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IDSB02 Readings Nutrient Imbalances in Agricultural Development.docx

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Department
Political Science
Course
POL469H1
Professor
M.Isaac
Semester
Winter

Description
IDSB02 Readings – Nutrient Imbalances in Agricultural Development P.M. Vitousek - 2009  Nitrogen and phosphorous are necessary for high crop yields but downwind and downstream losses of them diminish environmental quality and human well being  Agricultural nutrient imbalances differ with economic development o Ex. Sub-Saharan Africa inputs are inadequate to maintain soil fertility  National and regional policies contribute to patterns of nutrient use and consequences in these situations  Solutions to these nutrient challenges (excess/limiting) can be informed from analyses of trajectories of change within and across agricultural systems  Harvesting crops removes nitrogen and phosphorous & other nutrients  Require replenishing either through biological processes like nitrogen fixation/addition of animal wastes or mineral fertilizer  fertilizer main pathway of nutrient addition its doubled quantities of N&P in terrestrial biospheres  this has helped keep crop production ahead of population growth and can enhance rural economic development but has costs of nutrient pollution (downstream water quality, eutrophication, photochemical smog, increases of GHG nitrous oxide)  in sub-Saharan Africa crop yields have not increased substantially – unlike most other places in the world ->nutrient additions don’t replenish soil nutrients that are extracted from crop harvest  this is seen in Kenya  system persists by drawing down the nutrient capital of what was once high-fertility soil  China: agricultural production increased dramatically since 1975  Policy driven increases in fertilizer use contributed to rising crop yields as they strived for food security  The fertilizer additions far exceeded the amounts used in Europe and USA -> lots lost to the environment degrading the air and water quality  N&P fertilizers in the US contributed to rising crop yields since the 1940s 
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