Transcript Chapter 10
ENVIRONMENTAL SCIENCE 13e CHAPTER 10: Food, Soil, and Pest Management Core Case Study: Is Organic Agriculture the Answer? (1) • Organic agriculture as a component of sustainable agriculture • Certified organic farming: – Less than 1% of world cropland – 0.1% of U.S. cropland – 6-18% in many European countries Core Case Study: Is Organic Agriculture the Answer? (2) • Many environmental advantages over conventional farming • Requires more human labor • Organic food costs 10-75% more than conventionally grown food • Cheaper than conventionally grown food when environmental costs are included 10-1 What Is Food Security and Why Is It So Difficult to Attain? • Concept 10-1A Many of the poor have health problems from not getting enough food, while many people in affluent countries suffer health problems from eating too much. • Concept 10-1B The greatest obstacles to providing enough food for everyone are poverty, political upheaval, corruption, war, and the harmful environmental effects of food production. Poor Lack Sufficient Food • Enough food for all – but in developing countries 1/6 do not get enough to eat • Poverty – Food insecurity – Chronic hunger – Poor nutrition • Food security Nutrition • Macronutrients and micronutrients • Chronic undernutrition • Malnutrition – Low-protein, high-carbohydrate diet – Physical and mental health problems – 6 million children die each year • Vitamin and mineral deficiencies Overnutrition • Too many calories, too little exercise, or both • Similar overall health outlook as undernourished • 1.6 billion people eat too much • 66% of American adults overweight, 34% obese – Heart disease and stroke – Type II diabetes and some cancers 10-2 How Is Food Produced? • Concept 10-2 We have used highinput industrialized agriculture and lower-input traditional methods to greatly increase supplies of food. Where We Get Food (1) • Major sources: – Croplands – Rangelands, pastures, and feedlots – Fisheries and aquaculture Where We Get Food (2) • Since 1960 tremendous increase in food supply – Better farm machinery – High-tech fishing fleets – Irrigation – Pesticides and fertilizers – High-yield varieties Only a Few Species Feed the World • Food specialization in small number of crops makes us vulnerable • 14 plant species provide 90% of world food calories • 47% of world food calories comes from rice, wheat, and corn Industrialized Agriculture (1) • High-input agriculture – monocultures • Large amounts of: – Heavy equipment – Financial capital – Fossil fuels – Water – Commercial inorganic fertilizers – Pesticides • Much food produced for global consumption Industrialized Agriculture (2) • Plantation agriculture primarily in tropics – Bananas – Sugarcane – Coffee – Vegetables – Exported primarily to developed countries Traditional Agriculture • 2.7 billion people in developing countries • Traditional subsistence agriculture • Traditional intensive agriculture • Monoculture • Polyculture Science Focus: Soil is the Base of Life on Land (1) • Soil composed of – Eroded rock – Mineral nutrients – Decaying organic matter – Water – Air – Organisms Science Focus: Soil is the Base of Life on Land (2) • Soil is a key component of earth’s natural capital • Soil profile – O Horizon – A horizon – B horizon – C horizon Green Revolution • Three-step green revolution – Selectively bred monocultures – High yields through high inputs – fertilizer, pesticides, and water – Multiple cropping • Second green revolution – fast-growing dwarf varieties of wheat and rice • 1950-1996 – world grain production tripled Case Study: Industrialized Food Production in the U.S. • Industrialized farming agribusiness • Increasing number of giant multinational corporations • ~10% U.S. income spent on food • Subsidized through taxes Case Study: Brazil – The World’s Emerging Food Superpower • Ample sun, water, and arable land • EMBRAPA – government agricultural research corporation • 2-3 crops per year in tropical savanna • Lack of transportation impeding further growth as food exporter Production of New Crop Varieties • Traditional – Crossbreeding – Artificial selection – Slow process • Genetic engineering – Genetic engineering • >75% of U.S. supermarket food genetically engineered Meat Production • Meat and dairy products are good sources of protein • Past ~60 years meat production up five-fold • Half of meat from grazing livestock, other half from feedlots Fish and Shellfish Production Have Increased Dramatically • Aquaculture – 46% of fish/shellfish production in 2006 – Ponds – Underwater cages – China produces 70% of world’s farmed fish 10-3 What Environmental Problems Arise from Food Production? • Concept 10-3 Future food production may be limited by soil erosion and degradation, desertification, water and air pollution, climate change from greenhouse gas emissions, and loss of biodiversity. Soil Erosion • • • • • • Flowing water Wind Soil fertility declines Water pollution occurs Some natural Much due to human activity Drought and Human Activities • Desertification • Combination of prolonged draught and human activities • 70% of world’s drylands used for agriculture • Will be exacerbated by climate change Effects of Irrigation • Leaves behind salts in topsoil • Salinization – Affects 10% of global croplands • Waterlogging – Attempts to leach salts deeper but raises water table – Affects 10% of global croplands Limits to Expanding Green Revolutions • High-inputs too expensive for subsistence farmers • Water not available for increasing population • Irrigated land per capita dropping • Significant expansion of cropland unlikely for economic and ecological reasons Industrialized Food Production Requires Huge Energy Inputs • Mostly nonrenewable oil – Run machinery – Irrigation – Produce pesticides – Process foods – Transport foods • In U.S., food travels an average of 1,300 miles from farm to plate Controversies over Genetically Engineered Foods • • • • Potential long-term effects on humans Ecological effects Genes cross with wild plants Patents on GMF varieties Food and Biofuel Production Lead