One of the consequences of climate change is the alteration of rainfall patterns. Longer dry periods and intense rainfall events have been observed in the US Midwest, an important agricultural region. Research from the summer of 2015 showed Nitrous Oxide (N2O) fluxes increased with these more extreme precipitation patterns. Therein lays a problem because N2O is a greenhouse gas that has a radiative forcing almost 300 times stronger than carbon dioxide. This then must be studied to understand the repercussions the weather patterns could have especially with the nitrogen (N) fertilizers applied to agricultural soils. N becomes N2O mainly through the incompletion of denitrification. This occurrence in the process of denitrification is often correlated with moisture, among other conditions. Knowing that moisture is influenced by landscape positions, the objective of our experiment was to see how N2O emissions are affected by changing rainfall patterns at different topographical positions. Rainfall manipulation shelters were placed at summits and depressions in corn fields. The soil in the shelters was wetted at 3 day, 14 day or 28 day intervals. Added precipitation amount was based on the thirty-year precipitation average. We measured gas fluxes using stainless steel chambers with a Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) N2O analyzer. We also used soil moisture sensors and collected soil samples to analyze their texture, labile carbon and nitrate.
Results indicated that there were cumulatively higher fluxes in depressions than summits. We also found moisture was consistently higher in those lower positions. This work will be useful to expand our understanding of how N2O emissions are affected by topography to more accurately quantify fluxes and develop mitigation practices.