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Published byAlannah Robinson Modified over 8 years ago
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Chapter 10 Topics: Feeding a growing human population The Green Revolution Preserving crop diversity Pest management Pollination Genetically modified food Feedlot agriculture Aquaculture Sustainable agriculture
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Trends in food production Food production exceeds population growth We produce food through technology Fossil fuels, irrigation, fertilizer, pesticides, cultivating more land, genetic engineering Today, soils are in decline and most arable land is already farmed
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Under-nutrition 1 billion people do not have enough to eat Under-nutrition = people receive fewer calories than their minimum requirements Caused by economics, politics, conflict, and inefficiencies in distribution Most undernourished live in developing nations but 36 million Americans are “food insecure” Food security = guarantee of an adequate, safe, nutritious, and reliable food supply
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Over-nutrition Over-nutrition = people receive too many calories Developed countries have abundant, cheap junk food, and people lead sedentary lives In the U.S., 25% of adults are obese Worldwide, over 400 million people are obese
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Malnutrition Malnutrition = people receive fewer nutrients than the body needs – the diet lacks vitamins/minerals Malnutrition leads to diseases Kwashiorkor = diet lacks protein or essential amino acids Occurs when children stop breast-feeding Bloated stomach, mental and physical disabilities
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The Green Revolution Mid- to late 20 th century – Norman Borlaug The use of new methods and technologies to increase the yield per acre for primary grain crops (wheat, corn, rice) Depended on lots of: Synthetic fertilizers Chemical pesticides Irrigation Machinery
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Looking back From 1900 to 2000, cultivated area increased 33% while energy inputs increased 80 times Positive effects on the environment Prevented some deforestation and land conversion Preserved biodiversity and ecosystems Negative effects on natural resources Pollution, erosion Salinization, desertification
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India’s experience Intensified agriculture saved millions from starvation India became a grain exporter Rich farmers with lots of land benefited Poor farmers were driven off the land into cities
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Narrowing our diet The Green Revolution narrowed the human diet: 90% of our food comes from 15 crop and 8 livestock species Market forces discourage diversity in appearance, preference for uniform, standardized food
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Monocultures Monocultures, a legacy of the Green Revolution Large plantings of a single crop Sometimes a single genetic variety! Can be cost-efficient and increase output Significantly reduce biodiversity Susceptible to pests and diseases
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Preserving crop diversity Preserving native variants can help to protect against crop failure Wild relatives of crops contain genes that can provide resistance to disease and pests Seed banks = institutions that collect, store, and periodically plant seeds to preserve genetic diversity
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Pesticides Our heavy use of pesticides and the issues this creates are another legacy of the Green Revolution Pest = any organism that damages valuable crops Weed = any plant that competes with crops Pesticides = poisons that target pest organisms Insecticides = kill insects Herbicides = kill plants Fungicides = kill fungi 900 million lbs of pesticides are applied each year 75% of this is applied to agricultural land $32 billion/year is spent on pesticides worldwide
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Issues with pesticides Pests become resistant to pesticides through the processes of evolution The “pesticide treadmill” – an escalating cycle of increasing chemical toxicity and ever more resistant pests 556 insect species are resistant to 300 pesticides Pesticides also kill non-target organisms Including predators and parasites of pests Pest populations become even harder to control
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Biological control of pests Biological control uses a pest’s predators to control the pest Cactus moths control prickly pear Weevils control water hyacinth Bacillus thuringiensis (Bt) a soil bacteria that kills many caterpillars and insect larvae
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Bio-control can backfire Risky to introduce an organism from a foreign ecosystem into a new ecological context The effects of an introduced species are unpredictable The agent may have “non-target” effects on the environment and surrounding economies Removing a bio-control agent is harder than halting pesticide use
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Integrated Pest Management (IPM) The use of multiple techniques to suppress pests: Biocontrol Chemicals, if necessary Population monitoring Habitat alteration Crop rotation Alternative tillage Mechanical pest removal
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The other side of insects We depend on insects to pollinate crops 800 crop species rely on insect pollinators Flowers are evolutionary adaptations to attract pollinators Conservation of pollinators is vital Bee populations have been plummeting Colony collapse disorder = entire beehives have vanished – causes as yet unknown Reducing or eliminating pesticide use and planting flowering plants will help preserve bees
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Biotechnology Biotechnology = the application of biological science to create products derived from organisms Biotechnology has created medicines, cleaned up pollution, and dissolved blood clots Biotechnology is now being applied to food, specifically through genetic engineering – laboratory manipulation of genetic material Genetically modified organisms (GMOs) engineered using recombinant DNA (genes from multiple organisms) Also called transgenic organisms and transgenes
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Traditional breeding vs GMOs Traditional breeding = changes organisms through selective breeding of the same or similar species Works with organisms in the field Genes come together on their own Uses the process of selection Genetically modified organisms = genes of different species are mixed Works with genetic material in the lab Directly creates novel combinations of genes Resembles the process of mutation
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A growing business… GM foods are a big business Most GM crops are herbicide and pesticide resistant Large-scale farmers grow crops more efficiently Most U.S. corn, soybeans, cotton, and canola are genetically modified
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The environmental pros and cons Benefits of genetically modified organisms: Reduced use of chemical insecticides Increased no-till farming Decreased irrigation, deforestation, land conversion Negatives of genetically modified organisms: Increased herbicide use affects health and habitats Some GM fields support less biodiversity The field is very new and questions about long-term human health and environmental effects remain
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Science, society, economics, ethics Science is only part of the GMO story People don’t like “tinkering” with the food supply As use grows, people are forced to use GM products, or go to special effort to avoid them Research is funded by corporations that profit if GM foods are approved for use Multinational corporations threaten the small farmer GM crops have not eradicated hunger, they do not focus on increased nutrition, drought tolerance, etc.