to Major Losses of Biodiversity • Forests cleared • Grasslands plowed • Loss of agrobiodiversity – Since 1900, lost 75% of genetic diversity of crops – Losing the genetic “library” of food diversity Industrial Meat Production Consequences • • • • • Uses large amounts of fossil fuels Wastes can pollute water Overgrazing Soil compaction Methane release: greenhouse gas Aquaculture Problems • Fish meal and fish oil as feed – Depletes wild fish populations – Inefficient – Can concentrate toxins such as PCBs • Produce large amounts of waste 10-4 How Can We Protect Crops from Pests More Sustainably? • Concept 10-4 We can sharply cut pesticide use without decreasing crop yields by using a mix of cultivation techniques, biological pest controls, and small amounts of selected chemical pesticides as a last resort (integrated pest management). Nature’s Pest Control • Polycultures – pests controlled by natural enemies • Monocultures and land clearing – Loss of natural enemies – Require pesticides Increasing Pesticide Use • • • • • Up 50-fold since 1950 Broad-spectrum agents Selective agents Persistence Biomagnification – some pesticides magnified in food chains and webs Advantages of Modern Pesticides • • • • • • Save human lives Increase food supplies Increase profits for farmers Work fast Low health risks when used properly Newer pesticides safer and more effective Disadvantages of Modern Pesticides • Pests become genetically resistant • Some insecticides kill natural enemies • May pollute environment • Harmful to wildlife • Threaten human health • Use has not reduced U.S. crop losses Laws Regulate Pesticides • Environmental Protection Agency (EPA) • United States Department of Agriculture (USDA) • Food and Drug Administration (FDA) • Congressional legislation • Laws and agency actions criticized Individuals Matter: Rachel Carson • Biologist • DDT effects on birds • 1962: Silent Spring makes connection between pesticides and threats to species and ecosystems Science Focus: Ecological Surprises • Dieldrin killed malaria mosquitoes, but also other insects • Poison moved up food chain – Lizards and then cats died – Rats flourished – Operation Cat Drop • Villagers roofs collapsed from caterpillars – natural insect predators eliminated Alternatives to Pesticides • • • • • Fool the pest Provide homes for pest enemies Implant genetic resistance Natural enemies Pheromones to trap pests or attract predators • Hormones to disrupt life cycle Integrated Pest Management • Evaluate a crop and its pests as part of ecological system • Design a program with: – Cultivation techniques – Biological controls – Chemical tools and techniques – Can reduce costs and pesticide use without lowering crop yields 10-5 How Can We Improve Food Security? • Concept 10-5 We can improve food security by creating programs to reduce poverty and chronic malnutrition, relying more on locally grown food, and cutting waste. Use Government Policies to Improve Food Production and Security • Control food prices – Helps consumers – Hurts farmers • Provide subsidies to farmers – Price supports, tax breaks to encourage food production – Can harm farmers in other countries who don’t get subsidies – Some analysts call for ending all subsidies Reducing Childhood Deaths • $5–$10 annual per child would prevent half of nutrition-related deaths • Strategies – Immunization – Breast-feeding – Prevent dehydration from diarrhea – Vitamin A – Family planning – Health education for women 10-6 How Can We Produce Food More Sustainably? • Concept 10-6 More sustainable food production involves reducing overgrazing and overfishing, irrigating more efficiently, using integrated pest management, promoting agrobiodiversity, and providing government subsidies only for more sustainable agriculture, fishing, and aquaculture. Reduce Soil Erosion (1) • • • • • Terracing Contour plowing Strip cropping Alley cropping Windbreaks Reduce Soil Erosion (2) • • • • • Shelterbelts Conservation-tillage farming No-till farming Minimum-tillage farming Retire erosion hotspots Government Intervention • Governments influence food production – Control prices – Provide subsidies – Let the marketplace decide • Reduce hunger, malnutrition, and environmental degradation – Slow population growth – Sharply reduce poverty – Develop sustainable low-input agriculture Case Study: Soil Erosion in the United States • Dust Bowl in the 1930s • 1935 Soil Erosion Act – Natural Resources Conservation Service – Helps farmers and ranchers conserve soil • One-third topsoil gone – Much of the rest degraded • Farmers paid to leave farmland fallow Restoring Soil Fertility • Organic fertilizers – Animal manure – Green manure – Compost • Crop rotation uses legumes to restore nutrients • Inorganic fertilizers – pollution problems Sustainable Meat Production • Shift to eating herbivorous fish or poultry • Eat less meat • Vegetarian Shift to More Sustainable Agriculture • • • • Organic farming Perennial crops Polyculture Renewable energy, not fossil fuels Six Strategies for Sustainable Agriculture 1. Increase research on sustainable agriculture 2. Set up demonstration projects 3. International fund to help poor farmers 4. Establish training programs 5. Subsidies only for sustainable agriculture 6. Education program for consumers Science Focus: The Land Institute and Perennial Culture • Polycultures of perennial crops • Live for years without replanting • Better adapted to soil and climate conditions • Less soil erosion and water pollution • Increases sustainability Three Big Ideas from This Chapter - #1 About 925 million people have health problems because they do not get enough to eat and 1.6 billion people face health problems from eating too much. Three Big Ideas from This Chapter - #2 Modern industrialized agriculture ha a greater harmful impact on the environment than any other human activity. Three Big Ideas from This Chapter - #3 More sustainable forms of food production will greatly reduce the harmful environmental impacts of current systems while increasing food security and national security for all countries.