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 20-40% lower throughout Sub-Saharan Africa and Eastern Europe, to >120% greater in some Western European countries. At low N application rates, the weak non-linear response of N2O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2O emissions. Since aggregated fertilizer data generate underestimation bias in nonlinear models, high-resolution N application data are critical to support accurate N2O emissions estimates.
Original language | English |
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Pages (from-to) | 3383-3394 |
Number of pages | 12 |
Journal | Global Change Biology |
Volume | 22 |
Issue number | 10 |
Early online date | 4 Jul 2016 |
DOIs | |
Publication status | Published - Oct 2016 |
Keywords
- nitrogen
- climate change
- nitrous oxide
- sustainable agriculture
- greenhouse gas
- global
- meta-analysis
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Pete Smith
- Biological Sciences, Aberdeen Centre For Environmental Sustainability - Chair in Plant & Soil Science
Person: Academic