Nitrogen key facts

"Before humanity began exploiting Haber-Bosch and other nitrogen-fixation techniques, the amount of reactive nitrogen produced in the world was balanced by the activity of another small bacterial group that converts reactive nitrogen back to N2 gas in a pross called denitrification. In only one human generation, though, that delicate balance has been transformed completely. By 2005 humans were creating more than 400 billion pounds of reactive nitrogen each year, an amount at least double that of all natural processes on land combined" (p. 66) "a recent scientific assessment ranked nitrogen pollution as one of the top three threats to biodiversity around the globe" (p. 67) "If Americans were to switch to a typical Mediterranean diet, the country's fertilizer use would be cut in half" (p. 67) "Although N2O is far less abundant in the atmosphere than CO2 is, its current atmospheric concentration is responsible for warming equivalent to 10 percent of CO2's contribution" (p. 68) "Of the nitrogen that ends up in crop plants, most goes into the mouths of pigs, cows and chickens--and much of that is then expelled as belches, urine and feces" (p. 69) "On the energy side, which represents about 20 percent of the world's excess nitrogen, much reactive nitrogen could be removed from current fossil-fuel emissions by better deployment of NOx-scrubbing technologies" (p. 69) "The average farmer in the breadbasket of the upper U.S. Midwest (the source of the great majority of nitrogen pollution fueling the Gulf of Mexico dead zones) typically uses 20 to 30 percent more nitrogen fertilizer than agricultural extension agents recommend" (p. 70).

Source: Alan R. Townsend and Robert W. Howarth, “Fixing the Global Nitrogen Problem,” Scientific American, (2010): 64-71, accessed April 24, 2014,

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