Nitrous oxide (N2O) is the dominant natural ozone-consuming substance in the stratosphere and a strong greenhouse gas with 265 times the radiative forcing of CO2. N2O is produced by soil microbes and fluxes are closely linked with soil moisture. Consequently, documented and future changing rainfall patterns due to climate change will likely influence N2O fluxes. Since the majority of anthropogenic N2O produced globally is from agricultural soils, where fluxes are controlled by numerous factors including oxygen, nitrate, and carbon availability (all of which are strongly tied to soil moisture status), it is important to understand the impact of more extreme precipitation patterns on N2O emissions. We tested the hypothesis that changing rainfall patterns strongly alter N2O fluxes in agricultural soils as modulated by cropping system and landscape position.
We used rainfall manipulation shelters to expose soils to same amount of rainfall delivered at different intervals (3-day, 7-day, 14-day, and 28-day). The initial phase of this experiment was conducted for 10-weeks in a no-till continuous-corn system in place from 2008 at the Kellogg Biological Station Long-Term Ecological Research site in Michigan.
Results/Conclusions
Results from the 2016 field season show cumulative N2O fluxes were 2 times higher when rainfall occurred in 28-day rather than sub weekly or 14-day intervals in corn systems. Results were corroborated by measurements in 2017 and related to changes in denitrifier enzyme activity. Understanding patterns and mechanisms for N2O fluxes from managed soils is important for achieving more sustainable agriculture, developing mitigation practices, and parameterizing global biogeochemical models.