1. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture prepared by Jay Withgott Scott Brennan Jay Withgott 6 Soils, agriculture, and the future of food

2. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings This lecture will help you understand: Soil science fundamentals Soil erosion and degradation Soil conservation policies Pest management and pollination Genetically modified food and preserving crop diversity Feedlot agriculture and Aquaculture Organic agriculture

3. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Central Case: No-Till Agriculture in Brazil Southern Brazil’s farmers were suffering falling yields, erosion, and pollution from agrichemicals. They turned to no-till farming, which bypasses plowing. Erosion was reduced, soils were enhanced, and yields rose greatly. No-till methods are spreading worldwide.

4. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Agriculture today We have converted 38% of Earth’s surface for agriculture, the practice of cultivating soil, producing crops, and raising livestock for human use and consumption. Croplands (for growing plant crops) and rangelands (for grazing animal livestock) depend on healthy soil.

5. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil as a system Parent material, such as bedrock, is weathered to begin process of soil formation. Parent material = the base geological material in a location Bedrock = the continuous mass of solid rock that makes up Earth’s crust Weathering = processes that break down rocks

6. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings World soil conditions Soils are becoming degraded in many regions. Figure 8.1a

7. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil degradation by continent Europe’s land is most degraded because of its long history of intensive agriculture. But Asia’s and Africa’s soils are fast becoming degraded. Figure 8.1b

8. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Causes of soil degradation Most soil degradation is caused by: livestock overgrazing deforestation cropland agriculture. Figure 8.2

9. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Components of soil Soil is a complex mixture of organic and inorganic components and living organisms.

10. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Humus Dark, crumbly mass of undifferentiated material made up of complex organic compounds Soils with high humus content hold moisture better and are more productive for plant life.

11. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil profile Consists of layers called horizons. Simplest: A = topsoil B = subsoil C = parent material But most have O, A, E, B, C, and R Figure 8.8

12. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil profile O Horizon: Organic or litter layer A Horizon: Topsoil. Mostly inorganic minerals with some organic material and humus mixed in. Crucial for plant growth E Horizon: Eluviation horizon; loss of minerals by leaching, a process whereby solid materials are dissolved and transported away B Horizon: Subsoil. Zone of accumulation or deposition of leached minerals and organic acids from above C Horizon: Slightly altered parent material R Horizon: Bedrock

13. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil characterization Figure 8.9 Soil can be characterized by color and several other traits: texture structure pH Best for plant growth is loam, an even mix of these three types.

14. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Erosion and deposition Erosion = removal of material from one place and its transport elsewhere by wind or water Deposition = arrival of eroded material at a new location These processes are natural, and can build up fertile soil. But where artificially sped up, they are a big problem for farming.

15. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Erosion Commonly caused by: Overcultivating, too much plowing, poor planning Overgrazing rangeland with livestock Deforestation, especially on slopes

16. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Types of soil erosion Figure 8.11 Splash erosion Rill erosion Gully erosion Sheet erosion

17. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Erosion: A global problem Over 19 billion ha (47 billion acres) suffer from erosion or other soil degradation. Figure 8.12

18. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Desertification A loss of more than 10% productivity due to: Erosion Soil compaction Forest removal Overgrazing Drought Salinization Climate change Depletion of water resources etc. When severe, there is expansion of desert areas, or creation of new ones, e.g., the Middle East, formerly, “Fertile Crescent”.

19. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Dust Bowl Drought and degraded farmland produced the 1930s Dust Bowl. Storms brought dust from the U.S. Great Plains all the way to New York and Washington, and wrecked many lives. Figure 8.14

20. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Soil conservation As a result of the Dust Bowl, the U.S. Soil Conservation Act of 1935 and the Soil Conservation Service (SCS) were created. SCS: Local agents in conservation districts worked with farmers to disseminate scientific knowledge and help them conserve their soil.

21. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Preventing soil degradation Several farming strategies to prevent soil degradation: Crop rotation Contour farming Intercropping Terracing Shelterbelts Conservation tillage

22. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Crop rotation Alternating the crop planted (e.g., between corn and soybeans) can restore nutrients to soil and fight pests and disease. Figure 8.16a

23. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Contour farming Planting along contour lines of slopes helps reduce erosion on hillsides. Figure 8.16b

24. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Intercropping Mixing crops such as in strip cropping can provide nutrients and reduce erosion. Figure 8.16c

25. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Terracing Cutting stairsteps or terraces is the only way to farm extremely steep hillsides without causing massive erosion. It is labor-intensive to create, but has been a mainstay for centuries in the Himalayas and the Andes. Figure 8.16d

26. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Shelterbelts Rows of fast-growing trees around crop plantings provide windbreaks, reducing erosion by wind. Figure 8.16e

27. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conservation tillage No-till and reduced-tillage farming leaves old crop residue on the ground instead of plowing it into soil. This covers the soil, keeping it in place. Here, corn grows up out of a “cover crop.” Figure 8.16f

28. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conservation tillage Conservation tillage is not a panacea for all crops everywhere. It often requires more chemical herbicides (because weeds are not plowed under). It often requires more fertilizer (because other plants compete with crops for nutrients). But legume cover crops can keep weeds at bay while nourishing soil, and green manures can be used as organic fertilizers.

29. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Irrigation The artificial provision of water to support agriculture 70% of all freshwater used by humans is used for irrigation. Irrigated land globally covers more area than all of Mexico and Central America combined. Irrigation has boosted productivity in many places … but too much can cause problems.

30. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Waterlogging and salinization Overirrigation can raise the water table high enough to suffocate plant roots with waterlogging. Salinization (buildup of salts in surface soil layers) is a more widespread problem. Evaporation in arid areas draws water up through the soil, bringing salts with it. Irrigation causes repeated evaporation, bringing more salts up.

31. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Improved irrigation In conventional irrigation, only 40% of the water reaches plants. Efficient drip irrigation targeted to plants conserves water, saves money, and reduces problems like salinization. Figure 8.17

32. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Fertilizers Supply nutrients to crops Inorganic fertilizers = mined or synthetically manufactured mineral supplements Organic fertilizers = animal manure, crop residues, compost, etc. Figure 8.18

33. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Global fertilizer usages Fertilizer use has risen dramatically in the past 50 years. Figure 8.19b

34. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Overgrazing When livestock eat too much plant cover on rangelands, impeding plant regrowth The contrast between ungrazed and overgrazed land on either side of a fenceline can be striking. Figure 8.22

35. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Overgrazing Overgrazing can set in motion a series of positive feedback loops. Figure 8.21

36. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Recent soil conservation laws The U.S. has continued to pass soil conservation legislation in recent years: Food Security Act of 1985 Conservation Reserve Program, 1985 Freedom to Farm Act, 1996 Low-Input Sustainable Agriculture Program, 1998 Internationally, there is the UN’s “FAR” program in Asia.

37. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Global food production World agricultural production has risen faster than human population. Figure 9.1

38. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Global food security However, the world still has 800 million hungry people, largely due to inadequate distribution. And considering soil degradation, can we count on food production continuing to rise? Global food security is a goal of scientists and policymakers worldwide.

39. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Nutrition Undernourishment = too few calories (especially developing world) Overnutrition = too many calories (especially developed world) Malnutrition = lack of nutritional requirements (causes numerous diseases, esp. in developing world) Figure 9.2

40. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The green revolution An intensification of industrialization of agriculture, which has produced large yield increases since 1950 Increased yield per unit of land farmed Begun in U.S. and other developed nations; exported to developing nations like India and those in Africa are more productive for plant life.

41. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Transgenic contamination? UC Berkeley researchers Ignacio Chapela (L) and David Quist (R) ignited controversy by claiming contamination of Mexican maize. They later admitted some flaws in their methods, but debate continued, revealing the personal and political pressures of high- stakes scientific research. From The Science behind the Stories

42. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Monocultures Intensified agriculture meant monocultures, vast spreads of a single crop. This is economically efficient, but increases risk of catastrophic failure (“all eggs in one basket”). Figure 9.4a Wheat monoculture in Washington

43. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Crop diversity Monocultures also have reduced crop diversity. 90% of all human food now comes from only 15 crop species and 8 livestock species.

44. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The green revolution Techniques to increase crop output per unit area of cultivated land (since world was running out of arable land) Technology transfer to developed world in 1940s-80s: Norman Borlaug began in Mexico, then India. Special crop breeds (drought-tolerant, salt-tolerant, etc.) are a key component. It enabled food production to keep pace with population.

45. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Green revolution: Environmental impacts Intensification of agriculture causes environmental harm: Pollution from synthetic fertilizers Pollution from synthetic pesticides Water depleted for irrigation Fossil fuels used for heavy equipment However, without the green revolution, much more land would have been converted for agriculture, destroying forests, wetlands, and other ecosystems.

46. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Feeding the world In 1983, the amount of grain produced per capita leveled off and began to decline. Figure 8.3

47. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pest management Terms pest and weed have no scientific or objective definitions. Any organism that does something we humans don’t like gets called a pest or a weed. The organisms are simply trying to survive and reproduce… and a monoculture is an irresistible smorgasbord of food for them.

48. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Chemical pesticides Synthetic poisons that target organisms judged to be pests

49. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pesticide use Pesticide use is still rising sharply across the world, although growth has slowed in the U.S. 1 billion kg (2 billion lbs.) of pesticides are applied each year in the U.S. Figure 9.5

50. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pests evolve resistance to pesticides Pesticides gradually become less effective, because pests evolve resistance to them. Those few pests that survive pesticide applications because they happen to be genetically immune will be the ones that reproduce and pass on their genes to the next generation. This is evolution by natural selection, and it threatens our very food supply.

51. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pests evolve resistance to pesticides 1. Pests attack crop 2. Pesticide applied Figure 9.6

52. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pests evolve resistance to pesticides 3.All pests except a few with innate resistance are killed 4.Survivors breed and produce pesticide-resistant population Figure 9.6

53. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pests evolve resistance to pesticides 5.Pesticide applied again 6.Has little effect. More-toxic chemicals must be developed. Figure 9.6

54. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Biological control Synthetic chemicals can pollute and be health hazards. Biological control (biocontrol) avoids this. Biocontol entails battling pests and weeds with other organisms that are natural enemies of those pests and weeds. (“The enemy of my enemy is my friend.”)

55. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Biological control Biocontrol has had success stories. Bacillus thuringiensis (Bt) = soil bacterium that kills many insects. In many cases, seemingly safe and effective. Figure 9.7 Cactus moth, Cactoblastis cactorum (above), was used to wipe out invasive prickly pear cactus in Australia.

56. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings But biocontrol is risky Most biocontrol agents are introduced from elsewhere. Some may turn invasive and become pests themselves! Cactus moths brought to the Caribbean jumped to Florida, are eating native cacti, and spreading. Wasps and flies brought to Hawaii to control crop pests are parasitizing native caterpillars in wilderness areas.

57. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Integrated pest management (IPM) Combines biocontrol, chemical, and other methods May involve: Biocontrol Pesticides Close population monitoring Habitat modification Crop rotation Transgenic crops Alternative tillage Mechanical pest removal

58. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Pollination Process of plant reproduction: male pollen meets female sex cells In many plants, animals transfer pollen to pollinate female plants, in mutualistic interaction to obtain nectar or pollen. Figure 9.9 Honeybee pollinating apple blossom

59. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Genetic modification of food Manipulating and engineering genetic material in the lab may represent the best hope for increasing agricultural production further without destroying more natural lands. But many people remain uneasy about genetically engineering crop plants and other organisms.

60. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Genetic engineering uses recombinant DNA 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 DNA of multiple organisms (e.g., adding disease-resistance genes from one plant to the genes of another)

61. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Transgenes and biotechnology Genes moved between organisms are transgenes, and the organisms are transgenic. These efforts are one type of biotechnology, the material application of biological science to create products derived from organisms.

62. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Genetic engineering vs. traditional breeding They are similar: We have been altering crop genes (by artificial selection) for thousands of years. There is no fundamental difference: both approaches modify organisms genetically. They are different: GE can mix genes of very different species. GE is in vitro lab work, not with whole organisms. GE uses novel gene combinations that didn’t come together on their own.

63. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Some GM foods Figure 9.12 Golden rice: Enriched with vitamin A. But too much hype? Bt crops: Widely used on U.S. crops. But ecological concerns? Ice-minus strawberries: Frost- resistant bacteria sprayed on. Images alarmed public. FlavrSavr tomato: Better taste? But pulled from market.

64. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Some GM foods Figure 9.12 Bt sunflowers: Insect resistant. But could hybridize with wild relatives to create “superweeds”? Terminator seeds: Plants kill their own seeds. Farmers forced to buy seeds each year. Roundup-Ready crops: Resistant to Monsanto’s herbicide. But encourages more herbicide use? StarLink corn: Bt corn variety. Genes spread to non-GM corn; pulled from market.

65. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings 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. Two-thirds of U.S. soybeans, corn, and cotton are now genetically modified strains.

66. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Prevalence of GM foods Nearly 6 million farmers in 16 nations plant GM crops. But most are grown by 4 nations. The U.S. grows 66% of the world’s GM crops. number of plantings have grown >10%/year Figure 9.13

67. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Scientific concerns about GM organisms 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 crop races and ruin their integrity?

68. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Scientific concerns about GM organisms These questions are not fully answered yet. In the meantime… Should we not worry, because so many U.S. crops are already GM and little drastic harm is apparent? Or should we adopt the precautionary principle, the idea that one should take no new action until its ramifications are understood?

69. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Socioeconomic and political concerns about GM products Should scientists and corporations be “tinkering with” our food supply? Are biotech corporations testing their products adequately, and is outside oversight adequate? Should large multinational corporations exercise power over global agriculture and small farmers?

70. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Europe vs. America Europe: has followed precautionary principle in approach to GM foods. Governments have listened to popular opposition among their citizens. U.S.: GM foods were introduced and accepted with relatively little public debate. Relations over agricultural trade have been uneasy, and it remains to be seen whether Europe will accept more GM foods from the U.S.

71. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Viewpoints: Genetically modified foods Indra Vasil Ignacio Chapela “We should expect fundamental alterations in ecosystems with the release of transgenic crops… We are experiencing a global experiment without controls.” “Biotech crops are already helping to conserve valuable natural resources, reduce the use of harmful agro- chemicals, produce more nutritious foods, and promote economic development.” From Viewpoints

72. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Preserving crop diversity Native cultivars of crops are important to preserve, in case we need their genes to overcome future pests or pathogens. Diversity of cultivars has been rapidly disappearing from all crops throughout the world.

73. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings 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. Figure 9.14

74. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Animal agriculture: Livestock and poultry Consumption of meat has risen faster than population over the past several decades. Figure 9.15

75. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Feedlot agriculture Increased meat consumption has led to animals being raised in feedlots (factory farms), huge pens that deliver energy- rich food to animals housed at extremely high densities. Figure 9.16

76. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings 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 However, if all these animals were grazing on rangeland, how much more natural land would be converted for agriculture?

77. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Food choices = energy choices Energy is lost at each trophic level. When we eat meat from a cow fed on grain, most of the grain’s energy has already been spent on the cow’s metabolism. Eating meat is therefore very energy inefficient.

78. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Grain feed input for animal output Some animal food products can be produced with less input of grain feed than others. Figure 9.17

79. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Land and water input for animal output Some animal food products can be produced with less input of land and water than others. Figure 9.18

80. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Aquaculture The raising of aquatic organisms for food in controlled environments Provides 1/3 of world’s fish for consumption 220 species being farmed The fastest growing type of food production

81. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Aquaculture Fish make up half of aquacultural production. Molluscs and plants each make up nearly 1/4. Global aquaculture has been doubling about every 7 years. Figure 9.19

82. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Benefits of aquaculture Provides reliable protein source for people, increases food security Can be small-scale, local, and sustainable Reduces fishing pressure on wild stocks, and eliminates bycatch Uses fewer fossil fuels than fishing Can be very energy efficient

83. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Environmental impacts of aquaculture Density of animals leads to disease, antibiotic use, risks to food security. It can generate large amounts of waste. Often animals are fed grain, which is not energy efficient. Sometimes animals are fed fish meal from wild-caught fish. Farmed animals may escape into the wild and interbreed with, compete with, or spread disease to wild animals.

84. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Environmental impacts of aquaculture Transgenic salmon (top) can compete with or spread disease to wild salmon (bottom) when they escape from fish farms. Figure 9.20

85. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Sustainable agriculture Agriculture that can 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. Instead, biocontrol, composting, etc.

86. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Organic farming Small percent of market, but is growing fast 1% of U.S. market, but growing 20%/yr 3–5% of European market, but growing 30%/yr Organic produce: Advantages for consumers: healthier; environmentally better Disadvantages for consumers: less uniform and appealing- looking; more expensive

87. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conclusions: Challenges Chemical pesticides pollute, and kill pollinators, and pests evolve resistance. GM crops show promise for social and environmental benefits, but questions linger about their impacts. Much of the world’s crop diversity has vanished. Feedlot agriculture and aquaculture pose benefits and harm for the environment and human health.

88. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conclusions: Challenges Organic farming remains a small portion of agriculture. Human population continues to grow, requiring more food production. Soil erosion is a problem worldwide. Salinization, waterlogging, and other soil degradation problems are leading to desertification. Grazing and logging, as well as cropland agriculture, contribute to soil degradation.

89. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conclusions: Solutions Biocontrol and IPM offer alternatives to pesticides. Further research and experience with GM crops may eventually resolve questions about impacts, and allow us to maximize benefits while minimizing harm. More funding for seed banks can rebuild crop diversity. Ways are being developed to make feedlot agriculture and aquaculture safer and cleaner.

90. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Conclusions: Solutions Organic farming is popular and growing fast. Green revolution advances have kept up with food demand so far. Improved distribution and slowed population growth would help further. Farming strategies like no-till farming, contour farming, terracing, etc., help control erosion. Government laws, and government extension agents working with farmers, have helped improve farming practices and control soil degradation. Better grazing and logging practices exist that have far less impact on soils.

91. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Integrated pest management may involve all of the following EXCEPT… ? a.Close population monitoring b. Biocontrol c.Exclusive reliance on pesticides d.Habitat modification e.Transgenic crops

92. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review What do seed banks do? a.Lend money to farmers to buy seeds b.Pay farmers to store seeds c.Buy seeds from farmers d.Store seeds to maintain genetic diversity e.None of the above

93. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which is NOT a benefit of aquaculture? a.Provides a reliable protein source b. Reduces pressure on natural fisheries c.Produces no waste d.Uses fewer fossil fuels than commercial fishing e.All of the above are benefits

94. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Weighing the Issues Can we call the green revolution a success? a. A huge success; it has saved millions from starvation because it increased food production to keep pace with population growth. b.Not a success; its environmental impacts have outweighed its claimed benefits. c.A success; its environmental impacts are balanced by the fact that it saved huge areas from deforestation.

95. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data With 500 kg of water, you could produce … ? a.2 kg of protein from milk b. Protein from 50 chickens c.750 kg of protein from beef d.15 eggs Figure 9.18b

96. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Viewpoints Should we encourage the continued development of GM foods? a. Yes; they will bring many health, social, and environmental benefits. b.No, we should adopt the precautionary principle, and not introduce novel things until we know they are safe. c.Yes, but we should proceed cautiously, and consider each new crop separately.

97. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which statement is NOT correct? a.Soil consists of disintegrated rock, organic matter, nutrients, and microorganisms. b. Healthy soil is vital for agriculture. c. Soil is somewhat renewable. d.Soil is lifeless dirt. e.Much of the world’s soil has been degraded.

98. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review The A horizon in a soil profile… ? a.Is often called the “zone of accumulation.” b.Is often called “topsoil.” c.Contains mostly organic matter. d.Is the lowest horizon, deepest underground.

99. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Erosion occurs through… ? a.Deforestation. b.Excessive plowing. c.Overgrazing rangelands. d.Two of the above. e.All of the above.

100. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Drip irrigation differs from conventional irrigation in that … ? a.It is much less efficient. b.It can cause salinization. c.Water is precisely targeted to plants. d.About 40% is wasted.

101. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Weighing the Issues You are farming an extremely steep slope that is sunny and very windy. What strategies would you consider using? a.Crop rotation b.Contour farming c.Intercropping d.Terracing e.Shelterbelts f.No-till farming

102. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Grain produced per person has… ? a.Risen steadily b.Fallen sharply c.Increased since 1983 Decreased since 1983 Figure 8.3

103. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Industrialized agriculture Modern intensive agriculture on a large scale: Crop monocultures Synthetic chemical herbicides, pesticides Extensive mechanization Fossil fuel use