SOIL & AGRICULTURE

1. SOIL&AGRICULTURE

2. Humus – broken down organic material • Minerals – come from the bedrock • Sand • Silt • Clay • Weathering – the process of breaking down rock

3. Plants need topsoil • Topsoil forms slowly • Biological process • Without it, plants don’t grow well • Nutrients • Symbiotic organisms • Water holding capacity • Air access

4. Erosion – loss of topsoil • Bare soil gets lost – wind and water

5. Erosion – loss of topsoil • Vegetated soil is conserved • Different farming methods cause different amounts of erosion • How much soil is exposed?

6. Fertilizer replaces nutrients in used-up soil • Tilling and poor crop rotation cause nutrient depletion • Nutrients can be replaced with fertilizer

7. Eutrophication • Excess nutrients run into streams and on to the ocean • Causing algae blooms • Which cause eutrophication • Decomposers eating the dead algae use up all the O2

8. Agriculture

9. We produce our food with technology and fossil fuels Diesel, irrigation, fertilizer, pesticides, cultivating more land, genetic engineering Today, soils are in decline and most arable land is already farmed Today, we are producing enough food for all By 2050, we will have to feed about 9 billion people

10. Undernutrition and food security • 1 billion people do not have enough to eat • Undernutrition = people receive fewer calories than their minimum requirements • Due to 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

11. Food security 15% of the world’s population is hungry

12. Overnutrition and malnutrition • Overnutrition = receiving too many calories each day • Developed countries have abundant, cheap junk food, and people lead sedentary lives • In the U.S., 32.5% of adults are obese • Worldwide, over 400 million people are obese • Malnutrition = a shortage of nutrients the body needs • The diet lacks adequate vitamins and minerals • Can lead to diseases

13. The “green” revolution • Started in the 1940s • Techniques to increase crop output per unit area of cultivated land with fossil fuels • Also uses new crop plants • Breeding • GM

14. The Green Revolution • HYV = High yeild varieties • Outperform traditional varieties if they have chemical fertilizer and pesticides and lots of water • Rich farmers with lots of land benefited • Poor farmers were driven off the land into cities Today, yields are declining in most Green Revolution areas

15. Green revolution: Environmental consequences From 1900-2000, cultivated area increased 33% while energy inputs increased 8000%. Intensification of agriculture causes environmental harm: • Pollution from synthetic fertilizers • Pollution from chemical pesticides • Water depleted for irrigation • Fossil fuels used for heavy equipment

16. Monocultures • Intensified agriculture meant monocultures, vast expanses of a single crop, farmed with diesel power. • economically efficient and increases output, but increases risk of catastrophic failure (“all eggs in one basket”). Wheat monoculture in Washington

17. Crop diversity • Monocultures have devastated crop diversity and contributed to a narrowing of the human diet. • 90% of all human food now comes from only 15 crop species and 8 livestock species. (down from thousands)

18. Seed banks preserve seeds, crop varieties Seed banks are living museums of crop diversity, saving collections of seeds and growing them into plants every few years to renew the collection. Careful hand pollination helps ensure plants of one type do not interbreed with plants of another.

19. We have thousands of pesticides • 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 • 400 million kg (900 million lb) of pesticides are applied in the U.S. each year • 75% of this is applied to agricultural land • $32 billion/year is spent on pesticides worldwide

20. Pests evolve resistance to pesticides(the “pesticide treadmill”) • Pesticides gradually become less effective, because pests evolve resistance to them. • The immune ones then breed and the next generation is ALL IMMUNE • So, it’s an arms race

21. Pests evolve resistance to pesticides 2. Pesticide applied. 1. Pests attack crop.

22. Pests evolve resistance to pesticides, continued 4. Survivors breed and produce pesticide-resistant population. 3. All pests except a few with innate resistance are killed.

23. Pests evolve resistance to pesticides, continued 6. Has little effect. More-toxic chemicals must be developed. 5. Pesticide aplied again.

24. Pesticides are toxic to us too... • The Centres for Disease Control (U.S.) tested 9,000 people for 34 different pesticides. The average American had 13 pesticides in his or her body. • The levels of toxins found in infants is sometimes 2-3 times higher than levels that cause disease or dysfunction in lab animals. • Toxin levels are up to 7X higher than the parents. • Many pesticides affect our brain and hormones • p. 388 http://blogs.scientificamerican.com/observations/2012/05/01/common-pesticide-disturbs-the-brains-of-children/

25. Biological control • Alternative pest control • Biological control (biocontrol) = uses a pest’s predators to control the pest • Reduces pest populations without chemicals

26. Biological control • Biocontrol has had success stories. • Bacillus thuringiensis (Bt) = soil bacterium that kills many insects Cactus moth, Cactoblastis cactorum (above), was used to wipe out invasive prickly pear cactus in Australia.

