4 Natural Capital Degradation: Global Soil Erosion Topsoil ErosionSoil erosionNatural causes – flowing water, wind, glaciersHuman causes – farming, mining, deforestation, overgrazing, off-road vehiclesTwo major harmful effects of soil erosionLoss of soil fertilityWater pollutionNatural Capital Degradation: Global Soil Erosion
5 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)Effect of global warming on desertification- expected to increase severe/ prolonged drought.Results -drop infood production,water shortagesand refugeesDesertification of Arid and Semiarid Lands
6 Excessive Irrigation Problems Most irrigation water has many dissolved salts from rocks and soilSalinization – evaporation of water, leaving the salt behind. Stunts crop growth, lowers yields and kill plants/ruin landWorst 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
7 Limits to Expanding the Green Revolutions Depletion of water suppliesWasteful use of irrigation waterSoil salinizationClimate change (melting mountain glaciers that provide summer waters)Farmers lack the money to irrigateimprove efficiency of irrigation techniquesGM crops that are more drought and cold tolerant and multicropping can increase yields
8 Industrialized Food Production Requires Huge Inputs of Energy Industrialized food production and consumption have a large net energy lossFood travels a total of 1300 miles from farm to plate!Industrialized Agriculture uses ~17%of All Commercial Energy Used in the U.S.
9 Controversy over Genetically Engineered Foods ProsConsWhat aboutchimeraplasty?Inserting aChemicalInstructionThat attaches toA gene to getdesired traits.No mixing genesOf differentspecies
10 Food and Biofuel Production Systems Have Caused Major Biodiversity Losses Biodiversity threatened whenForest and grasslands are replaced with croplandsAgrobiodiversity threatened whenHuman-engineered monocultures are usedImportance of seed banks (97% of food plant varieties available in the 1940s no longer exist)Newest: underground vault in the Norwegian Arctic
11 Industrialized Meat Production Has Harmful Environmental Consequences
12 Producing Fish through Aquaculture Can Harm Aquatic Ecosystems
13 What environmental problems arise from food production? Topsoil erosionDrought and human activities degrade drylandsExcessive irrigationLimits to the Green RevolutionIndustrialized food production requires huge inputs of energyControversy over genetically engineered foodsFood and biofuel production systems affect biodiversityIndustrialized meat production are energy intensiveAquaculture can harm aquatic ecosystems
14 How can we protect crops from pests more sustainably? 12.4How can we protect crops from pests more sustainably?
15 Nature Controls the Populations of Pests What is a pest?Natural enemies—predators, parasites, disease organisms—control pestsIn natural ecosystemsIn many polyculture agroecosystemsthere 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
16 Pesticides Pesticides InsecticidesHerbicidesFungicidesRodenticides (rats and mice)Herbivores overcome plant defenses through natural selection: coevolutionFirst-generation pesticides – natural chemicals from plantsSecond-generation pesticidesPaul Muller: DDTBenefits versus harmBroad-spectrum agents- DDT, malathion and parathionPersistence – length of time they remain deadly in the environment
17 DDT dichlorodiphenyltrichloroethane a chlorinated hydrocarbon Used during WW II to kill mosquitoesin 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 onContributed to the declining numbers of bald eagles, bats, peregrine falconsBanned in 1972, but many countries still use it.
18 Why Are We Concerned About DDT 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
19 Rachel Carson Biologist Silent Spring - 1962 Potential threats of uncontrolled use of pesticidesDDT pp and dieldrin 91-94
20 Advantages of Modern Synthetic Pesticides Save human livesIncreases food supplies and profits for farmersWork quicklyHealth risks are very low relative to their benefitsNew pest control methods: safer and more effective
21 Synthetic Pesticides Have Disadvantages Accelerate the development of genetic resistance to pesticides by pest organismsExpensive for farmersSome insecticides kill natural predators and parasites that help control the pest populationPollution in the environmentSome harm wildlifeSome are human health hazards
23 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.
24 Carbamates – are insecticides, herbicides and fungicides 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
25 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 use3. Use alternative pest management practicesPesticide industry refutes these findingsChildren are most susceptibleFor their body size, they eat more food,drink more water and breathe more air
27 THE UNPREDICTABILITY OF INSECTICIDES THE CATS OF BORNEO Malaria and dieldrin (relative to DDT) Kill the mosquitos to prevent malaria!
