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Lecture Outlines

ENVIRONMENT the science behind the stories

Chapter 10

Making Agriculture Sustainable

Lecture objectives  Explain the challenge of feeding the human

population.  Identify the goals, methods, and consequences of

the Green Revolution.  Discuss how we raise animals for food, and assess

the impacts that result.  Describe reasons and approaches for preserving

crop diversity.  Discuss threats to pollinators and identify potential

solutions.  Explore strategies for pest and weed management.

Lecture objectives  Describe the science behind genetic engineering.  Compare the benefits and costs of genetically

modified foods, and assess the public debate over them.

 Analyze the nature, growth, and potential of organic agriculture.

 Contrast conventional industrial, organic, and biotech approaches to agriculture.

 Summarize potential pathways to sustainable agriculture.

Can Organic Farming and GMOs Coexist?  Steve Marsh grows many

organic crops on his farm, including wheat, rye, and oats. His neighbor, Michael Baxter, grows Roundup Ready Canola.

 This canola is a genetically modified crop engineered by Monsanto Company.  The crop can be sprayed with Roundup herbicide

without it being harmed.

 When Baxter harvested his canola, some of the seeds, stalks, and leaves blew into Marsh’s fields.  Inspectors decertified the crops as organic due to the

presence of genetically-modified material.  Marsh sued Baxter for his loss, a case that went to

the Western Australia’s Supreme Court.  Marsh lost the case, with the court declaring that

Baxter had done nothing illegal.  A 2010 law passed in Australia allowed Baxter to

grow the genetically modified crops, but national laws also set a zero-tolerance threshold GM material in organic crops.  Organic farmers face a dilemma: how to preserve the

The Race to Feed the World  The industrialization of agriculture has boosted

worldwide production of food and fiber immensely, but has also brought increased pollution and resource depletion.  Organic farming decreases efficiency, but also has far

fewer environmental impacts.

We face undernutrition, overnutrition, and malnutrition  Despite improved food production, 800 million

people suffer from undernutrition, receiving fewer calories than the minimum dietary requirement.

 Most people who are undernourished live in developing countries, although 49 million people are classified as “food insecure”.  Food security is the guarantee of an adequate, safe,

nutritious, and reliable food supply.

 The number of people suffering from food insecurity has decreased since the 1960s.

 Overnutrition, receiving too many calories per day, has grown in developing countries due to the abundance of cheap junk food and sedentary lifestyles.  Excess weight leads to heart disease, diabetes,

stroke, some forms of cancer, and other health issues.

 Malnutrition is a shortage of specific nutrients, such as lipids, proteins, vitamins, or minerals.  People with protein-

deficient diets can develop kwashiorkor, which causes bloating of the abdomen, deterioration of hair, mental disability, and other issues.  Protein deficiency and a loss of calories can lead to

marasmus.  A deficiency of iron leads to anemia.

The Green Revolution boosted agricultural production  The Green Revolution

introduced new technologies, crop varieties, and farming practices to the developed world.  This began in the 1940s

when Norman Borlaug introduced Mexico’s farmers to a disease-resistant, high-yield strain of wheat.  Mexico was able to triple its wheat production, and

the same practices were applied to India and Pakistan.

Industrialized agriculture has brought mixed consequences  Along with new crop varieties, developing countries

imported the use of synthetic fertilizers, pesticides, intensive irrigation, and fossil fuel-powered machinery.  This allowed India to transform from a country with

high rates of starvation to a net exporter of grain.

 The Green Revolution helped increase per-person food production by 48%, while only increasing land use by 11%, helping to preserve biodiversity.  Intensive use of fertilizers and pesticides has

worsened pollution, erosion, and water and air quality.

 In conventional industrial agriculture, crops are planted in monocultures (vast expanses with single crop types).  This increases efficiency but also reduces

biodiversity.  Monocultures are also more susceptible to disease

and insect pests.

How can we achieve sustainable agriculture?  Sustainable agriculture consists of farming and

grazing that maintain the healthy soil, clean water, pollinators, genetic diversity, and other resources needed over the long term.

 Reduction of fossil fuels and pollution are seen as key goals in this movement. Possible solutions include:  Increase in organic farming  Improved technologies  Greater use of genetically-modified crops

Review Questions 1. Individuals from a poor rural village are

experiencing enlarged thyroid glands as a result of insufficient levels of the nutrient iodine in their diets. This would be classified as a. undernutrition. b. overnutrition. c. malnutrition. d. hypernutrition.

