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Food and Agriculture Chapter 11 Outline: • • • • • • Nutrition and Food Supplies Major Food Sources Soil Structure Erosion Agricultural Resources Water Energy Genetic Engineering Sustainable Agriculture NUTRITION AND FOOD SUPPLIES • World food supplies have more than kept up with human population growth over the past two centuries. 1950 - 2.5 billion people - average daily diet was less than 2,000 calories/person. 2001- 6.0 billion people - world food supply can provide more than 2,500 calories/person. 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. 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). Essential Nutrients Malnutrition - Nutritional imbalance caused by a lack of specific dietary components such as protein Undernourishment – people who can’t get enough food to meet basic needs Overnutrition – when food intake esceeds energy use and causes excess body fat ( Obesity) Risk of Inadequate Nutrition Protein Deficiency Diseases • • Kwashiorkor - “Displaced Child” - Occurs mainly in children whose diet lacks highquality protein. Reddish-orange hair, bloated stomach Marasmus - “To Waste Away” - Caused by a diet low in both protein and calories. Very thin, shriveled Iron • 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. 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. 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 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. Producing Food by Green-Revolution Techniques High-input monoculture Selectively bred or genetically-engineered crops High inputs of fertilizer Extensive use of pesticides High inputs of water Increased intensity and frequency of cropping Green Revolutions Fig. 13-6 p. 282 First green revolution Second green revolution (developed countries) (developing countries) Major International agricultural research centers and seed banks Figure 13-13 (1) Page 288 Biodiversity Loss Loss and degradation of habitat from clearing grasslands and forests and draining wetland Fish kills from pesticide runoff Killing of wild predators to protect livestock Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains Soil Erosion Loss of fertility Salinization Waterlogging Desertification Figure 13-13 (2) Page 288 Air Pollution Greenhouse gas emissions from fossil Fuel issue Other air pollutants from fossil fuel use Pollution from pesticide sprays Water Aquifer depletion Surface and ground pollution from pest Increased runoff andand fertilizers flooding from land cleared Overfertilization of to grow crops and slow-moving r from runoff of nitra Sediment pollution from phosphates from erosion fertilizers, livestoc wastes, and food Fish kills from pesticide Figure 13-13 (3) Page 288 Human Health Nitrates in drinking water Pesticide residues in drinking water, food, and air Contamination of drinking and swimming water with disease organisms from livestock wastes Bacterial contamination of meat 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. 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. Figure 13-24 Page 298 Areas of highest concentration Figure 13-25 Page 298 Kilograms of grain needed per kilogram of body weight Beef cattle 7 Pigs 4 Chicken 2.2 Fish (catfish or carp) © 2004 Brooks/Cole – Thomson Learning 2 Seafood • • • Seafood is an important protein source. Since 1989, 13/17 major fisheries have declined or become commercially inviable. Between 1970-1990, 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. Seafood • • • Seafood is an important protein source. Since 1989, 13/17 major fisheries have declined or become commercially inviable. Between 1970-1990, 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. Figure 13-30 Page 303 Spotter airplane Trawler fishing Fish farming in cage Purse-seine fishing trawl flap sonar trawl lines fish school trawl bag Fish caught by gills Drift-net fishing Long line fishing lines with hooks floatbuoy 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. 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. 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. 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, runoff is contaminated, or biodiversity is diminished. - Water and wind are the driving forces for vast majority of soil degradation. 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 Fertilizer • Lack of nitrogen, potassium, and phosphorus often limits plant growth. Adding nutrients via fertilizer usually stimulates growth and increases crop yields. - 1950 - Average of 20 kg/ha fertilizer used. - 1990 - Average of 91 kg/ha fertilizer used. Manure and nitrogen-fixing bacteria are alternative methods of replenishing soil nutrients. Energy • Farming in industrialized countries is highly energy-intensive. Between 1920-1980, 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. 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 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. 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. 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. 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. 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.