- Global boundary: 62 Tg N/year
- Source: *Steffen, W., K. Richardson, J. Rockström, S.E. Cornell, et.al. 2015. Planetary boundaries: Guiding human development on a changing planet. Science 347: 736, 1259855
- Overall, the fixation of nitrogen through Haber–Bosch (120 Tg N yr−1) in 2010 was double the natural terrestrial sources of Nr (63 Tg N yr−1).
- The overall magnitude of anthropogenic relative to natural sources of fixed nitrogen (210 Tg N yr−1 anthropogenic and 203 Tg N yr−1natural) is so large it has doubled the global cycling of nitrogen over the last century.
- The overall magnitude of anthropogenic relative to natural sources of fixed nitrogen (210 Tg N yr−1 anthropogenic and 203 Tg N yr−1 natural) is so large it has doubled the global cycling of nitrogen over the last century.
- Source: Fowler, et al., The global nitrogen cycle in the twenty-first century, Philos Trans R Soc Lond B Biol Sci. 2013 Jul 5; 368(1621): 20130164.
The supply of Nr–reactive nitrogen (NH3, NH4, NO, NO2, HNO3, N20, HONO, PAN and other organic N compounds) is essential for all life forms, and increases in nitrogen supply have been exploited in agriculture to increase the yield of crops and provide food for the growing global human population. It has been estimated that almost half of the human population at the beginning of the twenty-first century depends on fertilizer N for their food. (Source: Fowler, et al.)
As nitrogen is a major nutrient, changes in its supply influence the productivity of ecosystems and change the competition between species and biological diversity. Nitrogen compounds as precursors of tropospheric ozone and atmospheric particulate material also degrade air quality. Their effects include increases in human mortality, effects on terrestrial ecosystems and contribute to the radiative forcing of global and regional climate. (Source: Lee, et al., see figure below)
|Nitrogen Stores & Fluxes||Published Estimates 1990’s||Published Estimates 2000’s|
|Biological N Fixation||112; 139|
|Haber-Bosch (Synthetic fetilizers)||100||120|
|Fluxes to the ocean||48||45|
|Fluxes to the atmosphere||189|
|Fluxes to the land storage||60||27|