APES ch. 12
Key Concepts
Methods of producing food
Increasing food production
Soil degradation
Increasing sustainability
Core Case Study: Grains of Hope
or an Illusion?
Vitamin A deficiency in some developing countries leads to
Blindness
Death
1999: Porrykus and Beyer
Genetically engineered rice with beta-carotene and more iron
Is this the answer for malnutrition in these countries?
Golden Rice: Genetically Engineered Strain of Rice Containing Beta-Carotene
12-1 What Is Food Security and Why Is It Difficult to Attain?
Concept 12-1A Many of the poor suffer health problems from chronic lack of food and poor nutrition,
while many people in developed countries have health problems from eating too much food.
Concept 12-1B The greatest obstacles to providing enough food for everyone are poverty, political
upheaval, corruption, war, and the harmful environmental effects of food production.
Nutrition
Chronic undernutrition: Cannot grow or buy enough food to meet basic energy needs
Malnutrition: Deficiencies of protein and other key nutrients
Overnutrition: Food intake exceeds energy use causing excess body fat
Acute Food Shortages Can Lead
to Famines
Famine
Usually caused by crop failures from
Drought
Flooding
War
Other catastrophic events
War and the Environment: Starving Children in Famine-Stricken Sudan, Africa
Many People Have Health Problems from Eating Too Much
Overnutrition
Similar health problems to those who are underfed
Lower life expectancy
Greater susceptibility to disease and illness
Lower productivity and life quality
World Food Production
Food production is leveling off
Creating shortages in developing nations
How Is Food Produced?
Sources of food
Croplands: Produce grains (77% of the food)
Rangeland: Produce meat (16% of the food)
Ocean fisheries: Seafood ( 7% of the food)
Primary plants: wheat, corn, and rice
Primary animals: fish, beef, pork, and chicken
Industrialized Crop Production Relies on High-Input Monocultures
Industrialized agriculture, high-input agriculture
Goal is to steadily increase crop yield
Plantation agriculture: cash crops
Increased use of greenhouses to raise crops
Satellite Images of Greenhouse Land Used in the Production of Food Crops
Major Types of Agriculture
Industrialized agriculture (high-input): Monocultures, high use of fossil fuels, water, fertilizers,
pesticides
Plantation: Industrial agriculture in tropical regions, bananas, coffee, soybeans, cocoa, vegetables
Traditional subsistence agriculture: Produce food mainly for family survival
Traditional intensive agriculture: Food for the family and income
Traditional Agriculture Often Relies on Low-Input Polycultures
Traditional subsistence agriculture
Traditional intensive agriculture
Polyculture
Benefits over monoculture
Slash-and-burn agriculture
Science Focus: Soil Is the Base of
Life on Land
Soil composition
Soil formation
Layers (horizons) of mature soils
O horizon: leaf litter
A horizon: topsoil
B horizon: subsoil
C horizon: parent material, often bedrock
Soil erosion
A Closer Look at Industrialized Crop Production
Green Revolution: increase crop yields
Monocultures of high-yield key crops
E.g., rice, wheat, and corn
Use large amounts of fertilizers, pesticides, and water
Multiple cropping
Second Green Revolution
World grain has tripled in production
Producing Food by Green-Revolution
High-input monoculture
Selectively bred or genetically-engineered crops
High inputs of fertilizer
Extensive use of pesticides
High inputs of water
Multiple cropping: Growing more than one crop per year on a plot
Crossbreeding and Genetic Engineering Can Produce New Crop Varieties
Gene Revolution
Cross-breeding through artificial selection
Slow process
Genetic engineering
Genetic modified organisms (GMOs): transgenic organisms
Crossbreeding and Genetic Engineering Can Produce New Crop Varieties
Age of Genetic Engineering: developing crops that are resistant to
Heat and cold
Herbicides
Insect pests
Parasites
Viral diseases
Drought
Salty or acidic soil
Advanced tissue culture techniques
There May Be Limits to Expanding the Green Revolutions
Can we expand the green revolution by
Irrigating more cropland?
Improving the efficiency of irrigation?
Cultivating more land? Marginal land?
Using GMOs?
Multicropping?
Producing Food by Traditional Techniques
Interplanting : Growing multiple crops on the same plot
Polyvarietal cultivation: Planting several varieties of the same crop
Intercropping: Growing 2 or more different types of crops on a plot (complement each other)
Agroforestry (alley cropping)
Polyculture: Plantings that mature at different times planted at the same time
12-3 What Environmental Problems Arise from Food Production?
Concept 12-3 Food production in the future may be limited by its serious environmental impacts,
including soil erosion and degradation, desertification, water and air pollution, greenhouse gas
emissions, and degradation and destruction of biodiversity.
Producing Food Has Major Environmental Impacts
Harmful effects of agriculture on
Biodiversity
Soil
Water
Air
Human health
Soil Erosion & Degradation
Land degradation: Decreasing the future ability of land to support crops, livestock, or wild species
Soil erosion: The movement of soil components, especially surface litter and topsoil from on place to
another (wind & water)
Loss of soil fertility
Increased sedimentation of waterways
Soil Erosion in the US
Dust Bowl – 1930s
Soil Erosion act (1935) established the Soil Conservation Service (SCS)
1985 Food Security Act established a strategy for reducing soil erosion
Reductions in erosion since 1987
Causes of Desertification
Overgrazing
Deforestation
Erosion
Salinization
Soil Compaction
Climate Change
Soil Degradation
Salinization: Accumulation of salts in the upper layers of soil. Caused by excessive irrigation
Waterlogging: Large amounts of water are irrigated to leach salts. The excess water raises the water
table raising the saline water up to the root systems of plants
Severe Salinization on Heavily Irrigated Land
Reducing and Cleaning Up Salinization
Reduce irrigation
Switch to salt-tolerant crops
Flush soils
Not growing crops for 2-5 years
Install underground drainage
Solutions: Soil Conservation
Conventional-tillage
Conservation tillage
Terracing
Contour farming
Strip and alley cropping
Windbreaks
Land Classification
Soil Restoration
Organic fertilizer
Animal manure
Green manure
Compost
Crop rotation
Commercial inorganic fertilizer
12-4 How Can We Protect Crops from Pests More Sustainably?
