lect03-25-10

lect03-25-10 - Readings (March 30 April 1) Miller and...

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Unformatted text preview: Readings (March 30 April 1) Miller and Spoolman, Chapters 12 & 10 Kates, R. "Ending Hunger: Current Status and Future Prospects" Consequences, 1996 "The Future of Forests: Tree-Lover, Spare the Woodman" The Economist, June 22, 1991 Green Revolution the green revolution refers to a technological change that allows substantially more food to be produced on the same amount of land (increased yields per unit area of cropland) the process has three main components: (1) developing & planting monocultures of selectively bred or genetically engineered, highyield varieties of crops (2) growing & protecting crops with large inputs of fertilizer, pesticides, & water (3) increasing the intensity & frequency of cropping positive and negative aspects of green revolution Regions Impacted by Green Revolution World Grain Production World Grain Production Per Capita World Meat Production World Meat Production Per Capita U.S. Agriculture U.S. is a major producer of several crops (e.g., corn, wheat, cotton, soybeans) and livestock mechanization and high-yielding varieties have more than doubled agricultural production since 1940, while using less land under 2% of U.S. population lives on farms - 650,000 full time farmers U.S. agriculture is highly productive - each farmer feeds & clothes 140 people (105 domestic, 35 foreign) U.S. residents spend about 2% of their income on domestically produced food, compared to 40% - 70% in many developing countries U.S. Agriculture agricultural system as a whole (including processing & distribution) is largest industry in U.S. - generates 18% of GDP, provides 19% employment in private sector areas of concern include loss of topsoil, lack of genetic diversity & crop variety, vulnerability to pests & diseases, excessive reliance on chemicals there is growing interest in organic food and low-input (sustainable) agriculture Developing Country Agriculture agriculture in developing countries is typically less mechanized and less productive population growth and poverty put more pressure on land, leading to higher rates of erosion & desertification green-revolution techniques (if applied intelligently) may help avoid cultivation on fragile lands, thereby increasing incomes in a sustainable way (Mellor) land-tenure insecurity leads to low productivity & nonsustainability (Prosterman, et al.) Protection Against Pests a pest is any species that competes with humans for food, spreads disease, damages property, or is a nuisance in other ways pesticides are chemicals used to kill undesirable organisms types of pesticides: insecticides - insect killers herbicides - plant killers fungicides - fungus killers nematocides - roundworm killers rodenticides - rat & mouse killers History & Characteristics of Pesticides 1st generation pesticides - mostly natural substances obtained from plants (e.g., pyrethrum, rotenone) 2nd generation pesticides - synthetic organic chemicals developed since 1939 (e.g., DDT, atrazine) pesticides vary in spectrum and persistence broad-spectrum - toxic to many species, narrowspectrum (selective) - toxic to a narrowly defined group high persistence - remain in the environment for an extended period of time, low persistence - dissipate in a few days Use of Pesticides most pesticide use is in developed countries 90% of insecticides & 80% of herbicides applied to crops in the U.S. are used for growing cotton & corn the U.S. lawn is doused with ten times more pesticides per hectare than cropland Case in Favor of Pesticides pesticides save human lives - pesticides kill disease-carrying insects pesticides increase food supplies & lower costs - approximately 55% of the world's food supply is lost to pests pesticides increase profits for farmers - use of pesticides increases crop yields pesticides work faster & better than alternatives new pesticides are used at low rates Case Against Pesticides pests develop genetic resistance to pesticides broad-spectrum insecticides kill the natural predators & parasites of the target pest farmers may find themselves on a pesticide treadmill more and more pesticides are needed as their effectiveness goes down pesticides may harm consumers, farm-workers & their families, and wildlife pesticides pollute water supplies and may also enter the food chain ...
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