PULLMAN, Wash. — A collaborative Washington State University study of how nitrogen and water availability vary within Palouse wheat fields will ultimately help farmers better manage nitrogen fertilizer application on their croplands and reduce one of Earth’s top four greenhouse gases, nitrous oxide.

U.S. Department of Agriculture’s National Institute of Food and Agriculture awarded a $4.6 million, five-year grant through its Agriculture and Food Research Initiative to researchers from WSU, University of Idaho and the USDA Agricultural Research Service to conduct the study.
The project will take place at the Cook Agronomy Farm outside of Pullman, with further testing at eight additional farms in the Palouse region.
Human-induced nitrous oxide
Agriculture is primarily responsible for human-induced nitrous oxide emissions into the atmosphere, said David Brown, associate professor of crop and sciences at WSU and the project’s director. Atmospheric concentrations of the gas have consistently risen for decades mostly due to the increased use of synthetic nitrogen fertilizers since World War II. Yet these fertilizers have also played a crucial role in cereal yield increases over this period, and reducing their application uniformly could have serious consequences for crop production.
Therefore, site-specific information on water, soil and crops must also be factored in to precisely manage nitrogen applications within fields, Brown said.
Major project components include:
  • Landscape analyses to generate maps of soil and crop properties as well as soil moisture dynamics
  • Modeling to simulate crop growth, organic matter decomposition, water movement, nutrient uptake and more
  • Experiments to determine yields and greenhouse gas emissions as a function of crop density, water availability, temperature and soil properties
Applying nitrogen strategically
“The strategy is to apply nitrogen more efficiently, he said. “Apply it only where it’s needed, as much as needed, and no more. In the end, we have a much better chance of producing real tools for farmers to improve nitrogen-use efficiency, optimize profits and reduce nitrous oxide emissions.”
Why the Palouse and North Idaho?
The research team chose the Palouse region of eastern Washington and northern Idaho because it has some of the hilliest cropland in the country, which contributes substantially to soil variability and water movement. In addition, the region also has a mean annual precipitation ranging from 200 to 700 millimeters over just 100 miles or two counties, Whitman and Latah.
“We mimic the Great Plains but in a much shorter geographic area, Brown said. “A 100-mile drive across the Palouse is equivalent to a 500-mile drive across the Great Plains to get the same range in precipitation.”
Other participants
Other project researchers are:
  • Claudio Stockle, Biological Systems Engineering, WSU
  • Ann-Marie Fortuna, Crop and Soil Sciences, WSU
  • Erin Brooks, Biological and Agricultural Engineering, UI
  • Jan Eitel and Lee Vierling, College of Natural Resources, UI
  • Kathleen Painter, Agricultural Economics and Rural Sociology, UI
  • David Huggins and Jeffrey Smith, USDA ARS