AP ENVS. MONDAY DEC 17 2013. CONT CHAP 9: SOILS AND AGRICULTURE. From p.233 Extreme soil erosion = “desertification”. DESERTIFICATION. Encroachment of the Sahara USDA: Http://bit.ly/18KHQo3. SBTS: Measuring Erosion with Pins.....and Nuclear Fallout?!. READING: pp. 236-237.
AP ENVS MONDAY DEC 17 2013
CONT CHAP 9: SOILS AND AGRICULTURE • From p.233 • Extreme soil erosion = “desertification”
DESERTIFICATION • Encroachment of the Sahara • USDA: Http://bit.ly/18KHQo3
SBTS: Measuring Erosion with Pins.....and Nuclear Fallout?! • READING: pp. 236-237 left off 12/16
SBTS • A simple and low-tech but still useful way to measure soil erosion is to use a set of _____ _____. • One measures from the top of the _____ to the eroded ________. • One also needs to use ______ of these _____ _____, and to make multiple measurements over ______.
SBTS • Another, more modern way to measure soil erosion is to measure the trace levels of _______________ due to widespread nuclear ________. • These radioactive background levels are due to many years of above-ground nuclear _______ previously conducted throughout the world, followed by erosion, wind-blown dusts, and finally ________. • The basis behind this method is the assumption that stable soils will show a _________ level of radiation, while eroding soils will show a pattern of both ____ and _____ levels. • The radioactive isotope used for this method is: __________.
IRRIGATION + FERTILIZERS = ???? • Nutrient runoff (inorganic fertilizers) • Eutrophication!
INORGANIC v ORGANIC FERTILIZER • INORGANIC • Nitrates, Phosphates • HOMELAND SECURITY! • Water soluble N, P • ORGANIC • Manure • Animal wasteproducts • N, P in less soluble organic form • Lessens nutrient runoff
OVERGRAZING HAS MANY NEGATIVE CONSEQUENCES: “Feedback Loops” (Chap 5)
AGRICULTURAL POLICY • 38% of Earth’s terrestrial surface is used for Ag! • 26%: grazing “rangeland” • U.S. Bureau of Land Management (BLM) • Low grazing fees • 12%: cropland
Wetlands have been drained for farming • Wetlands = swamps, marshes, bogs, river floodplains • Over 50% have been drained for agriculture in the U.S. • Government policy encouraged draining • Swamp Lands Acts (1849, 1950, 1860) = drained and converted wetlands to control floods and malaria • Wetlands are now seen as vital ecosystems • Habitat, flood control, recharged water supplies • Despite regulations, loopholes allow wetland losses • Wetlands Reserve Program = landowners are paid to protect, restore, and enhance wetlands...latest farm bill
U.S. programs promote soil conservation Conservation Reserve Program (1985): farmers are paid to put highly erodible land in conservation reserves Trees and grasses are planted instead of crops Each dollar spent saves 1 ton of topsoil Generates income for farmers Improves water quality Provides habitat for native wildlife The 2008 farm bill limited reserve lands to 32 million acres But funds 14 other similar land conservation programs
International soil conservation programs Food and Agriculture Organization (FAO) = the United Nations’ main agricultural program The FAO’s Farmer-Centered Agricultural Resource Management Program (FARM) Supports innovative approaches to resource management and sustainable agriculture in Asia Helps farmers duplicate agricultural success stories Uses local communities to educate and encourage farmers to conserve soils and secure the food supply
END OF CHAPTER 9 END OF UNIT: EARTH’S SYSTEMS & RESOURCES
UNIT 3: THE LIVING WORLD • Chapters 3, 4, 5 (15) • Population Level ----- Community/Ecosystem ----- Species • Chapter 3: • EVOLUTION! • Charles Darwin and the voyage of the Beagle • Speciation and biodiversity • Mass extinctions: K-T, 65 million years