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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #304306
Title: Modeled nitrous oxide emissions from corn fields in Iowa based on county level data

Author
item JARECKI, MAREK - Camco Clean Energy
item Hatfield, Jerry
item BARBOUR, WILEY - Camco Clean Energy

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2014
Publication Date: 3/11/2015
Citation: Jarecki, M.K., Hatfield, J.L., Barbour, W. 2015. Modeled nitrous oxide emissions from corn fields in Iowa based on county level data. Journal of Environmental Quality. 44:431-441.

Interpretive Summary: The role of agricultural systems on the magnitude of greenhouse gas emissions is not clearly understood. However, this lack of information prevents the development of accounting methods to document the potential impact of changing agronomic management practices on greenhouse gas emissions. This study was undertaken to estimate the potential nitrous oxide from Iowa by using a simulation model coupled with the weather conditions across the state. The results showed variation in the yearly emissions of nitrous oxide because of the distribution of temperature and precipitation across the state. The comparison of the amounts between measured and simulated amounts were in good agreement; however, when the results were extended to a complete year there may be underestimates of the yearly greenhouse gas emissions. Development of management practices which can reduce the annual emissions of nitrous oxide will require information of this magnitude to cover large geographical areas. This information will be of value of scientists and policy-makers to improve our understanding of the dynamics of greenhouse gas emissions.

Technical Abstract: The US Corn Belt area has the capacity to generate high nitrous oxide (N2O) emissions due to medium to high annual precipitation, medium to heavy textured soils rich in organic matter, and high nitrogen (N) application rates. The purpose of this work was to estimate field N2O emissions from cornfields in Iowa based on available meteorological, soil and crop data using the DNDC model, and to compare the DNDC outputs with available results from field experiments. All data were acquired for 2007-2011. Weather Underground Network and ISUISPAID 7.3 database were the data sources for DNDC inputs and for computing county soil parameters. The NASS five year averages for corn yield data were used to establish ex post fertilizer N input at the county level. The DNDC output suggests county wide N2O emissions in Iowa were between 2.1 -2.2 kg N2O-N ha-1y-1 in southern central, to 5 kg N2O-N ha-1y-1 in northern central and east Iowa counties. In northern districts the average direct N2O emissions amounted to 3.6, 4.8 and 4.0 kg N2O-N ha-1y-1 for west, central and east, respectively. In central districts, average N2O emissions amounted to 3.9, 4.3 and 3.8 kg N2O-N ha-1y-1 for west, central and east, respectively. For southern districts, N2O emissions were lower and amounted to 3.7, 2.4 and 3.2 kg N2O-N ha-1y-1 for west, central and east, respectively. DNDC simulations confirmed the results from field experiments, indicating that the magnitude of N2O emissions from Iowa cropland is considerably underestimated.