1. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Food and Agriculture
Chapter 11
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

2. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Outline:
Nutrition and Food Supplies
Major Food Sources
Soil
Structure
Erosion
Agricultural Resources
Water
Energy
Genetic Engineering
Sustainable Agriculture
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

3. NUTRITION AND FOOD SUPPLIES
World food supplies have more than kept up with human population growth over the past two centuries.
billion people - average daily diet was less than 2,000 calories/person.
billion people - world food supply can provide more than 2,500 calories/person.
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4. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Nutrition
The most common dietary problem in wealthy countries is over-nutrition.
In NA and Europe, average daily caloric intake is 3,500 calories.
Sub-Saharan Africa has not kept food production up to pace of population growth.
Collapse of Soviet Union also led to significant collapse in food production.
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5. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

6. Chronic Hunger and Food Security
About 1 in 5 people in the developing world are considered chronically hungry.
200 million children
Can lead to permanently stunted growth, mental retardation, and other developmental disorders.
Poverty is the greatest threat to food security (The ability to obtain sufficient food on a daily basis).
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7. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Essential Nutrients
Malnourishment - Nutritional imbalance caused by a lack of specific dietary components.
In poorer countries, people often cannot afford to purchase an adequate variety of foods, including meats and vegetables.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

8. Risk of Inadequate Nutrition
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

9. Protein Deficiency Diseases
Kwashiorkor - “Displaced Child” - Occurs mainly in children whose diet lacks high-quality protein.
Reddish-orange hair, bloated stomach
Marasmus - “To Waste Away” - Caused by a diet low in both protein and calories.
Very thin, shriveled
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10. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Iron deficiency is the most common dietary imbalance in the world.
Leads to anemia.
Increases risk of death from hemorrhage in childbirth and affects development.
Red meat, eggs, legumes, and green vegetables are all good sources of iron.
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11. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Famines
Famines are characterized by large-scale food shortages, massive starvation, social disruption, and economic chaos.
Mass migrations often occur because productive capacity has been sacrificed.
Environmental conditions are immediate trigger, but politics and economics are often underlying problems.
Arbitrary political boundaries block historic access to refuge areas.
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12. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Famines
Aid policies of rich countries often serve to distribute surplus commodities and produce feeling of generosity.
Food camps have serious drawbacks:
Stress and crowding
Lack of sanitation
Close contact to epidemic diseases
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13. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
MAJOR FOOD SOURCES
Three crops deliver majority of world’s nutrients:
Wheat, Rice and Corn
Potatoes, barley, oats and rye are staples in cool, moist climates.
Cassava, sweet potatoes, and other roots and tubers are staples in warm wet climates.
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Meat and Milk
Meat and Milk distribution highly inequitable.
More developed countries make up 20% of world population, but consume 80% of meat and milk production.
60% of production occurs in lesser developed countries.
90% of grain grown in NA is used to feed livestock.
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15. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Meat
Every 16 kg of grain and soybeans fed to beef cattle in feedlots produce about 1 kg of edible beef.
If we ate the grain directly, we would obtain twenty-one times more calories and eight times more protein than we get from eating the beef.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

16. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Seafood
Seafood is an important protein source.
Since 1989, 13/17 major fisheries have declined or become commercially inviable.
Between , number and average vessel size of world fishing fleet doubled.
Now have twice the capacity needed to extract total annual sustainable harvest.
Catching $70 billion cost $124 billion.
1/4 animals considered by-catch.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

17. SOIL: A RENEWABLE RESOURCE
Soil - A complex mixture of weathered minerals, partially decomposed organic materials, and a host of living organisms.
At least 20,000 different soil types in the US.
Vary due to influences of parent material, time, topography, climate, and organisms.
Can be replenished and renewed.
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18. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Composition
Particle size affects soil characteristics.
Spaces between sand particles give sandy soil good drainage and allow aeration.
Can easily dry out.
Tight packing of small particles in silty or clay soils makes them less permeable to air and water.
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19. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Structure
Soil exhibits wide range of organic content.
Humus - Insoluble residue from partially decomposed plants and animals.
Most significant factor in soil structure.
Activity of organisms living in soil helps create structure, fertility, and cultivation suitability.
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20. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Profiles
Soils are stratified into horizontal layers called soil horizons.
Together make up soil profile.
O Horizon (Organic layer)
Leaf litter, partially decomposed organisms.
A Horizon (Topsoil)
Mineral particles mixed with organic material.
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21. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Profiles
E Horizon (Leached)
Depleted of soluble nutrients.
B Horizon (Subsoil)
Often dense texture from accumulating nutrients.
C Horizon (Parent Material)
Weathered rock fragments with little organic material.
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23. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Types
Soils are classified according to structure and composition (12 Orders):
Mollisols Andiosols
Alfisols Vertisols
Spodosols Histosols
Oxisols Inceptisols
Ultisols Entisols
Aridosols Gelisols
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

