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10
Creating a Sustainable
System of Agriculture to
Feed the World’s People
Chapter Outline
Hunger, Malnutrition, Food Supplies, and the Environment
Hunger, Poverty, and Environmental Decay
Declining Food Supplies
The Challenge Facing World Agriculture: Feeding People/Protecting the Planet
Understanding Soils
What is Soil?
How Is Soil Formed?
What Is a Soil Profile?
Barriers to a Sustainable Agricultural System
Soil Erosion
Desertification
Farmland Conversion
Declines in Irrigated Cropland
Waterlogging and Salinization
Declining Genetic Diversity in Crops and Livestock
Solutions: Building a Sustainable Agricultural System
Protecting Existing Soil and Water Resources
Soil Enrichment Programs
Increasing the Amount of Land in Production
Increasing the Productivity of Existing Land: Developing Higher-Yield Plants and Animals
Protecting Wild Plant Species: Habitat Protection and Germ Plasm Repositories
Developing Alternative Foods: Native Species as Sustainable Food Sources
Fish from the Sea and Aquaculture
Eating Lower on the Food Chain
Reducing Pest Damage and Spoilage
Legislation and New Policies: Political and Economic Solutions
Key Terms
sustainable agriculture undernourished malnourished
infectious diseases kwashiorkor marasmus
soil parent material soil profile
horizons litter layer topsoil
humus subsoil soil erosion
natural erosion accelerated erosion desertification
farmland conversion waterlogging water table
salinization Green Revolution subsidies
minimum tillage herbicides contour farming
strip cropping terracing shelterbelts
organic fertilizers green manure synthetic fertilizer
crop rotation hybrids selective breeding
genetic engineering germ plasm repositories overfishing
fish farms aquaculture mariculture
Objectives
1. Define the following terms: “undernourished,” “malnourished,” “kwashiorkor,” and “marasmus.”
2. Discuss how hunger and malnutrition are related to environmental degradation.
3. Discuss the trend in per capita grain production and its ramifications for human populations.
4. Define the following terms: “soil,” “parent material,” “topsoil,” “litter layer,” “humus,” and “subsoil.”
5. List the five major soil horizons and their common names.
6. Define the following barriers to sustainable agriculture and describe their impact on the agricultural system: “soil erosion,” “desertification,” “farmland conversion,” “declines in irrigated cropland,” “waterlogging,” “salinization.”
7. Discuss the successes and failures of the Green Revolution.
8. List the techniques used in soil conservation.
9. Discuss how water can be used more efficiently on irrigated croplands.
10. Discuss the different types of soil enrichment used today and their advantages.
11. Discuss the techniques used to increase productivity of crops and livestock.
12. Discuss the importance of maintaining genetic diversity in food crops and in our genetic repositories.
13. Summarize the sources of alternative foods available to human populations.
14. Define the following terms: “overfishing,” “fish farms,” “aquaculture,” and “mariculture.”
15. Discuss why eating lower in the food chain could provide more food for the world’s human population.
16. Discuss the significance of food loss by pest damage and spoilage.
Lecture Outline
Hunger, Malnutrition, Food Supplies, and the Environment - Hunger is widespread; it is especially prevalent in Asia, Africa, and Latin America. Large percentages of the populations of poor countries suffer from some combination of malnourishment and undernourishment.
A. Diseases of Malnutrition - Millions of people die yearly from malnutrition and undernourishment.
1. Kwashiorkor - Protein-deficiency disease, or kwashiorkor, strikes children soon after weaning.
2. Marasmus - Protein- and calorie-deficiency produce marasmus. Less obvious effects of moderate malnutrition include decreased immunity.
B. Hunger, Poverty, and Environmental Decay - Severe malnutrition produces serious and permanent mental and physical impairment.
C. Declining Food Supplies - Global warming and soil erosion/deterioration have led to declining per capita food production over the past decade.
D. The Challenges Facing World Agriculture: Feeding People/Protecting the Planet - A sustainable system of agriculture is needed to meet the present and future needs for food and to protect soil and water.
Understanding Soils
A. What is Soil? Soils are mixtures of organic and inorganic materials varying in a number of features.
B. How Is Soil Formed? A variety of physical processes and organisms contribute to soil formation from parent material.
C. What is a Soil Profile? Soils have layers that differ in type and thickness between different soil types. Climate, geological features, biotic factors, and age determine a given region's soil profile.
Barriers to a Sustainable Agricultural System
A. Soil Erosion - This is the most serious agricultural problem today.
1. Accelerated erosion largely results from human activities such as overgrazing or unsustainable cultivation practices. Accelerated erosion not only destroys productivity but also contributes heavily to air and water pollution problems.
2. Natural erosion occurs in areas in the absence of human intervention.
B. Desertification: Turning Cropland to Desert - Global climate change and mistreatment of soils in arid regions leads to desertification. Previous civilizations have caused desertification; today, the problem is widespread, but particularly bad in Africa.
