Soil

1. Soil Pages 223-248

2. The changing face of agriculture 10,000 years ago, people in different cultures began to raise plants for food and to domesticate animals Agriculture: practice of raising crops and livestock for human use and consumption Cropland: land used to raise plants for human use Rangeland: land used for grazing livestock Land devoted to agriculture now covers 38% of Earth’s land

3. The changing face of agriculture Traditional agriculture: uses human and animal power Hand tools, simple machines Polyculture: different crops are planted in one field Industrial agriculture: uses large-scale machines and fossil fuels to boost yields Also uses irrigation, fertilizers, and pesticides Monoculture: planting a single, genetically similar crop More efficient but reduces diversity, is disease prone Narrows the human diet Used in industrial agriculture

4. Industrialized Crop Production Causes Soil Erosion • Industrialized agriculture, high-input agriculture (intensive) produces 80% of world’s food supply • Uses heavy equipment and large amounts of fossil fuels, water, commercial fertilizers, pesticides, and financial capital. • Primarily monocultures – single crop in one area. • Goal is to steadily increase crop yield, Ex Corn

5. The effects of industrialized agriculture Industrial agriculture has allowed food production to keep pace with population growth But it has many bad environmental and social effects Benefits: increases crop yields while reducing pressure to develop natural areas for new farms Drawbacks: water, fossil fuels, fertilizers, pesticides worsen pollution, erosion, and desertification Requires far more energy than traditional methods Displaces low-income farmers who can’t afford the technology, forcing them to move to cities

6. Sustainable agriculture Suitable farmland is disappearing We must improve the efficiency of production It is better to raise animals and crops that pollute less, require less fuels, and have less impact on natural systems Sustainable agriculture: maintains healthy soil, clean water, and genetic diversity Treats agricultural systems as ecosystems Low-input agriculture: uses smaller amounts of Pesticide, fertilizers, growth hormones, antibiotics, water, and fossil fuels than industrial agriculture

7. Regional differences in soils affect agriculture In rainforests, rain leaches minerals and nutrients, reducing their accessibility to roots Rapid decomposition of leaf litter results in a thin topsoil layer with little humus Farming quickly depletes the soil’s fertility Swidden agriculture: traditionally used in tropical areas After cultivation, a plot is left to regrow into forest Temperate prairies have lower rainfall and less nutrient leaching, resulting in higher fertility

8. Differences in regional agriculture Swidden agriculture is not sustainable at high population densities Fertile prairies can be farmed repeatedly if protected

9. The Dust Bowl In late 1800 and early 1900, farmers and ranchers: Grew wheat, grazed cattle Removed native grasses Dust Bowl: 1930s drought and erosion caused “black blizzards” of sand Thousands of farmers left their land Relied on governmental help to survive

10. The Soil Conservation Service (SCS) Started in 1935 by the Congress, the SCS works with farmers to develop conservation plans for farms The SCS is now named the Natural Resources Conservation Service Other countries started their own conservation agencies No-till farming in Argentina, Brazil, and Paraguay Grassroots organizations helped by agronomists and government extension agents

11. Agricultural subsidies affect soil degradation • Theoretically, the market should discourage farmers and ranchers from degrading the land • But degradation is slow, and farmers can’t afford to lose money • Many governments spend billions to subsidize agriculture • 20% of a U.S. farmer’s income comes from subsidies • Pros of subsidies: protect farmers from uncertain weather • Cons of subsidies: encourage farming of vulnerable land • Producing more food than needed, driving prices down • Farmers should buy insurance against losses

12. Seed banks conserve wild genes Industrial agriculture’s use of genetically similar crops has led to efforts to conserve wild relatives of crops Wild crops contain genes will will need in the future Seed banks: institutions that store seed types Seeds are collected, stored, and periodically planted Wild crops must not be allowed to interbreed with genetically modified crops To prevent introduction of GM crops into wild populations

13. The Green Revolution increased yields Green revolution: drastically increased food through new Technology Crop varieties Farming practices Spread to the developing world in the 1940s Wheat, rice, corn Norman Borlaug won the Nobel Peace Prize for his work

14. U.S. programs promote soil conservation • Conservation Reserve Program (1985): farmers are paid to put highly erodible land in conservation reserves • Trees and grasses are planted instead of crops • Each dollar spent saves 1 ton of topsoil • Generates income for farmers • Improves water quality and provides habitat • $1.8 billion/yr protects 30–40 million acres • The 2008 Farm Bill limits protection to 32 million acres • But funds 14 other programs • International agencies also promote sustainable agriculture

15. Sustainable approaches to irrigation Match crops and climate Don’t plant water-guzzling crops in dry areas Plant beans or wheat, not rice Subsidies make irrigation water artificially cheap Drip irrigation delivers water directly to plants Drip irrigation works best on smaller plots with perennial plants (fruit trees)

