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Unformatted text preview: Chapter 8- Soils Chapter (con.) (con.) Productive Soil Productive Good supply of nutrients and nutrient holding capacity Infiltration, good waterholding capacity, resists evaporative water loss Porous structure for aeration Nearneutral pH Low salt content The Soil Community: “The living soil” soil” Humus Humus Partly decomposed organic matter High capacity for holding water and nutrients Typically found in O horizon The Importance of Humus to Topsoil Topsoil Soil Degradation Soil Erosion Drylands and Desertification Irrigation and Salinization Three Major Practices That Expose Soil to Erosion Soil Overcultivation Overgrazing Deforestation Causes of Soil Degradation Causes Erosion: Wind or Water Erosion: Splash erosion: impact of falling raindrops breaks up the clumpy structure of topsoil Sheet erosion: running water carries off the fine particles on the soil surface Gully erosion: water volume and velocity carries away large quantities of soil causing gullies (next slide) Desertification Desertification Formation and expansion of degraded areas of soil and vegetation cover in arid, semiarid, and seasonally dry areas, caused by climatic variations and human activities. Desertification Desertification Wind erosion and desert pavement Wind Salinization Salinization A process of distilling out dissolved salts in irrigated water and leaving it on the land. A form of desertification since land is rendered useless Worldwide and estimated 3.7 million acres of agricultural land is lost annually to salinization and waterlogging Flood Irrigation Flood Alternative Farming Practices Alternative Notill planting Shelter belts Contour farming Dry land farming – minimize irrigation Salinization Salinization Osmosis: the movement of water molecules from an area of high concentration to an area of low concentration. – Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. – Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode. – Isotonic Solutions: contain the same concentration of solute as an another solution (e.g. the cell's cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. The fluid that surrounds the body cells is isotonic. No-till farming Machinery No-till Contour Farming Contour Shelterbelts Shelterbelts A Global View of Soil Degradation Degradation Public Policy and Soils Public Subsidies Sustainable agriculture: SARE = Sustainable Agriculture Research and Education Conservation Reserve Program (CRP) Public Policy and Soils Public Farm bills – Federal Agricultural Improvement and Reform Act (FAIR) – Wetlands Reserve Program (WRP) – 2002 Farm Security and Rural Investment Act – Wildlife Habitat Incentives Program (WHIP) – Environmental Quality Incentives Program (EQIP) Helping Individual Landowners Helping Sustainable Agriculture and Rural Development Initiative (SARD): coordinates efforts to reach small farmers with sound agricultural practices. Conserving the Soil Conserving Cover the soil Minimal or zero tillage Mulch for nutrients Maximize biomass production Maximize biodiversity Chapter 9 Chapter The Production and Distribution of Food Crops and Animals: Major Patterns of Food Production of The development of modern industrialized agriculture The green revolution Subsistence agriculture and the developing world Animal farming and its consequences Increasing food production Humans and agriculture 12,000 YBP Neolithic revolution – Introduction of agriculture and animal husbandry (foundation of civilizations) 14501700 European expansion – Great exchange of plants and animals The Americas: potatoes, corn, tomatoes, squash, etc. Eurasia/Africa: wheat, sugarcane, rice, horses, pigs, sheep, cattle, etc. Humans and agriculture 150 YBP Industrial revolution – Increased mechanization (initially animal powered, early 20th century switched to fossil fuel). – 1950’s saw the introduction of inorganic fertilizes and synthetic pesticides 1970present pesticide use tripled, crop loss to pests – Irrigation becomes the # 1 global water use constant U.S. Crop Yields U.S.
(tons or bushels per acre) The Green Revolution Goal was to export U.S. agricultural technology to developing countries
– Success increased agriculture production outpaced population growth and prevented much malnutrition. – Problems Heavy reliance on irrigation and fertilizers. Negative impact on small farmers and culturally specific crops (cash crops for export). population explosions (along with epidemiological transition). Labor intensive Subsistence Farming has its problems problems Use of marginal lands Clearing of tropical rainforests Environmental degradation Loss of 70% of grain crops in U.S. Overgrazing Mismanagement of animal manure Most widespread source of water pollution Source of 3% of greenhouse gases Disease transmission, e.g., avian flu Conversion of tropical rainforest into cattle pasture (fastfood in the 1980’s) Heifer Project International ☺ Animal Farming and Its Consequences Consequences More affluent, more meat Increasing Food Production Increasing Over last 30 years, food production has surpassed population growth World food consumption to increase 50% The need to Increase Food Production Production by 2020 Agricultural sustainability is highly dependent on soil and water conservation Global climate change: Shifting patterns of precipitation (remember soil they don’t move) Biofuels (still run a corn surplus in the U.S.) Main options for increased food production production Greater efficiency Substituting new genetic varieties The promise of biotechnology – Rotating crops – Growing many different kinds of crops – Recycling animal wastes – Grain over animal production (lower on the food chain) Biotech Crops in the United States States Biotech Benefits Soil conservation (notill corn and soybeans Roundup®) Decreased pesticide use (Bt cotton) Greater yields Greater nutritional value Future Objectives of Biotech Crops Future Disease resistance Drought tolerance Improved nutritional value Incorporate human vaccines Environmental Problems Environmental Pest resistance to genetically engineered toxin Broad spectrum impact on non target species “Super weeds” Food Safety Problems Food Proteins that cause allergic responses Antibiotic resistance to human pathogens Plant might produces new toxic substances Other Problems with Biotech Crops Access to new technologies – profit driven – affordability in developing countries – terminator technology: seed sterility Consumer acceptance Patterns in Food Trade Patterns Market driven Global food production greater than basic global needs hunger and malnutrition are found in most countries – Food items are commodities Food Security Nutrition vs. Hunger Nutrition Hunger: lack of basic food for energy and meeting nutritional needs – Malnutrition: lack of essential nutrients (amino acids, vitamins and minerals) – Undernourishment: lack of adequate food energy (Calories) Root Cause of Hunger Root The root cause of hunger is poverty – 20 % of the people on earth suffer from the effects of hunger and malnutrition – Children are most at risk – It is more likely that a pet cat will be fed than an undernourished child
needs of humans. Food production linked to economics not nutritional Civil War interrupts local agriculture, food shortage used Famine: a severe shortage of food accompanied by a significant increase in death rate. Causes of Famine
as power Famine and Hunger Hotspots Famine Drought longterm lack of precipitation Government Incompetence Food Aid Food
“Give a man a fish; you have fed him for today. Teach a man to fish; and you have fed him for lifetime." --Old Chinese Saying Closing Thoughts Closing “The United States needs to make the elimination of hunger the primary focus of its relations with the developing world.” (1980 Presidential Commission on World Hunger) The right to food must be considered a basic human right (How does that make you feel?) ...
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This note was uploaded on 02/17/2011 for the course BIOL 270 taught by Professor Jones during the Spring '06 term at South Carolina.
- Spring '06