Climate change disturbs natural cycles in ecosystems throughout the planet. Increasing temperatures and changing rainfall patterns impact agriculture by decreasing crop yields, while increasing plant disease, and soil degradation. Greenhouse gas emissions cause climate change. In the United States, the predominant greenhouse gas emitted is carbon dioxide (CO2). However, since the Industrial Revolution emissions of other gases that have greater Global Warming Potential than CO2 have increased. Nitrous oxide (N2O) has 298 times the radiative forcing of CO2. Managed ecosystems like agricultural fields are the main anthropogenic N2O source.
Anaerobic conditions are favorable for denitrification, the process in which N2O emission occurs. Denitrifying organisms perform the reduction of nitrate in a sequence of steps, catalyzed by different enzymes. Previous studies have shown that the changes in rainfall patterns influence the time enzymes take to become active. This results in slowing the denitrification enzyme induction, which allows greater N2O production. This research tests how different rainfall patterns associated with climate change affecting the nitrous oxide reductase (NOS) enzyme induction during denitrification. Rainfall manipulation shelters were used to create soils exposed to same amount of rainfall delivered at different intervals (2, 7, 14 and 28 days) in plots of corn vs switchgrass.
Results/Conclusions
Preliminary results from summer 2017 samples show that NOS activity was higher in corn plots with 7 days of rainfall intervals. In switchgrass, the enzyme seems to be less effective converting N2O to N2. The greater amount of nitrous oxide reductase activity in the 7 days rainfall intervals, in corn plots, suggest that the enzyme lag could be influenced by nitrate leaching due to excess or lack in the amount of water received in the other rainfall treatments. Results from summer 2018 will also be reported. Understanding the patterns of NOS activity in different rainfall intervals is important to determine N2O fluxes in agricultural fields and develop mitigation practices.