28 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/useEPAUSDAFDAFederal Insecticide, Fungicide, and Rodenticide Act (FIFRA) first passed in 1947 and amended in 1972Food Quality Protection Act EPA must reduce allowed levels of pesticide residues in foodEffects of active and inactive pesticide ingredients are poorly documentedCircle of poison, boomerang effect – residues of banned pesticides exported to countries can return to those countries on imported food. Wind also carries pesticides
29 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 useFood Quality Protection Act (1996)
30 Alternatives to Using Pesticides Fool the pest – rotating crops, adjust planting timesProvide homes for pest enemiesImplant genetic resistance- GE used to speed up development of pest/disease-resistant crop strainsBring in natural enemiesUse insect perfumesE.g., pheromones (sex attractants)Bring in hormones – use to disrupt developmental processesScald them with hot water – works on cotton, alfalfa
31 Integrated Pest Management Integrated pest management (IPM)Coordinate: cultivation, biological controls, and chemical tools to reduce crop damage to an economically tolerable levelDisadvantagesTakes knowledge of the specific pestTakes timeMethods may vary from place to placeInitial costs highGovernment subsidies for using chemicals
32 Systems Approach- Integrated Pest Management (IPM) Combination of pest control methods that keeps pest population low without economic lossConventional pesticides are used sparingly when other methods fail
34 12.4 HOW DO WE PROTECT CROPS FROM PESTS? Nature controls most pest populationsUse pesticidesLaws and treatiesBiological, ecological and other alternatives to pesticidesIntegrated pest management
35 How can we improve food security? 12.5How can we improve food security?
36 Food Production and Security Control prices – government can set limits on food pricesProvide subsidies – government can provide subsidiesLet the marketplace decideUnited Nations Children’s Fund (UNICEF) suggests these measures to save children from effects of povertyImmunizing children against childhood diseasesEncourage breast-feedingPrevent 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
37 HOW CAN WE PRODUCE FOOD MORE SUSTAINABLY? 12.6HOW CAN WE PRODUCE FOOD MORE SUSTAINABLY?
39 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 residuesThis methods helps store carbon and keep other nutrients in the soil –uses less fertilizers/ lowers use of water/fertilizer runoff and tractor fuelBut cannot be used for all crops, costly machinery, and increase use of herbicides
40 Case in Point: American Dust Bowl Great Plains have low precipitation and subject to drought and windsevere 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.
41 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
42 Reduce Soil Salinization and Desertification Prevention – reduce irrigation/plant salt tolerant cropsClean-up – stop growing/ flush soil/underground drainage systemsDesertification, reducePopulation growthOvergrazingDeforestationDestructive forms of planting, irrigation, and mining
44 Practice More Sustainable Aquaculture Open-ocean aquacultureFarm inland in zero discharge ponds/tanksSalmon, tuna and cod are carnivores.Carp, tilapia and catfish are herbivores – more sustainablePolyculture – 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.
45 Produce Meat More Efficiently and Humanely Shift to more grain-efficient forms of proteinpoultry and plant eating farmed fishDevelop meat substitutes; eat less meatWhole Food Markets: more humane treatment of animals38% of world’s grain harvest and 37% of world’s fish catch are used to produce animal protein
47 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.
48 What is Organic Farming? Farming with little or no synthetic fertilizers/pesticides/ or GE seeds
49 SOLUTIONS Sustainable Organic Agriculture More Less High-yield polycultureSoil erosionAquifer depletionOrganic fertilizersOvergrazingBiological pest controlOverfishingIntegrated pest managementLoss of biodiversityEfficient irrigationFood wasteSubsidies for unsustainable farming and fishingPerennial cropsFigure 12.31Major components of more sustainable, low-throughput agriculture based mostly on mimicking and working with nature (Concept 12-6B). Question: Which two solutions do you think are the most important? Why?Crop rotationWater-efficient cropsSoil salinizationSoil conservationPopulation growthSubsidies for sustainable farming and fishingPovertyFig , p. 307
50 Buy Locally Grown Food- be a locovore! Supports local economiesReduces environmental impact on food productionCommunity-supported agriculture (CSA)Farmers’ markets
51 Sun Coffee vs Shade Coffee Coffee Grown in the sunlightCoffee Grown under the shade of treesPlanted 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 nutrientsLower 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
52 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
53 HOW CAN WE PRODUCE FOOD MORE SUSTAINABLY? Reduce soil erosionRestore soil fertilityReduce soil salinization and desertificationPractice more sustainable aquacultureProduce mean more efficiently and humanelyMove down the food chain and slow population growthShift to more sustainable agricultureBuy locally grown food
54 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
55 Is modern agriculture really the best way to feed a population Is modern agriculture really the best way to feed a population? Read the article and answer the questions.