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Chapter 7LectureOutline

Learning OutcomesAfter 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.

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We can’t solve problems by using the same kind of thinking we used when we created them.

–Albert Einstein

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7.1 Global Trends in Foodand 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.

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Hunger around the world

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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.

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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.

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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.

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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.

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A healthy diet includes the right nutrients

• Malnourishment is a general term for nutritional imbalances caused by a lack of specific nutrients.

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The Harvard food pyramid

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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.

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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.

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A boom in meat productionbrings 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.

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Meat is a good indicator of wealth

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Confined animal feeding operation (CAFO)

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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.

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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.

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Increased production comeswith 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.

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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.

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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.

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Soil

Hor

izon

s

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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.

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Causes of Soil Erosion and Degradation

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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.

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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.

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Wind and water are the main agents that move soil around.

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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.

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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

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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.

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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.

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Genetic engineering couldhave 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.

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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.

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7.8 Alternatives in Foodand 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.

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Soil conservation is essential

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7.9 Consumer ChoicesCan 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.

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Practice Quiz1. 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 andeconomics 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?

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