Review Questions 1. Individuals from a poor rural village are

Review Questions 2. Which of these changes occurred in developing

countries during the Green Revolution? a. Decreased rates of irrigation b. Lower crop production per land area c. Application of chemical pesticides and fertilizers d. Reduction in fossil fuel consumption

Review Questions 2. Which of these changes occurred in developing

Raising Animals for Food  As global wealth and commerce have increased, so

has the production and consumption of meat, milk, eggs, and other animal products.  Meat production has grown more than fivefold since

1950, and per capita meat consumption has doubled.

Our food choices have environmental consequences  Every time that one organism consumes another,

only about 10% of the energy moves to the next trophic level.  Feeding grain to a cow and eating beef from the cow

loses most of the grain’s energy to the cow’s metabolism.

 Eating lower on the food chain (a more vegetarian diet) is more energy-efficient and reduces our ecological footprint.

 Some animals convert grain feed into milk, meat, or eggs more efficiently than others.

 Based on these difference in energy conversion efficiencies, a footprint of land area, water weight, and CO2 equivalents has been calculated for producing 1 kg of edible protein for each animal.  Animal agriculture accounts for 14.5% of our green

house gas emissions—more than driving.

Feedlots have benefits and costs  Feedlots are huge pens

designed to provide high-energy feed to animals living in high densities.  Also known as factory

farms or confined animal feeding operations (CAFOs).

 Feedlots have the benefit of being more economically efficient and reducing grazing impacts by the animals.

 Feedlots can also produce more intensive pollution due to the release of highly concentrated waste.  Rich in nitrogen and phosphorous, so it contributes to

eutrophication.  Contains bacterial and viral pathogens.

 Hormones, antibiotics, and other drugs administered to animals may be excreted in waste, as well.

We use aquaculture to raise seafood  Due to plummeting wild fish populations and

increasing demand for seafood, aquaculture, the cultivation of aquatic organisms in controlled environments, may be the answer.

 A wide variety of aquatic organisms are now being raised through aquaculture, with production growing 10-fold in the past 30 years.

Aquaculture brings benefits and costs  Aquaculture increases food supplies and protein

sources, increasing overall food security.  Also helps to reduce overfishing of wild fish and the

unintended catch of other organisms called bycatch.  At large scales, industrialized aquaculture may

necessitate antibiotic overuse, destroy coastal ecosystems and spread disease or invasive species if the farmed organisms escape into the surrounding ecosystem.

 The first genetically modified animal to become approved for human consumption is a salmon that can grow faster and reach larger sizes than wild individuals.

Review Questions 3. The most efficient and lowest-footprint source of

calories would be which food source? a. Eggs from a feedlot chicken b. Beef from a pastured cow c. Milk from a feedlot cow d. Grain, such as corn or wheat

Review Questions 3. The most efficient and lowest-footprint source of

calories would be which food source? a. Eggs from a feedlot chicken b. Beef from a pastured cow c. Milk from a feedlot cow d. Grain, such as corn or wheat

Preserving Crop Diversity and Pollinators  A modern industrial monoculture is risky, because a

single catastrophe could wipe out the entire crop.  About 90% of food consumed now comes from just

15 crop species and 8 livestock species.  Preserving locally adapted varieties of crops called

landraces provides genetic diversity that could someday be introduced into commercial crops to confer resistance to disease or pests.

 Hundreds of landraces have been bred in Mexico from wild maize.

 Thousands of diverse potato varieties survive in the Andes Mountains, where they were first cultivated.

Seedbanks are living museums  Seed banks are institutions that preserve seed

types to preserve this genetic diversity.  The “doomsday seed vault” in Arctic Norway is built

into a mountain in an area of permanently frozen ground and contains millions of seeds from all over the world.

Bee declines make pollinator conservation urgent  Honeybees and other insects provide an estimated

$15 billion per year in pollination services, but wild populations are declining steeply across North America.

 Sources of this population decline:  Direct mortality from insecticide application  Introduction of parasites and pathogens from human

travel and trade  Habitat and flower loss due to application of

herbicides on farms and lawns

 A mysterious disease called colony collapse disorder has destroyed up to a third of all honeybees each year.  Cause is believed to be a

combination of the factors in the previous slide.

