1/4 What is the single most impactful activity humans have on the environment?

Transcription

1 1/4 What is the single most impactful activity humans have on the environment?

2 1/8! You, as a food buyer, you have the distinct privilege of proactively participating in shaping the world your children will inherit.! Joel Salatin 2

3 Chapter 11 Feeding the World

4 Global Undernutrition

5 Nutritional Requirements! Undernutrition- not consuming enough calories to be healthy.! Malnourished- a persons diet lacks the correct balance of proteins, carbohydrates, vitamins, and minerals even though they get enough calories.! Overnutrition- too many calories and improper foods that causes a person to become overweight.

6 Annual Meat Consumption

7 Global Grain Production,

8 Reasons for Undernutrition and Malnutrition! Poverty! Political and economic factors! Agricultural resources being diverted to feed livestock and poultry rather than people

9 The Green Revolution! New management techniques and mechanization as well as the triad of fertilization, irrigation, and improved crop varieties. This has increased food production dramatically.

10 Irrigation Problems! Waterlogging- when the soil remains under water for prolonged periods which impairs root growth because the roots cannot get oxygen.! Salinization- when the small amounts of salts in irrigation water become highly concentrated on the soil surface through evaporation.

11 1/11 You are what you eat, eats. Micheal Pollan 11

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15 Drip irrigation (efficiency 90 95%) Gravity flow (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river. Above- or belowground pipes or tubes deliver water to individual plant roots. Center pivot (efficiency 80% 95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Fig , p. 325

16 Fertilizers! Organic fertilizers- organic matter from plants and animals. Typically made from animal manure that has been allowed to decompose.! Inorganic fertilizers (synthetic)- fertilizers that are produced commercially. This is usually done by combusting natural gas, which allows nitrogen from the atmosphere to be fixed and captured in fertilizer.

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19 Pesticides! Pesticide- a substance that kills or controls organisms that people consider pests.! Insecticide- target insects! Herbicides- target plants

20 Pesticides! Broad-spectrum pesticides- designed to kill many different types of pests.! Selective pesticides- designed to kill a narrower range of organisms.

21 Pesticides! Persistent- pesticides that remain in the environment a long time.! Nonpersistent- pesticide that breaks down relatively rapidly, usually in weeks to months.

22 Pesticides! Bioaccumulation- some pesticides are found to build up over time in the fatty tissues of predators.! An example was DDT.! When an organism containing the pesticide is eaten, the chemical is transferred to the consumer.! This eventually leads to very high pesticide concentrations at high trophic levels.

23 Pesticides! Resistance- pest populations may evolve resistance to a pesticide over time. These are said to be resistant.! Pesticide treadmill- the cycle of pesticide development followed by pest resistance, followed by development of a new pesticide.

24 PROTECTING FOOD RESOURCES: PEST MANAGEMENT " Advantages and disadvantages of conventional chemical pesticides. Figure 13-28

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26 PROTECTING FOOD RESOURCES: PEST MANAGEMENT " LD 50 Lethal Dosage required to kill 50 percent of a population of test animals. " Stated in milligrams (mg) of pesticide per kilogram (kg) of body weight. " A pesticide with an LD 50 value of 10 mg/kg is 10 times more toxic than a pesticide with an LD 50 of 100 mg/kg.

27 Percentage of population killed by a given dose LD 50 Curve When speaking about chemical pesticides, you can compare them in terms of their LD-50, or the amount of the chemical it takes to kill ½ of the population. LD Dose (hypothetical units) In this example, the LD-50 would be 7 hypothetical units

