The Benefits and Environmental Costs of Anthropogenic Reactive Nitrogen

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Explore the impacts of anthropogenic reactive nitrogen on the environment, including its benefits such as food productivity and vegetation growth, as well as its environmental costs. Learn about managing the nitrogen cycle and potential solutions for better nitrogen fertilizer management.

  • Anthropogenic Nitrogen
  • Environmental Impact
  • Nitrogen Cycle
  • Fertilizer Management
  • Sustainable Agriculture
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  1. The benefits and the environmental costs of anthropogenic reactive nitrogen The 7th ISOME & the 4th IYEF, GuangZhou, 06/12/2013

  2. Outline Non-reactive nitrogen (N2) VS. Reactive Nitrogen (NOx, NHx, organic N) The good and the bad of reactive nitrogen Can N cycle be better managed? An assessment on the potential of nitrification inhibitors for better N fertilizer management

  3. Humans have more than doubled the amount of natural N fixation natural biological N fixation on land: 110 Tg N/yr in ocean: 140 Tg N/yr Fertilizer Fossil fuel Legume crop Erisman et al. 2011, Current opinion in environmental sustainability

  4. The good of anthropogenic Nr: Food Productivity Almost half of the food consumed by mankind is based on the increased production by use of nitrogen fertilizers Fritz Haber : Nobel Prize in Chemistry, 1918, - for the synthesis of ammonia from its elements Erisman et al 2008, Nature Geoscience Carl Bosch (1874-1940): Nobel Prize in Chemistry, 1931, - chemical high pressure methods

  5. Nitrogens carbon benefit NEE of non-forest natural ecosystem mean (16) grassland (7) wetland (6) tundra (3) EC of forest ecosystem mean (17) coniferous forest (8) deciduous forest (9) SOC of agriculture system mean (18) .4 .6 .8 1.0 1.2 1.4 2.5 response ratio Liu and Greaver, 2009. Ecology Letters

  6. Anthropogenic Nr stimulates vegetation growth Xia and Wan, 2008, New Phytologist 6

  7. Anthropogenic Nr input may increase soil C sequestration organic layer C DOC mineral soil C mean (53) mean (37) mean (35) Boreal forest (7) Boreal forest (10) Boreal forest (6) T. conifer forest (24) T. conifer forest (9) T. conifer forest (17) T. mixed forest (17) T. mixed forest (13) T. mixed forest (8) Tropical forest (4) Tropical forest (6) Tropical forest (5) grassland (6) 0.0 0.5 1.0 1.5 2.0 2.5 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 0.8 1.0 1.2 1.4 1.6 response ratio response ratio response ratio Liu and Greaver, 2010. Ecology Letters C 7

  8. Why ? 1.4 1.3 Response ratio 1.2 1.1 1.0 .9 .8 .7 fine roots litter input microbial respiration aboveground litter input microbial biomass carbon soil respiration C input ( ) C output (n.s.) Organic layer ( ) microbial activity Mineral soil (n.s.) Liu and Greaver, 2010. Ecology Letters

  9. Nitrogen saturation Open and leaky N cycle Closed N cycle NH3 Gruber and Galloway 2008, Nature Chapin et al. 2011, Principles of Terrestrial Ecosystem Ecology 9

  10. Increases biogenic N2O and CH4 emission CO2 CH4 N2O CO2 Photosynthesis (+) ANPP (+) N input autotrophic respiration (+) C allocation BNPP(+/-) root uptake C supply (+/-) N toxicity (+) C:N (-) C substrate supply (+/-) heterotrophic respiration (+/-) C cycle N cycle SOC DOC DIN/DON + positive feedback - negative feedback Liu and Greaver, 2009, Ecology Letters 10

  11. Nitrogens carbon benefit is largely offset by N2O an CH4 emission 1.5 53-76% 1 0.5 Pg CO2 equivalent / yr 0 -0.5 -1 -1.5 CO2 uptake CH4 emission CH4 uptake N2O emission -2 -2.5 Forest Grassland Wetland Agriculture Global Liu and Greaver, 2009, Ecology letters 11