Concept 12-4 We can sharply cut pesticide use without decreasing crop yields by using a mix of
cultivation techniques, biological pest controls, and small amounts of selected chemical pesticides as a
last resort (integrated pest management).
Nature Controls the Populations of
Most Pests
What is a pest?
Natural enemies—predators, parasites, disease organisms—control pests
In natural ecosystems
In many polyculture agroecosystems
What will happen if we kill the pests?
Pests
Compete with humans for food
Invade lawns and gardens
Destroy wood in houses
Spread disease
Are a nuisance
May be controlled by natural enemies
Natural Capital: Spiders are Important Insect Predators
Pesticides: Types
Chemicals that kill undesirable organisms
Insecticides
Herbicides
Fungicides
Rodenticides
We Use Pesticides to Try to Control
Pest Populations
First-generation pesticides
Second-generation pesticides
Paul Muller: DDT
Benefits versus harm
Broad-spectrum agents
Persistence
First Generation Pesticides
Primarily natural substances
Sulfur, lead, arsenic, mercury
Plant extracts: nicotine, pyrethrum
Second Generation Pesticides
Primarily synthetic organic compounds
Broad-spectrum agents
Narrow-spectrum agents
Persistence in the environment
Individuals Matter: Rachel Carson
Biologist
Silent Spring
Potential threats of uncontrolled use of pesticides
Modern Synthetic Pesticides Have Several Advantages
Save human lives
Increases food supplies and profits for farmers
Work quickly
Health risks are very low relative to their benefits
New pest control methods: safer and more effective
Modern Synthetic Pesticides Have Several Disadvantages
Accelerate the development of genetic resistance to pesticides by pest organisms
Expensive for farmers
Some insecticides kill natural predators and parasites that help control the pest population
Pollution in the environment
Some harm wildlife
Some are human health hazards
Modern Synthetic Pesticides Have Several Disadvantages
David Pimentel: Pesticide use has not reduced U.S. crop loss to pests
Loss of crops is about 31%, even with 33-fold increase in pesticide use
High environmental, health, and social costs with use
Use alternative pest management practices
Pesticide industry refutes these findings
Characteristics of an Ideal Pesticide
Affects only target pests
Harms no other species
No genetic resistance
Breaks down quickly in the environment
Be more cost-effective than doing nothing
The Case Against Pesticides
Genetic resistance
The pesticide treadmill
Can kill non-target and natural control species
Can cause an increase in other pest species
Pesticides do not stay put
Can harm wildlife
Potential human health threats
Pesticide Regulation in the United States
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
EPA Evaluation of chemicals
Tolerance levels
Inadequate and poorly enforced
Food Quality Protection Act (FQPA)
There Are Alternatives to Using Pesticides
Fool the pest
Provide homes for pest enemies
Implant genetic resistance
Bring in natural enemies
There Are Alternatives to Using Pesticides
Use insect perfumes
E.g., pheromones
Bring in hormones
Scald them with hot water
Solutions: An Example of Genetic Engineering to Reduce Pest Damage
Natural Capital: Biological Pest Control
Integrated Pest Management Is a Component of Sustainable Agriculture
Integrated pest management (IPM)
Coordinate: cultivation, biological controls, and chemical tools to reduce crop damage to an
economically tolerable level
Disadvantages?
Environmental Effects of Food Production
Biodiversity loss
Soil degradation: ~30% of cropland degraded, 17% is seriously degraded
Air pollution
Water shortages and erosion
Human health
Increasing World Crop Production
Crossbreeding and artificial selection?
Genetic engineering (gene splicing)?
Genetically modified organisms (GMOs)?
Continued Green Revolution techniques?
Introducing new foods?
Working more land?
Meat Production and Consumption Have Grown Steadily
Animals for meat raised in
Pastures
Feedlots
Meat production increased fourfold between 1961 and 2007
Demand is expected to go higher
Industrialized Meat Production
Producing More Meat
Feedlots
Rangelands
Efficiency
Improved rangeland management
Environmental consequences
Government Agricultural Policy
Artificially low prices
Subsidies
Elimination of price controls
Food aid
All are used to help ensure farmers will provide a reliable food supply
Use Government Policies to Improve Food Production and Security
United Nations Children’s Fund (UNICEF) suggests these measures
Immunizing children against childhood diseases
Encourage breast-feeding
Prevent dehydration in infants and children
Provide family planning services
Increase education for women
Solutions: Sustainable Agriculture
Low-input agriculture
Organic farming
Profitable
Increasing funding for research in sustainable techniques
Shift to More Sustainable Agriculture
Paul Mader and David Dubois
22-year study
Compared organic and conventional farming
Benefits of organic farming
Shift to More Sustainable Agriculture
Strategies for more sustainable agriculture
Research on organic agriculture with human nutrition in mind
Show farmers how organic agricultural systems work
Subsidies and foreign aid
Training programs; college curricula
Science Focus: Sustainable Polycultures of Perennial Crops
Polycultures of perennial crops
Wes Jackson: natural systems agriculture benefits
No need to plow soil and replant each year
Reduces soil erosion and water pollution
Deeper roots – less irrigation needed
Less fertilizer and pesticides needed
Buy Locally Grown Food
Supports local economies
Reduces environmental impact on food production
Community-supported agriculture