C. Farmland Conversion - Farmland is lost as urbanization, energy production, transportation, and other forms of development take land out of agricultural production; this is known as farmland conversion.
D. Declines in Irrigated Cropland - The amount of irrigated cropland per capita is on the decline. Measures that increase the efficiency of water use may prove helpful in providing an adequate supply of irrigation water.
E. Waterlogging and Salinization
1. Waterlogging occurs when too much water is applied to a crop. Worldwide about one-tenth of the irrigated cropland suffers from waterlogging.
2. Salinization is the accumulation of salts and minerals in the soil that occurs after irrigation. Evaporation will concentrate the salts and minerals in the soil over time and reduce productivity. About one-fourth of the irrigated farmland worldwide suffers from salinization.
F. Declining Genetic Diversity in Crops and Livestock
1. Green Revolution - New varieties of crops, such as those introduced in the Green Revolution, have substantially increased yield but decreased genetic diversity of crop plants; this increases vulnerability to pests, disease organisms, and environmental stress.
2. Habitat Destruction - Local varieties that are well adapted to regional sites are at risk of loss because of lack of use and propagation. This is the largest source of genetic crop diversity. Monoculture has increased the risk of large losses in productivity as a result of pest infestation.
G. Politics, Agriculture, and Sustainability
1. Government policies have not always fostered sustainable use of agricultural systems. Subsidies have contributed to unsustainable agricultural practices and have just been recently changed. Laws and policies must be systematically examined and revised with global sustainability in mind.
Solutions: Building a Sustainable Agricultural System - Creating a sustainable agricultural system will require a multifaceted approach, including measures to slow and perhaps stop human population growth.
A. Protecting Existing Soil and Water Resources
1. Soil conservation: six strategies for the basis for sustainable practices to control soil erosion.
a. Minimum Tillage or Conservation Tillage
b. Contour Farming
c. Strip Cropping
d. Terracing
e. Gully Reclamation
f. Shelterbelts
2. Overcoming the Economic Obstacles to Soil Erosion Controls
a. Government incentives for farmers to practice good, sustainable agriculture.
b. The 1985 farm bill was a step in the right direction but concerns are that it may be diluted by further legislation.
3. Preventing Desertification
4. Reducing Farmland Conversion
5. Saving Irrigated Cropland/Using Water More Efficiently
6. Preventing Salinization and Waterlogging
B. Soil Enrichment Programs - Farming reduces valuable soil nutrients. These can be replaced by sustainable agricultural techniques.
1. Organic Fertilizers
2. Synthetic fertilizers only partially replenish the soil.
3. Crop Rotation
C. Increasing the Amount of Land in Production
1. Development of new varieties of plants and animals.
a. Selective breeding
b. Genetic engineering
D. Protecting Wild Plant Species - Habitat Protection and Germ Plasm Repositories
1. Habitat protection
2. Seed banks
E. Developing Alternative Foods: Native Species as Sustainable Food Sources - Many native plant and animal species would be used to provide food. Native animals offer many benefits over domestic livestock, including their resistance to disease-causing organisms.
F. Fish from the Sea and Aquaculture
1. Many of the world’s commercially important fish stocks are in danger of being depleted.
2. Global efforts are needed to preserve current fish stocks.
3. Commercial fish farming could provide additional food for a growing population.
G. Eating Lower on the Food Chain
1. Developing nations should concentrate on grain production rather than meat.
2. A change in eating habits in the western world could increase the amount of food available for human consumption.
H. Reducing Pest Damage and Spoilage
1. About 30% of all agricultural output is destroyed by pests, spoilage, and diseases.
2. Improvements in storage and transportation can reduce food loss.
I. Legislation and New Policies: Political and Economic Solutions
1. Solving world hunger and creating a sustainable system of agriculture will require dramatic changes in government policies worldwide.
Suggestions for Presenting the Chapter
· Instructors should emphasize that adequate nutrition for the world’s peoples is not just a social or moral issue. Nutrition has important biological ramifications in human ecology and will directly or indirectly affect the environment.
· Instructors should emphasize that the dependency on technology fostered by the Green Revolution is not the ultimate solution to our agricultural problems. The movement to sustainable production must be made if the people of the world are going to be fed and the land is going to remain productive for future generations. The goal should be long-term sustainable production not short-term profit.
· Instructors are encouraged to investigate local agricultural practices and inform the students about them. This can be achieved by field trips, speakers, and class discussion.
· Visiting local supermarkets and examining the sources of produce and the availability of organically produced fruits, vegetables, and meat is an informative class project. What foods available in your local stores are produced locally? What foods are organically produced? Why should we seek to purchase organically produced foods? What are important local sources of organic food?
· Explore the topic of organic gardening with your students. How many students participate in gardening? Does your institution have a garden plot? What are the advantages of growing your own food? Why is organic gardening a sustainable activity?
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