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The contribution of maize cropping in the Midwest USA to global warming: A regional estimate

Grace, Peter, Robertson, G, Millar, Neville, Colunga-Garcia, Manuel, Basso, Bruno, Gage, Stuart, & Hoben, John (2011) The contribution of maize cropping in the Midwest USA to global warming: A regional estimate. Agricultural Systems, 104(3), pp. 292-296.

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Abstract

Agricultural soils emit about 50% of the global flux of N2O attributable to human influence, mostly in response to nitrogen fertilizer use. Recent evidence that the relationship between N2O fluxes and N-fertilizer additions to cereal maize are non-linear provides an opportunity to estimate regional N2O fluxes based on estimates of N application rates rather than as a simple percentage of N inputs as used by the Intergovernmental Panel on Climate Change (IPCC). We combined a simple empirical model of N2O production with the SOCRATES soil carbon dynamics model to estimate N2O and other sources of Global Warming Potential (GWP) from cereal maize across 19,000 cropland polygons in the North Central Region (NCR) of the US over the period 1964–2005. Results indicate that the loading of greenhouse gases to the atmosphere from cereal maize production in the NCR was 1.7 Gt CO2e, with an average 268 t CO2e produced per tonne of grain. From 1970 until 2005, GHG emissions per unit product declined on average by 2.8 t CO2e ha−1 annum−1, coinciding with a stabilisation in N application rate and consistent increases in grain yield from the mid-1970’s. Nitrous oxide production from N fertilizer inputs represented 59% of these emissions, soil C decline (0–30 cm) represented 11% of total emissions, with the remaining 30% (517 Mt) from the combustion of fuel associated with farm operations. Of the 126 Mt of N fertilizer applied to cereal maize from 1964 to 2005, we estimate that 2.2 Mt N was emitted as N2O when using a non-linear response model, equivalent to 1.75% of the applied N.

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ID Code: 43037
Item Type: Journal Article
Keywords: Global Warming Potential, Nitrous oxide, Maize
DOI: 10.1016/j.agsy.2010.09.001
ISSN: 0308-521X
Subjects: Australian and New Zealand Standard Research Classification > AGRICULTURAL AND VETERINARY SCIENCES (070000) > AGRICULTURE LAND AND FARM MANAGEMENT (070100)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Institutes > Institute for Sustainable Resources
Deposited On: 13 Jul 2011 23:09
Last Modified: 03 Dec 2012 12:06

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