Spatially explicit estimates of N2 O emissions from croplands suggest climate mitigation opportunities from improved fertilizer management

James S. Gerber, Kimberly M. Carlson, David Makowski, Nathaniel D. Mueller, Iñaki Garcia de Cortazar-Atauri, Petr Havlík, Mario Herrero, Marie Launay, Christine S. O'Connell, Pete Smith, Paul C. West

Research output: Contribution to journalArticlepeer-review

121 Scopus citations

Abstract

With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2O emissions at the country scale by aggregating all crops, under the assumption that N2O emissions are linearly related to N application. However, field studies and meta-analyses indicate a nonlinear relationship, in which N2O emissions are relatively greater at higher N application rates. Here, we apply a super-linear emissions response model to crop-specific, spatially explicit synthetic N fertilizer and manure N inputs to provide subnational accounting of global N2O emissions from croplands. We estimate 0.66 Tg of N2O-N direct global emissions circa 2000, with 50% of emissions concentrated in 13% of harvested area. Compared to estimates from the IPCC Tier 1 linear model, our updated N2O emissions range from 20% to 40% lower throughout sub-Saharan Africa and Eastern Europe, to >120% greater in some Western European countries. At low N application rates, the weak nonlinear response of N2O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2O emissions. As aggregated fertilizer data generate underestimation bias in nonlinear models, high-resolution N application data are critical to support accurate N2O emissions estimates.

Original languageEnglish (US)
Pages (from-to)3383-3394
Number of pages12
JournalGlobal change biology
Volume22
Issue number10
DOIs
StatePublished - Oct 1 2016

Bibliographical note

Publisher Copyright:
© 2016 John Wiley & Sons Ltd

Keywords

  • NO
  • climate change
  • emissions
  • flooded rice
  • greenhouse gas
  • manure
  • meta-analysis
  • nitrogen
  • nitrous oxide
  • sustainable agriculture

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