Nitrogen in crop production: An account of global flows

  title={Nitrogen in crop production: An account of global flows},
  author={Vaclav Smil},
  journal={Global Biogeochemical Cycles},
  pages={647 - 662}
  • V. Smil
  • Published 1 June 1999
  • Environmental Science
  • Global Biogeochemical Cycles
Human activities have roughly doubled the amount of reactive N that enters the element's biospheric cycle. Crop production is by far the single largest cause of this anthropogenic alteration. Inorganic fertilizers now provide 80 Tg N yr−1 (Tg = 1012 g), managed (symbiotic) biofixation adds about 20 Tg N yr−1, and between 28 and 36 Tg N yr−1 are recycled in organic wastes. Anthropogenic inputs (including N in seeds and irrigation water) now supply about 85% of 170 (151–186) Tg N reaching the… 

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