 Preserving buffer strips of wildflowers surrounding farms and along highways can help preserve pollinators.

Controlling Pests and Weeds  A pest is any organism that damages crops or

livestock.  A weed is any plant that competes with crops.  Industrial monocultures limit the ability of natural

enemies to control pest populations, causing farmers to turn to chemical suppression.

We have developed thousands of chemical pesticides  Pesticides include synthetic chemicals that kill

insects (insecticides), plants (herbicides), and fungi (fungicides).  Nearly 400 million kg of ingredients from pesticides

are applied in the United States each year.

Pesticides boost food production but also have negative impacts  Exposure to pesticides can have health

consequences for people.  Farm workers have the highest levels of exposure.  Consumers ingest pesticide residues when

non-organic produce is eaten.  Pesticides also kill non-target organisms, including

predators and parasites of pests and pollinators.  Roundup, for example, has reduced milkweed

populations so much that Monarch butterfly populations have plummeted.

 A new class of chemical insecticide in use today are neonicotinoids.  These make the plant toxic to insects that feed on

them, but also harm bees that pollinate the plant and predator insects that feed on the pests.  Neonicotinoids also enter the soil and water supply,

killing other organisms that pose no threat to crops.

Pests evolve resistance to pesticides  Chemical pesticides tend to become less effective in

time as pests evolve resistance to them.  Most pests occur in huge numbers, so it is likely that

a few of them have genes that detoxify or metabolize a given pesticide.

 Individuals with the gene will survive and reproduce at greater rates, creating a new generation with a much higher rate of carrying the gene.  Eventually the pesticide becomes ineffective and

must be replaced by a new one. This is called the “pesticide treadmill”.

Biological control pits one organism against another  The most obvious alternative to

chemical pesticides is biological control, where natural predators or parasites are introduced to eliminate the pest.  In the 1920s, the cactus moth

was successfully introduced into Australia to control the invasive prickly pear cactus.

 A modern example of biological control is the use of the Bacillus thuringiensis (Bt) soil bacterium, which produces a protein that kills many caterpillars, and some fly and beetle larvae.  Bt spores can be sprayed directly on plants.  The gene responsible for producing the protein has

been genetically engineered into crop plants, allowing them to produce the poison.

Biocontrol agents themselves can become pests  When a pest is a non-native species, scientists may

consider introducing a non-native predator to combat it.  This is risky, because the full effects of introducing a

new species cannot be predicted.  The cactus moth employed in Australia to fight

prickly pear cactus was also used in Caribbean countries, but has spread into the United States and is now consuming native cacti.

Integrated pest management combines biochemical and chemical methods  Integrated pest

management (IPM) combines biocontrol, chemical pesticides, habitat alteration, crop rotation, transgenic crops, alternative tillage methods, and mechanical pest removal.  This has been highly effective in Indonesia, which

increased rice production while cutting pesticide subsidies and overall pesticide use.

Review Questions 4. Which of these methods would be considered

integrated pest management? a. Spraying a field with neonicotinoids to kill insects b. Spreading spores of a pest-killing bacterium like

Bacillus thuringiensis c. Moving from a monoculture to a polyculture d. All of these methods would be part of an IPM

strategy.

Review Questions 4. Which of these methods would be considered

integrated pest management? a. Spraying a field with neonicotinoids to kill insects b. Spreading spores of a pest-killing bacterium like

Bacillus thuringiensis c. Moving from a monoculture to a polyculture d. All of these methods would be part of an IPM

strategy.

Genetically Modified Food  Genetic engineering refers to any process where

scientists directly manipulate an organism’s genetic material (DNA).

 Genetically modified foods are those derived from genetically modified organisms (GMOs).

 Genetic engineering uses recombinant DNA, meaning it has been produced from multiple organisms.

 To create Roundup-Ready soybeans, scientists transferred a gene from the soil bacterium Agrobacterium tumefaciens that codes for an enzyme that is insensitive to the pesticide.  The gene’s expression is

regulated by three other genes—one from Agrobacterium, one from a petunia, and another from the California mosaic virus.