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Moving forward U.S. consumers have mostly accepted GM crops They don’t realize most food contains GM products Europeans demand that GM foods are labeled The U.S. sued the European Union before the World Trade Organization for hindering free trade Brazil, India, and China actively developing GM crops
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Animals as food As wealth and commerce increase, so does meat, milk, and egg consumption Since 1950, global meat production has increased fivefold and per capita meat consumption has doubled
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Food choices are energy choices Eating meat is less energy efficient than eating crops Eating at lower trophic levels feeds more people Some animals convert grain into meat more efficiently than others
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Food choices are resource choices Land and water are needed to raise food for livestock Producing eggs and chicken meat requires the least space and water Producing beef requires the most
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Feedlot agriculture High consumption leads to feedlot agriculture Feedlots animals raised in large warehouses or pens at high densities Concentrated Animal Feeding Operations (CAFOs) raise over half of the pork and most of the poultry
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On the one hand… Traditional agriculture keeps livestock on grasslands Feedlots reduced grazing impacts on the land Feedlot animals are fed grain grown on cropland One-third of the world’s cropland is fed to livestock Feedlot agriculture allows economic efficiency Greater production of food, necessary in countries with high meat consumption Manure can be applied to fields as fertilizer
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On the other hand… Feedlots produce huge amounts of manure and urine Causing eutrophication Waterborne pathogens sicken people Crowded, dirty housing causes outbreaks in disease Heavy use of antibiotics, hormones, heavy metals Chemicals are transferred to people Microbes evolve resistance to antibiotics Feedlots create air pollution Odors (ammonia) Greenhouse gases (CO 2, methane)
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Aquaculture Demand for animal proteins also affects fish Ocean fish populations are plummeting Aquaculture raising aquatic organisms in open-water pens or land- based ponds
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Current trends Aquaculture is growing rapidly, widespread in Asia Over 220 freshwater and marine species are grown Fastest-growing type of food production Provides ¾ of the world’s fish, ½ of the shellfish
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Benefits and drawbacks Reliable protein source Energy efficient Can be sustainable Reduces pressure on overharvested wild fish Antibiotics for disease Lots of biologic waste Uses grain Escaped GM fish outcompete wild fish BenefitsDrawbacks
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Sustainable agriculture Industrial agriculture may seem necessary but less- intensive agricultural methods are better Sustainable agriculture = does not deplete soil, pollute water, or decrease genetic diversity Low-input agriculture = uses smaller amounts of pesticide, fertilizers, growth hormones, water, and fossil fuels than industrial agriculture Organic agriculture = uses no synthetic fertilizers, insecticides, fungicides, or herbicides; relies on biological approaches
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Organic farming Organic Food Production Act (1990) establishes national standards for organic products The USDA issued criteria in 2000 by which food could be labeled organic Demand & production are increasing U.S. consumers spend $22.9 billion/year 1.8 million ha of land being organically farmed
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Benefits and obstacles More profitable in the long run – lower input costs, enhanced income, Farmers practice stewardship of the land – less chemical pollution, less soil degradation Addresses consumer concerns about pesticide’s health risks Risks/costs of switching to new methods Temporary loss of income The U.S. offers no financial support during the conversion Organic product cost more in the marketplace
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Locally supported agriculture Farmers’ markets = provide fresh, locally grown food Community-supported agriculture (CSA) Consumers pay farmers in advance Consumers get fresh food Farmers get a guaranteed income Local food has a smaller ecological footprint (lower transportation costs)
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Mimicking natural ecosystems Ecosystems operate in cycles Stabilized by negative feedback loops Small-scale Japanese farmers add ducks to rice fields Ducks eat weeds, insects, snails Their waste is fertilizer Their paddling oxygenates the water Fish and ferns provide food and habitat
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