IPCC Emission Factor Overestimates N2O Emissions from Agricultural Ditches

Abstract

Agricultural ditches emit disproportionate amounts of nitrous oxide (N2O), but their contributions to regional or global N2O emissions remain unclear due to limited data. The Intergovernmental Panel on Climate Change (IPCC) recommends using emission factors (EFs) to estimate indirect N2O emission, but the EF for ditches (EF5g) is categorized as groundwater, which potentially introduces a significant bias. This study conducted a regional-scale campaign in the North China Plain, one of the world's most intensive agricultural regions, and calculated the EF5g values from agricultural ditches by the concentration method (N2O-N/NO3 --N). The results found that the regional-scale mean EF5g value (0.0028) was less than half of the IPCC default value (0.006), illustrating that the current IPCC methodology significantly overestimates N2O emissions from agricultural ditches. Despite the relatively small EF5g values, agricultural ditches exhibited a high mean N2O concentration (3.36 mu g L-1) and a large regional emission (1.14 +/- 0.86 Gg N2O-N yr-1), which is equal to 3.8 +/- 2.9% of direct N2O emission from the croplands in the North China Plain. Since ditches are ubiquitous in agricultural regions and are likely to expand under climate change, refining EF5g is crucial to accurately assess their contribution to global N2O budgets.

Keywords

agricultural ditch; nitrous oxide; emissionfactor (EF); indirect emission; nitrogen fertilization; nutrient; greenhouse gases

Published in

Environmental Science and Technology
2024, volume: 58, number: 45, pages: 20019-20029
Publisher: AMER CHEMICAL SOC

SLU Authors

• Peacock, Michael

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • University of Liverpool

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use

Publication identifier

• DOI: https://doi.org/10.1021/acs.est.4c05760

Permanent link to this page (URI)

https://res.slu.se/id/publ/133195