A collaborative Washington State University study of how nitrogen and water availability vary within the Palouse wheat fields is promising to help producers manage nitrogen fertilizer better, and help reduce a greenhouse, nitrous oxide.
U.S. Department of Agriculture's National Institute of Food and Agriculture awarded $4.6 million, a five-year grant, through its Agriculture and Food Research Initiative to conduct the study with researchers from WSU, the University of Idaho and the USDA Agricultural Research Service.
The probe will be conducted at WSU's Cook Agronomy Farm research facility near Pullman, Wash., with additional testing at eight farms in the Palouse.
Ag is primarily responsible for human-induced nitrous oxide emissions into the atmosphere, claims David Brown, associate WSU crop and sciences professor, and director of the project.
Atmospheric concentrations nitrous oxide, just one of four considered to be "greenhouse" gases, have consistently risen for decades, mostly due to the increased use of synthetic nitrogen fertilizers since World War II, says Brown.
Yet, these fertilizers have also played a critical role in cereal yield increases over this period, and reducing their application uniformly could have serious consequences for crop production.
Site-specific information on water, soil and crops must also be factored in to precisely manage N applications within fields, Brown says.
Major project components include:
Landscape analysis 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 factor of crop density, water availability, temperature and soil properties.
"The strategy is to apply nitrogen more efficiently," says Brown. "Apply it only when it's needed, as much as needed, and no more. In the end, we have a much better chance of producing the real tools for farmers to improve nitrogen-use efficiently, optimize profits, and reduce nitrous oxide emissions."
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.
The region also has a mean annual precipitation ranging from 200-700 millimeters over just 100 miles in Whitman and Latah counties.
"We mimic the Great Plains but in a much shorter geographic area," notes Brown. "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."