28 Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans Toxicity Rating LD50 (milligrams per kg of body weight)* Average Lethal Dose Examples Supertoxic Extremely toxic Very toxic Toxic Moderately toxic Slightly toxic Essentially nontoxic Less than 0.01 Less than ,000 5,000 15,000 15,000 or greater Some well-known chemical pesticides, long banned in the USA Less than 1 drop Less than 7 drops 7 drops to 1 teaspoon 1 teaspoon to 1 ounce 1 ounce to 1 pint 1 pint to 1 quart More than 1 quart Nerve gases, botulism toxin, mushroom toxins, dioxin (TCDD) Potassium cyanide, heroin, atropine, parathion, nicotine Mercury salts, morphine, codeine Lead salts, DDT, sodium hydroxide, sodium fluoride, sulfuric acid, caffeine, carbon tetrachloride Methyl (wood) alcohol, ether, phenobarbital, amphetamines (speed), kerosene, aspirin Ethyl alcohol, Lysol, soaps Water, glycerin, table sugar *Dosage that kills 50% of individuals exposed Amounts of substances in liquid form at room temperature that are lethal when given to a 70.4-kg (155-pound) human Important Note: The lower the LD-50 a chemical has, the stronger it is. Think: the less amount it takes to kill ½ the test population, the stronger it must be.

29 1/18 Harmony with the land is like harmony with a friend; you cannot cherish his right hand and chop off his left Aldo Leopold

30 Farming Methods! Conventional agriculture- industrial agriculture where labor is reduced and machinery is used.! Traditional farming- still used in the developing world where human labor is used and not machinery.! Shifting agriculture- used in areas with nutrient poor soils. It involves planting an area for a few years until the land is depleted of nutrients and then moving to another area and repeating the process.! Nomadic grazing- moving herds of animals to find productive feeding grounds.

31 Types of Agriculture Industrialized Agriculture Agribusiness Developed countries Land moderate amount Labor low Capital Costs high (use a lot of fertilizer, pesticides, and irrigation systems) Energy Use (fossil fuels) high Environmental Impacts - high

32 Industrialized Agriculture

33 Types of Agriculture Intensive Traditional (Rice fields, China, Thailand) Developing countries Capital Costs low (use fertilizer and will divert water for irrigation through dams on occasion) Energy use (fossil fuels) low Environmental Impacts (low-moderate)

34 Intensive Agriculture Rice Paddies

35 Types of Agriculture Shifting Cultivation Developing countries Land large tracts of tropical forests cleared and used for agriculture Labor low-moderate Capital Costs low (rarely use fertilizer) Energy use low to none Shift agricultural plots of land until nutrients are restored to land. Environmental Impacts (moderate)

36 Types of Agriculture Shifting Cultivation Developing countries Land large tracts of tropical forests cleared and used for agriculture Labor low-moderate Capital Costs low (rarely use fertilizer) Energy use low to none Shift agricultural plots of land until nutrients are restored to land. Environmental Impacts (moderate)

37 Industrialized agriculture Shifting cultivation Plantation agriculture Nomadic herding Intensive traditional agriculture No agriculture

38 Monocropping! Growing a large amount of a single species of plant.

39 Agricultural Methods 1. Polyvarietal Cultures a plot is planted with several species of the same crop. Example. Rice Type A = normal strain Type B = drought-resistant strain Type C = nutrient-deficient strain Multi-strains ensure that a crop will bring a profit under varying conditions, since annual weather is unpredictable.

40 Polyvarietal Strains

41 Agricultural methods 2. Intercropping two or more different crops are grown at the same time on a single plot. Example, carbohydrate rich grains such as corn next to protein-rich legumes such as alfalfa that fixes nitrogen in the soils due to Rhizobium sp.

42 Intercropping

43 Agricultural Methods 3. Agroforestry crops and trees planted together. This may include plantation trees. Trees provide shading to promote moisture-retention in soils. Example, fruit-bearing trees planted with a grain and/or legume.

44 Agroforestry

45 Agricultural Methods Polyculture a complex form of intercropping. Many different species/varieties of plants will mature at different times. This ensures yearround crop production and habitat for pests and wildlife. Produces high sustainable yields. Provides medicine, fuel, natural pesticides and natural fertilizers. Reduces environmental degradation from pesticides and irrigation and reduces crop losses overall.

46 Figure THE GENE REVOLUTION " The winged bean, a GMF, could be grown to help reduce malnutrition and the use of large amounts of inorganic fertilizers.