27. But biocontrol is risky • Most biocontrol agents are introduced from elsewhere. • Some may turn invasive and become pests themselves! • Wasps and flies brought to Hawaii to control crop pests are parasitizing native caterpillars in wilderness areas. • Cane toads brought to Queensland, Australia to control the cane beetle spread and are threatening native species. • Knapweed – Urophora – Mice – Hanta • Snake – Mongoose – Bird – Rabies

28. Integrated pest management (IPM) Combines biocontrol, chemical, and other methods May involve: • Biocontrol • Close population monitoring • Habitat alteration • Crop rotation • Transgenic crops • Alternative tillage methods • Mechanical pest removal • Chemicals, if necessary

29. Pollination • Process of plant reproduction: male pollen meets female egg cells • Animals transfer pollen to pollinate female plants • Pollinating insects are necessary for 800 of our crop species. -Other pollinators include bats and hummingbirds.

30. Pollinator conservation European honeybees commercially used to pollinate crop plants have been hit hard by parasites lately: CCD So it’s important to conserve native bees (e.g. mason bees) and other insects that pollinate crop plants naturally. Overuse of pesticides can backfire by killing beneficial pollinators, e.g. colony collapse disorder.

31. Genetic engineering • Genetic engineering(GE) = directly manipulating an organism’s genetic material in the lab by adding, deleting, or changing segments of its DNA • Genetically modified (GM) organisms = genetically engineered using recombinant DNA technology • Recombinant DNA= DNA patched together from multiple organisms

32. Transgenes and biotechnology • Genetic engineering is different from traditional breeding • Can mix genes of wildly different species • Traditional breeding involves artificial selection • mating individuals of the same species with favorable traits.

33. Some GM foods

34. Some GM foods

36. Prevalence of GM foods • Although many early GM crops ran into bad publicity or other problems, biotechnology is already transforming the U.S. food supply. • Most of U.S. soybeans, corn, cotton and canola are now genetically modified strains.

37. 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

38. Scientific concerns about GM crops • Are there health risks for people? • Can transgenes escape into wild plants, pollute ecosystems, harm organisms? • Can pests evolve resistance to GM crops just as they can to pesticides? • Can transgenes jump from crops to weeds and make them into “superweeds”? • Can transgenes get into traditional native crops and ruin their integrity?

39. The GM debate involves ethics • With increasing use, people are forced to use GM products, or go to special effort to avoid them • Multinational corporations threaten the small farmer • Research is funded by corporations that profit if GM foods are approved for use • GM crops have not eradicated hunger • GM crops do not focus on increased nutrition, drought tolerance, etc. The GM industry is driven by market considerations driven by financial interests of corporations

40. Animal agriculture: Livestock and poultry Consumption of meat has risen faster than population over the past several decades.

41. Feedlot agriculture • Increased meat consumption has led to animals being raised in feedlots (factory farms - also called Concentrated Animal Feeding Operations or CAFOs), huge pens that deliver energy-rich food to animals housed at extremely high densities.

42. Feedlot agriculture: Environmental impacts • Immense amount of waste produced, polluting air and water nearby • Intense usage of chemicals (antibiotics, steroids, hormones), some of which persist in environment, meat, milk, eggs, etc.

43. There ARE alternatives

44. Grain feed input for animal output This is if these animals are fed on grain. This is standard in feedlots. (Alcohol also uses a lot of grain)

45. Land and water input for animal output Some animal food products can be produced with less input of land and water than others. Eating lower on the food chain helps reduce your ecological footprint and feed more people.

46. Sustainable agriculture • Agriculture that can be practiced the same way far into the future • Does not deplete soils faster than they form. • Does not reduce healthy soil, clean water, and genetic diversity essential for long-term crop and livestock production. • Low-input agriculture= small amounts of pesticides, fertilizers, water, growth hormones, fossil fuel energy, etc. • Organic agriculture= no synthetic chemicals used. Rely on biocontrol, composting, etc.

47. Organic farming Studies have shown organic farm fields to have deeper topsoil and greater earthworm activity, both signs of healthy soil.

48. Organic farming • Small percent of market, but is growing fast • 4.2% of U.S. market, but growing fast • Organic produce: Advantages for consumers: healthier; environmentally better; tastes better! • Disadvantages for consumers: less uniform and appealing-looking; more expensive

49. Permaculture (Ecological Farming) • Permaculture is a way of desinging farms to function like ecosystems • There is no waste • Grow a wide diversity of crops • Can be zero pesticide use, zero fertilizer input • Can REGENERATE wasted land

50. Locally supported agriculture • Through community-supported agriculture, consumers pay farmers for a share of their yield. Farmers’ markets have become more widespread.