  12. Impacts of reactive N on climate change Process altered by reactive N Climate forcer direction description N2O N2O emission warming ecological and atmospheric processes N deposition CH4 CH4 emission warming ecological processes N deposition CO2 CO2 uptake cooling ecological processes NOx ozone CO2 CO2 emission warming ecological processes NOx ozone CH4 ozone, CH4 cooling Atmospheric processes Nox aerosol sulfate, nitrate, ammonium aerosol cooling Atmospheric processes NH3 aerosol sulfate, nitrate, ammonium aerosol cooling Atmospheric processes 12

  13. Estimates of net changes in US GHG fluxes CO2, CH4 and N2O emission/ uptake factors + 13

  14. Climate change impact of US Nr emissions for 20 yrs and 100 yrs warming cooling Atmospheric & ecological processes Atmospheric processes Ecological processes 14 Pinder et al. 2012. PNAS

  15. Nrs other environmental costs Clark and Tilman 2008 Nature

  16. Could N cycle be better managed? Low nitrogen fertilizer use efficiency Tilman et al. 2002, Nature

  17. Synchronize N release to that plant growth uptake 20-50% of the applied N fertilizer Nitrification inhibitor 17

  18. The potential of nitrification inhibitors for better N fertilizer management Soil N conditions NH4 NO3- (171) SIN (146) + (191) Environmental impacts Soil N leaching + leaching (62) - leaching (16) NH4 NO3 SIN leaching (16) GHG emission CO2 emission (15) N2O emission (150) CH4 emission (25) Air pollutant emission NO emission (12) NH3 emission (62) Vegetation responses Crop productivity Grain productivity (175) Forage productivity (89) Vegetable productivity (26) Nitrogen use effeciency N concentration (60) N uptake (61) N recovery (87) Qiao et al. In preparation 0.0 0.5 1.0 1.5 2.0 2.5 Response ratio

  19. C cycle N cycle Atmosphere + increased - Decreased n.s no significant changes Photosynthesis N decomposition N NO (- 20%) NH3 (+ 11%) CH4 (n.s) CO2 (n.s) N2O (- 56%) Yield (+ 12%) N concentration (+ 10%) Denitrification N2O Litter N uptake (+ 17%) Soil N fertilizer +NI Mineralization Nitrification CO2 SOM NO3- (- 41%) NH4+ (+ 53%) AMO DIN (n.s) Immobilization CH4 NH4+ leaching (+78%) Surface and ground water NO3- leaching (- 57%) DIN leaching (- 35%) Qiao et al. In preparation

  20. Cost/benefit analysis of NI in agriculture ecosystem Response kg N/ha Monetary value $/ha Cost/benefit $/ha Variable $/kg N N2O -0.430 1.240 0.533 NH3 -2.480 -1.300 -3.224 Environmental impact 22.454 NO -0.001 23.000 0.023 DIN leaching -9.270 2.710 25.122 N fertilizer save 9.270 1.210 11.217 Fertilizer input -0.450 Nitrification inhibitor Wheat productivity - -1.167 -11.667 Crop yield 0.7 t/ha 249 $/t 174.300 174.300 Total monetary value 196.304 Qiao et al. In preparation 20

  21. Conclusion The use of Nr fertilizers makes remarkable contribution to alleviate global food shortage. The anthropogenic Nr loading also enhances ecosystem carbon sequestration The massive release of the excess N creates severe environmental problems: GHG emission, biodiversity loss, eutrophication, soil acidification NI is an applicable approach to improve N managements .

  22. Thank you! Lingli.liu@ibcas.ac.cn 010-62836160 22

  23. How many kg C can be fixed with 1kg N/ha N deposition? Critical C:N ratio Wood 200+ Leaves 20-40 Legume leaves 10 Fungi Bacteria 5-10 Surface soil 14 8-15 Magnani et al. 2007, Nature 175-225 kg C per Kg N (Magnani et al. 2008, Nature) 30-70 kg C per Kg N (de Vries et al. 2008, Nature) 65 kg C per Kg N (Thomas et al. 2010, Nature Geoscience) 24.5 kg C per Kg N (Liu and Greaver 2009, Ecology letters) 23

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