Genetic engineering is both like—and unlike— traditional breeding  In principle, the idea of genetically altering plants

and animals is similar to the process of artificial selection.  The technique is different—breeding uses the same

species, while genetic engineering crosses different species.  Genetic engineering also creates combinations of

genes in a more direct way that would not be possible with breeding.

Biotechnology is transforming the products around us  GM crops have been adopted and planted around

the world. Examples include:

 Estimates suggest that 70% of processed foods contain at least one ingredient from a GMO.  Most likely corn or soy.

 Five countries—the United States, Brazil, Argentina, India, and Canada—account for 90% of the production of GM crops.  Is this movement beneficial to farms and the

environment, or too risky?

What are the benefits of GM crops?  Most biotech crops so far have been engineered for

insect resistance and herbicide tolerance—primarily benefiting large-scale industrial farmers and not poor, rural ones.

 Proponents of GM crops argue they can:  Enhance food security and reducing poverty.  Alleviate pressure to clear forests and grasslands.  Conserve water by reducing the need for irrigation.  Improve nutrition with crops that contain key nutrients

(such as golden rice and vitamin A).  Reduction in pesticide application.

 A meta-analysis, an effort that gathers results from all scientific studies on a topic, was conducted regarding these claimed benefits. GM crops:  Increased yields by 22%.  Boosted farmers’ profits by 68%.  Reduced chemical pesticide use by 37%.

 While overall pesticide use declined, use of herbicides increased dramatically in areas where Roundup-Ready corn was planted.

 Herbicide use is also growing because many weeds are developing resistance to it, spurring farmers to apply even more.

What are the risks of GM crops?  Scientific research has not detected any significant

health hazards from ingesting genetically engineered crops.

 Ecologically, scientists are concerned that GMOs will interbreed with their wild relatives, transferring new genes into the wild population.  If Roundup-Ready genes enter the wild population, it

could produce herbicide-resistant “superweeds”.  Some feel we should adopt the precautionary

principle and not proceed until the effects of GM crops are fully understood.

Public debate over GMOs continues  A big part of the public debate is that every person

relies on food for survival, and genetic modification of rice, corn, soy, and wheat essentially forces people to consume biotech products.

 Another concern is that a few large companies such as Monsanto, Bayer, DOW, DuPont, and BASF control GM technology.

 In 2013, a budget bill passed by the U.S. Senate stripped courts of the ability to revoke USDA approval of any GM crop found to be unsafe.  The “Monsanto Protection Act” inspired a groundswell

of opposition and was allowed to expire after six months.

 Biotech companies also patent their seeds, meaning that if a farmer’s crops are pollinated by a neighbor’s GM crops, he may be sued for harvesting and replanting his own seeds.

Many nations label GM foods  More than 60 nations require GM foods to be

labeled, but the United States does not.  Ballot measures to require labeling have been

defeated by opposition funded by biotech companies.  A 2015 law (nicknamed the “Dark Act”) passed by

the House of Representatives would have removed the right of states to require labeling. This law did not pass the Senate.

Review Questions 5. Scientifically established problems caused by

planting of GM crops DO NOT include a. development of herbicide resistance in plants. b. health hazards in humans from consumption. c. cross-breeding of GM plants with wild plants. d. None of these are scientifically established

problems.

Review Questions 5. Scientifically established problems caused by

problems.

Organic Agriculture  Organic agriculture describes food growing

practices that do not include synthetic pesticides, fertilizers, hormones, or antibiotics.  The Organic Food Production Act of 1990 established

national standards by which foods can be labeled as organic.

 The biggest obstacle for consumers is price.

 Organic products tend to be 10–30% more expensive than conventional products.  Milk can cost twice as much.

Organic agriculture is on the rise  About 80% of Americans buy

organic food at least occasionally, and most retail groceries offer it.

 Both production and demand for organic foods has grown, with some governments (such as the European Union) offering financial incentives to convert to organic agriculture.

Can organic agriculture feed the world?  Meta-analyses have

found that organic agriculture produces yields of roughly 80% of those of conventional agriculture.

 Can organic agriculture support the world population?  Yes, only if food waste and meat consumption are

reduced, and technology improves.

Sustainable Food Production  The path to sustainability includes a spectrum of

solutions that ranges from conventional industrial agriculture to organic agriculture, with biotechnology playing a role, as well.

