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Chapt07 Lecture Presentation Transcript

  • 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 7 Lecture Outline
  • 2. Learning Outcomes After studying this chapter, you should be able to answer the following questions:
    • • How have global food production and population changed?
    • • How many people are chronically hungry, and why does hunger persist in a world of surpluses?
    • • What are some health risks of undernourishment, poor diet, and overeating?
    • • What are our primary food crops?
    • • Describe five components of soil.
    • • What was the green revolution?
    • • What are GMOs, and what traits are most commonly introduced with GMOs?
    • • Describe some environmental costs of farming, and ways we can minimize these costs.
    7-
  • 3. We can’t solve problems by using the same kind of thinking we used when we created them. –Albert Einstein 7-
  • 4. 7.1 Global Trends in Food and Nutrition
    • Food production has been transformed from small-scale, diversified, family operations to expansive farms of thousands of hectares, growing one or two genetically modified crops, with abundant inputs of fuel and fertilizer, for a competitive global market.
    7-
  • 5. Hunger around the world 7-
  • 6. Food security is unevenly distributed
    • Four decades ago, hunger was one of the world’s most prominent, persistent problems.
    • In 1960, nearly 60 percent of people in developing countries were chronically undernourished, and the world’s population was increasing by more than 2 percent every year.
    • Today, some conditions have changed dramatically; others have changed very little.
    • The world’s population has risen from 3 billion to over 6.5 billion, but food production has increased even faster.
    7-
  • 7. Food security is unevenly distributed…
    • Food security is the ability to obtain sufficient, healthy food on a day-to-day basis, is a combined problem of economic, environmental, and social conditions.
    • In wealthy countries such as the United States, millions lack a sufficient, healthy diet.
    • In the poorest countries, entire national economies can suffer from a severe drought, flood, or insect outbreak.
    7-
  • 8. Famines usually have political and social roots
    • Globally, widespread hunger arises when political instability, war, and conflict displace populations, removing villagers from their farms or making farming too dangerous to carry on.
    • Famines are large-scale food shortages, with widespread starvation, social disruption, and economic chaos.
    7-
  • 9. 7-
  • 10. 7.2 Eating Right to Stay Healthy
    • A good diet is essential to keep you healthy.
    • You need the right nutrients, as well as enough calories for a productive and energetic lifestyle.
    7-
  • 11. A healthy diet includes the right nutrients
    • Malnourishment is a general term for nutritional imbalances caused by a lack of specific nutrients.
    7-
  • 12. The Harvard food pyramid 7-
  • 13. Overeating is a growing world problem
    • Increasing world food supplies and low prices cause increasing overweight and obese populations.
    • In the U.S., and increasingly in Europe, China, and developing countries, highly processed foods rich in sugars and fats have become a large part of our diet.
    • Some 64 percent of adult Americans are overweight, up from 40 percent only a decade ago. About one-third of us are seriously overweight, or obese (generally considered to mean more than 20 percent over the ideal weight for a person’s height and sex.
    7-
  • 14. 7.3 The Foods We Eat
    • Of the thousands of edible plants and animals in the world, only a few provide almost all our food.
    7-
  • 15. A boom in meat production brings costs and benefits
    • Because of dramatic increases in corn and soy production, meat consumption has grown in both developed and developing countries.
    • Meat is a concentrated, high-value source of protein, iron, fats, and other nutrients that give us the energy to lead productive lives.
    7-
  • 16. Meat is a good indicator of wealth 7-
  • 17. Confined animal feeding operation (CAFO) 7-
  • 18. Seafood is both wild and farmed
    • Overharvesting and habitat destruction threaten most of the world’s wild fisheries.
    • The problem is too many boats using efficient but destructive technology to exploit a dwindling resource base.
    • Aquaculture is providing an increasing share of the world’s seafood.
    7-
  • 19. Fish pins
    • Net pens anchored in nearshore areas allow spread of diseases, escape of exotic species, and release of feces, uneaten food, antibiotics, and other pollutants into surrounding ecosystems.
    7-
  • 20. Increased production comes with increased risks
    • There are many environmental worries about this efficient production.
      • Land conversion from pasture to soy and corn fields raises the rate of soil erosion.
      • Constant use of antibiotics raises the very real risk of antibiotic-resistant diseases.
    7-
  • 21. 7.4 Soil Is a Living Resource
    • Soil is a marvelous substance, a living resource of astonishing complexity and frailty.
    • It is a complex mixture of:
      • mineral grains weathered from rocks,
      • partially decomposed organic molecules, and
      • a host of living organisms.
    • Soil can be considered a living ecosystem by itself.
    7-
  • 22. What is soil?
    • Soil is a complex mixture of six components:
      • sand and gravel-mineral particles from bedrock, either in place or moved from elsewhere, as in wind-blown sand.
      • silts and clays -extremely small mineral particles; many clays are sticky and hold water because of their flat surfaces and ionic charges; others give red color to soil.
      • dead organic material-decaying plant matter stores nutrients and gives soils a black or brown color.