47 Benefits of Genetic Engineering! Greater yield! Greater food quality! Reductions in pesticide use! Reduction of world hunger by increased food production! Increased profits

48 Concerns about Genetically Modified Organisms! Safety for human consumption! Effects on biodiversity! Regulation of genetically modified organisms

49 Desertification! Desertification- When soil is degraded by agriculture to the point at which they are not longer productive.

50 Biodiversity Loss Soil Water Air Pollution Human Health Loss and Erosion Water waste Greenhouse gas Nitrates in degradation of emissions from drinking water grasslands, Loss of fertility Aquifer depletion fossil fuel use forests, and Salinization wetlands Fish kills from pesticide runoff Killing wild predators to protect livestock Loss of genetic diversity of wild crop strains replaced by monoculture strains Waterlogging Desertification Increased runoff and flooding from cleared land Sediment pollution from erosion Fish kills from pesticide runoff Surface and groundwater pollution from pesticides and fertilizers Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes Other air pollutants from fossil fuel use Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers Belching of the greenhouse gas methane by cattle Pollution from pesticide sprays Pesticide residues in drinking water, food, and air Contamination of drinking and swimming water with disease organisms from livestock wastes Bacterial contamination of meat Fig , p. 285

51 High-Density Animal Farming! CAFOs (concentrated animal feeding operations)- large structures where animals are being raised in high density numbers.

52 Trade-Offs Animal Feedlots Advantages Disadvantages Increased meat production Higher profits Less land use Reduced overgrazing Reduced soil erosion Help protect biodiversity Need large inputs of grain, fish meal, water, and fossil fuels Concentrate animal wastes that can pollute water Antibiotics can increase genetic resistance to microbes in humans Fig , p. 289

53 Harvesting of Fish and Shellfish! Fishery- a commercially harvestable population of fish within a particular ecological region.! Fishery collapse- the decline of a fish population by 90% or more.! Bycatch- unintentional catch of non-target species.

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55 Aquaculture! Aquaculture- the farming of aquatic organisms such as fish, shellfish, and seaweeds.

56 Trade-Offs Advantages Aquaculture Disadvantages High efficiency High yield in small volume of water Can reduce overharvesting of conventional fisheries Low fuel use High profits Profits not tied to price of oil Needs large inputs of land, feed, and water Large waste output Destroys mangrove forests and estuaries Uses grain to feed some species Dense populations vulnerable to disease Tanks too contaminated to use after about 5 years Fig , p. 292

57 Sustainable Agriculture! Sustainable agriculture- producing enough food to feed the world s population without destroying the land, polluting the environment, or reducing biodiversity.! Intercropping- two or more crop species are planted in the same field at the same time.! Crop rotation- rotating crops species from season to season.! Agroforestry- intercropping trees with vegetables.! Contour plowing- plowing and harvesting parallel to the land to prevent erosion.

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59 No-till Agriculture! No-till agriculture- helps to stop soil degradation by leaving crop residues in the fields and not tilling the land after each harvest.

60 Organic Agriculture! Organic agriculture- production of crops without the use of synthetic pesticides or fertilizers.

61 Solutions Organic Farming Improves soil fertility Reduces soil erosion Retains more water in soil during drought years Uses about 30% less energy per unit of yield Lowers CO 2 emissions Reduces water pollution from recycling livestock wastes Eliminates pollution from pesticides Increases biodiversity above and below ground Benefits wildlife such as birds and bats Fig , p. 302

62 Failures of Organic Farming Unfavorable climate reduces cash crop because there are no genetically modified varieties used (drives the consumer cost up) Global warming and increased deforestation of rain forests are reducing precipitation in critical areas, thereby requiring increased irrigation use (drives consumer cost up) No fertilizers/pesticides used so the crop is more susceptible to damage and disease (drives consumer cost up) Basic Economics if demand is low, prices are high! Winds carry genetically modified seed and pesticides onto organically farmed lands (Monsanto).

63 Integrated Pest Management! Integrated pest management- using a variety of techniques designed to minimize pesticide inputs.! Crop rotation! Intercropping! Planting pest resistant crop varieties! Creating habitats for predators! Limited use of pesticides

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