 Challenges to achieving sustainability include:  Soil degradation  Overconsumption of water  Loss of crop diversity, pollinators, and natural habitats  Reliance on fossil fuels  Greenhouse gas emissions

Locally supported agriculture is growing  The average food

product sold in a U.S. supermarket travels at least 1600 km (1000 mi) from the farm.

 At farmers’ markets, consumers buy meats and produce from local producers.

 In community-supported agriculture (CSA), customers pay farmers in advance for a share, then receive weekly deliveries of produce.

 Food miles alone may not be an accurate way of gaging fossil fuel use, as a large shipment by barge or rail may use less fossil fuels than a small local truck.

 A life-cycle analysis examines all inputs and outputs across all stages of an item’s production, sale, and use to determine fossil fuel consumption.  Food miles contribute just 4–5% of total greenhouse

gas emissions.  About 83% of greenhouse gas emissions occur at the

farm or feedlot, primarily from producing animal products.

Sustainable agriculture mimics natural ecosystems  Ecosystems use cycles and negative feedback

loops, providing a good model for agriculture.  Aigamo rice farming in Japan is an example of this.  Each spring, after planting rice, aigamo ducklings are

released into the rice paddies.  The ducklings eat weeds that compete with the rice,

and insects and snails that eat the rice.  Waste produced by the ducklings fertilizes the water,

and their paddling oxygenates it.  The ducks are removed and sold when the rice forms

 The Azolla fern is also added to provide food for ducks and fish in the paddies, increasing production.

 The end result is a highly productive ecosystem in which pests and weeds are transformed into resources that yield multiple types of organic foods.

 Two hectares of paddies can annually produce:  7 tons of rice  300 ducks  4000 ducklings  Enough vegetables to feed 100 people

Review Questions 6. Which of these modern farming methods would be

permissible under organic certification laws? a. Application of chemical pesticides to kill insects and

weeds b. Synthetic fertilizers to increase the nutrient level of

the soil c. Biocontrol methods, such as the introduction of a

predator species to control a pest d. None of these can be used under USDA rules for

organic certification.

Review Questions 6. Which of these modern farming methods would be

permissible under organic certification laws? a. Application of chemical pesticides to kill insects and

weeds b. Synthetic fertilizers to increase the nutrient level of

the soil c. Biocontrol methods, such as the introduction of

a predator species to control a pest d. None of these can be used under USDA rules for

organic certification.

Slide Number 1
Lecture objectives
Lecture objectives
Can Organic Farming and GMOs Coexist?
Slide Number 5
The Race to Feed the World
We face undernutrition, overnutrition, and malnutrition
Slide Number 8
Slide Number 9
The Green Revolution boosted agricultural production
Industrialized agriculture has brought mixed consequences
Slide Number 12
Slide Number 13
How can we achieve sustainable agriculture?
Review Questions
Review Questions
Review Questions
Review Questions
Raising Animals for Food
Our food choices have environmental consequences
Slide Number 21
Slide Number 22
Feedlots have benefits and costs
Slide Number 24
We use aquaculture to raise seafood
Slide Number 26
Aquaculture brings benefits and costs
Slide Number 28
Review Questions
Review Questions
Preserving Crop Diversity and Pollinators
Slide Number 32
Seedbanks are living museums
Bee declines make pollinator conservation urgent
Slide Number 35
Controlling Pests and Weeds
We have developed thousands of chemical pesticides
Pesticides boost food production but also have negative impacts
Slide Number 39
Pests evolve resistance to pesticides
Slide Number 41
Biological control pits one organism against another
Slide Number 43
Biocontrol agents themselves can become pests
Integrated pest management combines biochemical and chemical methods
Review Questions
Review Questions
Genetically Modified Food
Slide Number 49
Genetic engineering is both like—and unlike—traditional breeding
Biotechnology is transforming the products around us
Slide Number 52
Slide Number 53
What are the benefits of GM crops?
Slide Number 55
Slide Number 56
What are the risks of GM crops?
Public debate over GMOs continues
Slide Number 59
Many nations label GM foods
Review Questions
Review Questions
Organic Agriculture
Slide Number 64
Organic agriculture is on the rise
Can organic agriculture feed the world?
Sustainable Food Production
Locally supported agriculture is growing
Slide Number 69
Sustainable agriculture mimics natural ecosystems
Slide Number 71
Slide Number 72
Review Questions
Review Questions