Spatially explicit estimates of N2O emissions from croplands suggest climate mitigation opportunities from improved fertilizer management. (4th July 2016)

• Record Type: Journal Article
• Authors: Gerber, James S.; Carlson, Kimberly M.; Makowski, David; Mueller, Nathaniel D.; Garcia de Cortazar‐Atauri, Iñaki; Havlík, Petr; Herrero, Mario; Launay, Marie; O'Connell, Christine S.; Smith, Pete; West, Paul C.
• Is Part Of: Global change biology. Volume 22:Number 10(2016:Oct.)
• Page Start: 3383
• Page End: 3394
• Publication Date: 2016-07-04
• Subjects: climate change -- emissions -- flooded rice -- greenhouse gas -- manure -- meta‐analysis -- N2O -- nitrogen -- nitrous oxide -- sustainable agriculture; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.13341
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2 O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2 O emissions at the country scale by aggregating all crops, under the assumption that N2 O emissions are linearly related to N application. However, field studies and meta‐analyses indicate a nonlinear relationship, in which N2 O 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 N2 O emissions from croplands. We estimate 0.66 Tg of N2 O‐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 N2 O 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 N2 O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2 O emissions. As aggregated fertilizer data generate underestimation bias in nonlinear models, high‐resolution N application data are critical to support accurate N2 O emissions estimates.