24. WAYS WE USE AND ABUSE SOILS
Approximately 11% of the earth’s land area is currently in agricultural production.
Up to four times as much could potentially be converted to agricultural use.
Much of this additional land suffers from constraints.
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25. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Degradation
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Land Resources
In developed countries, 95% of recent agricultural growth has been from altered agricultural practices (pesticides - fertilizer).
Less land cultivated in NA now than 100 years ago.
Many developing countries are reaching limit of lands that can be exploited for agriculture without unacceptable social and environmental costs.
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Land Degradation
Estimated nearly 3 million ha of cropland ruined annually via erosion, 4 million ha transformed into deserts, and 8 million ha converted to non-agricultural uses.
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28. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Land Degradation
Definitions of degradation are based on both biological productivity and expectations of what land should be like.
Generally, land is considered degraded when soil is impoverished or eroded, run-off is contaminated, or biodiversity is diminished.
Water and wind are the driving forces for vast majority of soil degradation.
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29. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Erosion
Erosion is an important natural process, resulting in redistribution of the products of geologic weathering, and is part of both soil formation and soil loss.
Tends to begin subtly.
Worldwide, erosion reduces crop production by equivalent of 1% of world cropland per year.
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30. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Mechanisms of Erosion
Rill Erosion - Small rivulets of running water gather together and cut small channels in the soil.
Gully Erosion - Rills enlarge to form bigger channels too large to be removed by normal tillage.
Streambank Erosion - Washing away of soil from established streambanks.
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31. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Mechanisms of Erosion
Wind can equal or exceed water as an erosive force, especially in a dry climate and on flat land.
Intensive farming practices:
Row crops leave soil exposed
Weed free-fields
Removal of windbreaks
No crop-rotation or resting periods
Continued monocultures
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

32. OTHER AGRICULTURAL RESOURCES
Water
Agriculture accounts for largest single share of global water use.
As much as 80% of water withdrawn for irrigation never reaches intended destination.
Cheap cost encourages over-use.
Waterlogging
Salinization
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Fertilizer
Lack of nitrogen, potassium, and phosphorus often limits plant growth.
Adding nutrients via fertilizer usually stimulates growth and increases crop yields.
Average of 20 kg/ha fertilizer used.
Average of 91 kg/ha fertilizer used.
Manure and nitrogen-fixing bacteria are alternative methods of replenishing soil nutrients.
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34. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Energy
Farming in industrialized countries is highly energy-intensive.
Between , energy use rose directly with mechanization of agriculture, and indirectly with spraying of chemicals.
Altogether, US food system consumes 16% of total energy use.
Most foods require more energy to produce, process, and transport than we yield from them.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

35. NEW CROPS AND GENETIC ENGINEERING
Most of world food comes from 16 widely grown crops.
At least 3,000 species of plants have been used for food at some point in time.
Many new or unconventional varieties might be valuable food supplies.
Winged-bean
Triscale
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36. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Green Revolution
Most major improvements in farm production have come from technological advances and modification of a few well-known species.
Corn yields jumped from 25 bushels per acre to 130 per acre in last century.
Most of gain accomplished through conventional plant breeding.
Also seen rise of dwarf varieties.
Green Revolution - Spread of new varieties around the world.
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Genetic Engineering
Genetically Modified Organisms (GMO’s)
Contain DNA possessing genes borrowed from unrelated species.
Can produce crops with pest-resistance and wider tolerance levels.
Opponents fear traits could spread to wild varieties, and increased expense would largely hurt smaller farmers.
70% of all processed foods in NA contain transgenic products.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

38. SUSTAINABLE AGRICULTURE
Soil Conservation
Managing Topography
Contour Plowing - Plowing across slope to slow flow of water.
Strip Farming - Planting different crops in alternating strips along land contours.
Terracing - Shaping land to create level shelves of earth to hold water and soil.
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39. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Conservation
Providing Ground Cover
Annual row crops cause highest rates of erosion because they leave soil bare for much of the year.
Leave crop residue after harvest.
Plant cover crops after harvest.
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40. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Soil Conservation
Reduced Tillage
Minimum Till - Chisel plow
Conserv-Till - Coulter (Disc)
No-Till - Drilling
Often farmers using conservation tillage must depend relatively heavily on pesticides.
Traditional tillage helped control weeds and pests.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

41. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Summary:
Nutrition and Food Supplies
Major Food Sources
Soil
Structure
Erosion
Agricultural Resources
Water
Energy
Genetic Engineering
Sustainable Agriculture
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

42. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.