16. Fertilizers boost yields Fertilizers: substances containing essential nutrients to enhance crop production Inorganic fertilizers: mined or synthetically manufactured mineral supplements Organic fertilizers: the remains or wastes of organisms Manure, crop residues, fresh vegetation (green manure) Compost: produced when decomposers break down organic matter

17. Inorganic fertilizers cause problems Inorganic fertilizers have boosted production But also severely pollute Leaching and runoff of inorganic fertilizers causes: Groundwater contamination Dead zones in water systems Air pollution from evaporated nitrates Inorganic fertilizer use has skyrocketed worldwide

18. Sustainable fertilizers • Sustainable approaches to fertilizing delivers nutrients directly to plant roots and avoids overapplication • Add fertilizers to drip irrigation water • No-till or low-till systems inject fertilizers with seeds • Monitor soil nutrients and add only when they are low • Strips of vegetation along field edges and streams capture nutrient runoff • Organic fertilizers add nutrients and organic matter • Improving soil structure, nutrient and water retention • Integrate inorganic and organic fertilizer systems

19. Pesticides control pests • Pest: any organism that damages valuable crops • Weed: any plant that competes with crops • Pests and weeds especially threaten monocultures • Pesticides: poisons that target pest organisms • Insecticides kill insects, herbicides kill plants, and fungicides kill fungi • 75% of pesticides are applied to agricultural land • Exposure to synthetic pesticides can cause health problems for humans and other organisms • Pesticides also kill many nontarget organisms

20. Pests evolve resistance to pesticides • Pesticides lose effectiveness as pests evolve resistance • Individuals that can metabolize and detoxify a pesticide survive and pass these genes to their offspring • As the population increases, pesticides lose their effectiveness • Pesticide treadmill: chemists increase the toxicity of pesticides to compete with resistant pests • Many species (green peach aphid, diamondback moth) have evolved resistance to multiple chemicals

21. Evolution of pesticide resistance Over 586 species are resistant to 330 insecticides Hundreds of weeds and plant diseases have evolved resistance to herbicides and pesticides

22. Biological control (biocontrol) • Biological control: uses a pest’s predators or diseases to control the pest • But organisms can’t be easily controlled • Organisms can harm nontargets • Example: introduced cactus moths eat rare Florida cacti • Biocontrol must be carefully planned and regulated

23. Integrated pest management (IPM) IPM in Indonesia increased rice yields 13% and saved $179 million/yr in phased-out subsidies • Techniques to suppress pests include: * Biocontrol * Habitat alteration * Chemicals, if necessary * Crop rotation * Population monitoring * Transgenic crops * Alternative tillage methods * Mechanical pest removal

24. Pollinators are beneficial “bugs” • Not all insects are pests; some are absolutely vital • Over 800 cultivated plants rely on pollinators • Pollination: male plant sex cells fertilize female sex cells • Flowers are evolutionary adaptations to attract pollinators • Nectar, pollen, sweet smells, bright colors • U.S. bees provide $3 billion/year in pollination services, but parasitic mites decimated populations • Beekeepers were driven to financial ruin

25. Conservation of pollinators is vital Populations of bees further plummeted in 2006 • Colony collapse disorder: entire beehives have died • One-third of all U.S. honeybees die/year • Unknown causes—Insecticides? Parasites? Stress?

26. Genetically modified food • Despite the Green Revolution, relentless population growth demands more innovation to feed us • Scientists alter genes of organisms • Crop plants and livestock • Genetically modified organisms enhance nutrition and agricultural efficiency • But the risks are not well understood, leading to anxiety and protest from: • Consumer advocates, small farmers, environmentalists, critics of big business

27. Genetically modified organisms • Genetic engineering:laboratory manipulation of genetic material • Add, delete, modify DNA • Genetically modified (GM) organisms: organisms that have been genetically engineered using … • Recombinant DNA: DNA created from multiple organisms

28. Biotechnology is impacting our lives • The goal of genetic engineering: put genes that code for desirable traits (rapid growth, nutrition, etc.) • Into organisms lacking those traits • Transgenic organism: an organism that contains DNA from another species • Transgenes:the genes that have moved between organisms • Biotechnology: the application of biological science to create products derived from organisms • It has created medicines, cleaned up pollution, dissolved blood clots, and made better food

29. Some genetically modified foods

30. Selective breeding vs. genetic engineering Selective 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 to change organisms Genetic engineering: mixes genes of different species (e.g., spiders and goats) Works with genetic material in the lab Directly creates novel combinations of genes Resembles the process of mutation

31. Biotechnology is changing our world 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, and cotton are genetically modified

32. What are the impacts of GM crops? As GM crops expanded, citizens, scientists, and policymakers became concerned that: GM crops could have adverse impacts on human health Pests could evolve resistance and become “superpests” and “superweeds” GM crops could harm nontarget organisms GM crops could interbreed with closely related wild plants Millions of Americans eat GM foods without obvious harm But it is too early to dismiss concerns