      • soil fauna and flora -living organisms, including soil bacteria, worms, fungi, roots of plants, and insects, recycle organic compounds and nutrients.
      • water -moisture from rainfall or groundwater, essential for soil fauna and plants.
      • air -tiny pockets of air help soil bacteria and other organisms survive.
    7-
  • 23. 7-
  • 24. Soil Horizons 7-
  • 25. 7.5 Ways We Use and Abuse Soil
    • Agriculture both causes and suffers from environmental degradation.
    • The causes of this extreme degradation vary:
      • In Ethiopia, it is water erosion.
      • In Somalia, it is wind; and in Uzbekistan, salt and toxic chemicals are responsible.
      • In Sweden and Finland, fallout from the Chernobyl nuclear reaction explosion has contaminated large amounts of grazing land and farmland.
    7-
  • 26. Causes of Soil Erosion and Degradation 7-
  • 27. Farming accelerates erosion
    • Erosion is an important natural process, resulting in the redistribution of the products of geologic weathering, and it is part of both soil formation and soil loss.
    • Where erosion has worn down mountains and spread soil over the plains or deposited rich alluvial silt in river bottoms, we farm it.
    7-
  • 28. Wind and water move soil
    • Sheet erosion: water flowing across a gently sloping, bare field removing a thin, uniform layer of soil.
    • Rill erosion: when little rivulets of running water gather together and cut small channels in the soil.
    • Gully erosion: if rills enlarge to form bigger channels or ravines that are too large to be removed by normal tillage operations.
    • Desertification: conversion of productive land to desert.
    7-
  • 29. Wind and water are the main agents that move soil around. 7-
  • 30. Wind can equal or exceed water in erosive force
    • In extreme conditions, windblown dunes encroach on useful land and cover roads and buildings.
    • Over the past 30 years, China has lost 93,000 km2 (about the size of Indiana) to desertification.
    • Advancing dunes from the Gobi desert are now only 160 km (100 mi) from Beijing.
    7-
  • 31. 7.6 Other Agricultural Resources
    • Irrigation is necessary for high yields
      • Agriculture accounts for the largest single share of global water use.
      • Salinization: mineral salts accumulate in the soil due to evaporating water from irrigation.
    • Fertilizer boosts production
      • Much of the doubling in worldwide crop production since 1950 has come from increased inorganic fertilizer use.
    • Modern agriculture runs on oil
    • Pest control saves crops
    7-
  • 32. 7.7 How We Have Managed to Feed Billions
    • In the developed countries, 95 percent of agricultural growth in the twentieth century came from improved crop varieties ( the green revolution) or increased fertilization, irrigation, and pesticide use, rather than from bringing new land into production.
    7-
  • 33. The green revolution has increased yields
    • Most of this gain was accomplished by use of synthetic fertilizers along with conventional plant breeding: geneticists laboriously hand-pollinating plants and looking for desired characteristics in the progeny.
    • Starting about 50 years ago, agricultural research stations began to breed tropical wheat and rice varieties that would provide food for growing populations in developing countries.
    7-
  • 34. Genetic engineering could have benefits and costs
    • Genetic engineering: splicing a gene from one organism into the chromosome of another.
    • Genetically modified organisms (GMOs ): organisms with entirely new genes, and even new organisms, often called “transgenic” organisms.
    7-
  • 35. Is genetic engineering safe?
    • The greatest danger is the ecological effects if these organisms spread into the native populations.
    • There are social and economic implications of GMOs. Will they help feed the world, or will they lead to a greater consolidation of corporate power and economic disparity?
    • Are GMO’s required if we hope to reduce malnutrition and feed eight billion people in 50 years.
    7-
  • 36. 7.8 Alternatives in Food and Farming
    • Soil conservation is essential
      • With careful husbandry, soil is a renewable resource that can be replenished and renewed indefinitely.
      • Water runoff can be reduced by grass strips in waterways and by contour plowing, plowing across the hill rather than up and down.
      • Terracing is shaping the land to create level shelves of earth to hold water and soil.
    7-
  • 37. Soil conservation is essential 7-
  • 38. 7.9 Consumer Choices Can Reshape Farming
    • You can be a locavore
      • Locavore: a person who consumes locally produced food.
    • You can eat low on the food chain
      • Since there is less energy involved in producing food from plants, you can reduce your impact by eating more grains, vegetables, and dairy and a little less meat.
    • You can eat organic, low-input foods
      • If you buy organic food, you are supporting farmers who use no pesticides or artificial fertilizers.
    7-
  • 39. Practice Quiz
    • 1. What is Brazil’s Cerrado, and how is agriculture affecting it?
    • 2. Explain how soybeans grown in Brazil are improving diets in China.
    • 3. What does it mean to be chronically undernourished? How many people in the world currently suffer from this condition?
    • 4. Why do nutritionists worry about food security? Who is most likely to suffer from food insecurity?
    • 5. Describe the conditions that constitute a famine. Why does Amartya Sen say that famines are caused more by politics and
    • economics than by natural disasters?
    • 6. Define malnutrition and obesity. How many Americans are now considered obese?
    • 7. What three crops provide most human caloric intake?
    7-