Regional Approaches to Climate Change (REACCH) in the Inland Pacific Northwest: Eddy Covariance Flux Measurements for High and Low Rainfall Wheat Cropping Systems.

It is becoming increasingly important to investigate the relationship between global climate and agriculture in the face of ongoing climate change and the need to feed a growing global population.  The REgional Approaches to Climate CHange (REACCH) USDA-NIFA project is focused on Inland Pacific Northwest cereal cropping systems with an overarching goal to develop strategies for regional agriculture to mitigate and adapt to climate change.  An important component of REACCH is to establish a baseline of greenhouse gas (GHG) fluxes for current and alternate management practices.  We report here initial eddy covariance measurements of GHG fluxes for three sites:  one in a high rainfall, annual cropping system under no-tillage management, one in the same region but under conventional tillage management, and the third in a low rainfall, grain-fallow rotation with conventional tillage management.  The measurements were collected from three-meter eddy covariance towers. Each tower is equipped with a sonic anemometer, open-path infrared gas analyzer, and peripheral meteorological instruments. In addition, a system to measure nitrous oxide (N₂O) with a closed-path instrument was deployed periodically at the sites to capture hot moments of N₂O emissions. The flux data are analyzed for patterns associated with management events and meteorological conditions including seasonal differences and cross-site variability.  The eddy covariance data are also compared to enclosure chamber measurements collected at the high rainfall site.