33. Some impacts of GM crops Mixed results on pesticide use Insecticide use declined, but herbicide use increased GM foods can advance sustainable agriculture Grown with no-till farming Drought resistant and high-yielding Problems with GM foods: Expensive Little incentive to develop crops for small-scale farmers

34. Genetic engineering is profit driven This “gene revolution” is driven by financial interests of corporations A few large agribiotech corporations dominate the world’s food supply Europeans want GM foods labeled U.S. consumers have mostly accepted GM crops Brazil, India, and China are aggressively pursuing GM crops We should follow the precautionary principle and proceed with caution on GM foods

35. Consumption of animal products is growing As wealth and commerce increase, so does consumption of meat, milk, and eggs Since 1950, global meat production has increased fivefold, and per capita meat consumption has doubled As developing nations become wealthier, meat consumption will double by 2050

36. Our food choices are also energy choices Eating meat is far less energy efficient than eating crops 90% of energy is lost from one trophic level to the next Some animals convert grain into meat more efficiently than others

37. Resources needed for livestock production • Land and water are needed to raise food for livestock • Eggs and chicken meat require the least • Producing beef requires the most When we choose what to eat, we choose how we use resources

38. Feedlot agriculture Feedlots (factory farms): also called concentrated animal feeding operations (CAFOs) Huge warehouses or pens deliver food to animals living at extremely high densities House over half of the world’s pork and most of its poultry Most U.S. meat is raised in feedlots, which use liberal amounts of antibiotics to control disease

39. Pros and cons of feedlot agriculture It allows greater production of affordable meat It reduces grazing impacts on the land 45% of the world’s grain is fed to livestock Endangering food security for the world’s poor Feedlots produce huge amounts of manure and urine Can pollute surface water and groundwater Crowded housing causes outbreaks in disease Heavy use of antibiotics More greenhouse gases (CO2, methane, nitrous oxides) than automobile emissions

40. We raise seafood with aquaculture World wild fish populations are plummeting Increased demand and technology • Aquaculture: raising aquatic organisms in a controlled environment • Open-water pens or land-based ponds • The fastest-growing type of food production • Most widespread in Asia

41. Aquaculture’s benefits and drawbacks Benefits: Reduces pressure on overharvested wild fish Uses fewer fossil fuels, is safer, and produces more fish than commercial fishing Drawbacks: Lots of waste produced Uses grain, which affects food supplies for people Fish meal is made from wild ocean fish Escaped fish introduce disease or outcompete wild fish

42. Organic agriculture • Sustainable agriculture keeps high crop yields, minimizes resource use, and decreases environmental impacts • Organic agriculture: uses no synthetic fertilizers, insecticides, fungicides, or herbicides • Organic Food Production Act (1990) establishes national standards for organic products • The USDA issued criteria in 2000 by which food could be labeled organic • California, Washington, Texas passed stricter guidelines for labeling

43. Benefits and costs of organic farming Farmers have lower input costs, enhanced income, reduced chemical pollution and soil degradation Obstacles include the risks and costs of switching to new methods The main obstacle to consumers is the higher price But many are willing to pay the price Worldwide, sales surpassed $54 billion

44. Organic agriculture is booming U.S. land devoted to organic agriculture has quadrupled since the mid-1990s U.S. consumers spent $24.8 billion on organic food in 2009

45. Governments can support organic farming The U.S. 2008 Farm Bill gives $112 million over 5 years for organic agriculture It helps defray certification costs In 1993, the European Union started supporting farmers financially during conversion to organic farming Reduced inputs and higher market prices will make it as profitable as conventional methods

46. Locally supported agriculture is growing Sustainable agriculture reduces fossil fuel use from long-distance transport of products The average U.S. food product travels 1,400 miles Farmers’ markets: provide fresh, locally grown food Provide organic items and unique local varieties Community-supported agriculture(CSA) Consumers pay farmers in advance for produce Consumers get fresh food Farmers get a guaranteed income

47. Sustainable agriculture: a roadmap for the future • Sustainable agriculture mimics natural ecosystems • They operate in cycles and are internally stabilized by negative feedback loops • Agricultural systems can be integrated with the surrounding ecosystems • Reducing environmental impacts from food production • Making agriculture sustainable is crucial for all of us

48. Biofuels can affect food supplies • Biofuels: fuels derived from organic materials • Replace petroleum in engines • Ethanol: a biofuel derived from corn • The main biofuel in the U.S. • 2007 subsidies doubled U.S. production • Use of corn for biofuel reduced corn supplies • Food prices increased • Farmers sold corn for ethanol, not food • Farmers planted biofuels, not food crops • Riots erupted in many nations

49. Conclusion Industrialized agriculture has had substantial negative environmental consequences To support 9 billion humans, we must shift to sustainable agriculture to prevent further land degradation Biological pest control, organic agriculture Pollinator protection, preservation of native crops Aquaculture Careful, responsible genetic modification of food

50. Case Studies MEDC- (Dustbowl 1930s) LEDC- India see article