages of Modern Synthetic Advantages of Modern Synthetic PesticidesPesticidesSave 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 DisadvantagesAccelerate 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 PesticidesNatural organic pesticides come from plants
tobacco produces toxic nicotine sulfate-toxic to insects and mammalspyrethrum- 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 injuredUnion 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
pests3 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 susceptibleFor 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 pesticidesU.S. federal agencies regulate sale/use
EPAUSDAFDAFederal Insecticide, Fungicide, and Rodenticide Act
(FIFRA) first passed in 1947 and amended in 1972Food 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 UseFood, 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 PesticidesFool 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 perfumesE.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
DisadvantagesTakes knowledge of the specific pestTakes timeMethods may vary from place to placeInitial costs highGovernment 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
12.4 HOW DO WE PROTECT CROPS FROM PESTS?
1.Nature controls most pest populations
2.Use pesticides3.Laws and treaties4.Biological, ecological and other
alternatives to pesticides5.Integrated pest management
Food Production and SecurityControl prices – government can set limits on food
pricesProvide subsidies – government can provide subsidiesLet the marketplace decide
United Nations Children’s Fund (UNICEF) suggests these measures to save children from effects of povertyImmunizing children against childhood diseasesEncourage breast-feeding Prevent dehydration in infants and children – mix
sugar/salt in their waterPrevent blindness by giving children a vitamin A capsule
2x/yrProvide family planning servicesIncrease education for womenPREVENTING HEALTH PROBLEMS IN CHILDREN CAN
INCREASE FOOD SECURITY
Eliminate or minimize plowing/tillingConservation 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 wind1930-1937 severe droughtfarmers 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 place-
Winds 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=x2CiDaUYr90
Restore Soil FertilityOrganic 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 salinizationPrevention – reduce irrigation/plant salt tolerant
cropsClean-up – stop growing/ flush soil/underground
drainage systems
Desertification, reducePopulation growthOvergrazingDeforestationDestructive forms of planting, irrigation, and mining
Practice More Sustainable AquacultureOpen-ocean aquaculture
Farm inland in zero discharge ponds/tanksSalmon, 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 proteinpoultry 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
MOVE DOWN THE FOOD CHAIN AND SLOW POPULATION GROWTHMEAT 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.
Fig. 12-31, p. 307
SOLUTIONS
Sustainable Organic Agriculture
More LessHigh-yield polyculture
Soil erosion
Organic fertilizers
Aquifer depletion
Biological pest control
Overgrazing
OverfishingIntegrated pest management
Loss of biodiversity
Efficient irrigation
Perennial crops Subsidies for unsustainable farming and fishing
Food waste
Crop rotationWater-efficient crops
Soil salinizationSoil conservationSubsidies for sustainable farming and fishing
Population growth
Poverty
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 CoffeeCoffee Grown in the sunlight
Coffee Grown under the shade of trees
Planted in higher densityNeeds more fertilizers and pesticidesSo much coffee was produced that the demand decreased and prices decreasedIncreased erosion and toxic runoffSoil lacks nutrients
Lower yield No need for fertilizers and pesticides because the birds and insects take care of disease and hungry insectsGreater biodiversitySoil is healthy and can produce coffee yearly
Modern industrial agriculture violates the 4 basic principles of sustainability
Too many fossil fuelsToo little recyclingAccelerates soil erosionDoes little to preserve
agrobiodiversity and can destroy/degrade wildlife habitats
HOW CAN WE PRODUCE FOOD MORE SUSTAINABLY?1.Reduce soil erosion2.Restore soil fertility3.Reduce soil salinization and desertification4.Practice more sustainable aquaculture5.Produce mean more efficiently and humanely6.Move down the food chain and slow population
growth7.Shift to more sustainable agriculture8.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.