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Title: Greenhouse Gas Fluxes in an Eastern Corn Belt Soil: Weather, N Source and Rotation

item Hernandez Ramirez, Guillermo
item Smith, Douglas

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2008
Publication Date: 3/25/2009
Citation: Hernandez Ramirez, G., Brouder, S.M., Smith, D.R., Van Scoyoc, G.E., Filley, T.R. 2009. Greenhouse Gas Fluxes in an Eastern Corn Belt Soil: Weather, Nitrogen Source and Rotation. Journal of Environmental Quality. 38:841-854.

Interpretive Summary: Global warming effect is a very important environmental problem, and agricultural systems may contribute to mitigate this problem. The increasing concentrations in the atmosphere of greenhouse gases such as carbon dioxide, methane, and nitrous oxide are known as responsible for global warming effect. In this study, gas samples were collected in corn and soybean fields as well as in restored prairie grass in Indiana during 40 gas sampling dates in two years. These gas samples were analyzed for all three greenhouse gases. In general, we observed that carbon dioxide emissions were not different among corn fields. Although methane emissions were in general little, soils emitted methane after the application of manure. Nitrous oxide emissions were high in corn fields with fertilizer applications in the spring. Restoration of prairie grass in cropland, soybean fields, and field with application of manure in the late fall showed beneficial impact on mitigation of nitrous oxide in this study. This research is important to growers, scientists, and policy-makers interested in management practices and cropping systems that can reduce the contribution of agricultural soils to global warming effect.

Technical Abstract: The relative contribution of diverse managed ecosystems to the greenhouse gas effect is not completely documented. This study was conducted to estimate soil surface fluxes of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and global warming potential (GWP) as affected by management practices and weather. Gas fluxes were measured by vented, static chambers in Drummer and Raub soil series during two growing seasons evaluating corn cropped continuously (CC) or in rotation with soybean (CS), and fertilized with urea-ammonium nitrate (UAN), or with liquid swine manure applied in either the spring (SM) or fall (FM). Soybean (SC) in rotation with CS and restored prairie grass (PG) were also included. The CO2 fluxes were correlated with soil temperature (rho 0.74***) and accumulated rainfall 120 hours prior to sampling (rho 0.53***), and N2O fluxes with soil temperature (rho 0.34***). Seasonal CO2 emissions and GWP were typically not different across treatments (4.4 and 5.2 Mg CO2-C ha-1 yr-1, respectively), but differed between the years. Soil receiving manure CCSM and CCFM were net seasonal CH4 emitters, whereas CSUAN and CCUAN recorded CH4 uptake (0.329, 0.159, -0.128, and -0.177 kg CH4-C ha-1 yr-1, respectively). Seasonal N2O emissions showed highly significant (P < 0.001) treatment differences (CCSM: 8.17a, CCUAN: 6.40ab, CSUAN: 4.89bc, CCFM: 3.29cd, SC: 0.98de, and PG: 0.24e kg N2O-N ha-1 yr-1) and they were mainly driven by pulse emissions after N fertilizer inputs in concurrence with major rainfall events. The results suggest that fall manure application, corn-soybean rotation, and restoration of prairie grass may diminish N2O emissions and hence might contribute to GWP mitigation.