Citation:

Lin, J., J. Compton, S. Bittman, C. Clark, P. Homann, D. Hooper, D. Schwede, B. Carey, H. Winter, P. Kiffney, N. Embertson, G. Boggs, R. Black, R. Sheibley, G. Bahr, AND J. Baron. ‘A tale of two regions': Nitrogen inventories in the Nooksack-Fraser Transboundary Watershed. American Geophysical Union, Washington, DC, December 10 - 14, 2018.

Impact/Purpose:

The Nooksack-Fraser Transboundary Nitrogen (NFT-N) project is a team of federal, state and local scientists, managers and community groups working together to inform sustainable fisheries and agriculture in the region. The NFT-N team created a nitrogen (N) budget for the watershed spanning the border of U.S. and Canada. The transboundary watershed has prolonged coastal eutrophication and contaminated groundwater issues due to excessive N. Livestock feed and fertilizer import were the two largest sources, accounting for 63% and 15% of total N input to the U.S. part of the watershed, respectively. Food import for human and pet together accounted for 11% of total N input; deposition contributed 10% of N input to the watershed. About 25% of dairy manure N was lost as ammonia, and 8% via denitrification. Only 47% of manure N was directly available for plant uptake. Careful management of agricultural fertilizers and manures is key to improving water quality. Results will be refined by integrating with an existing Canadian N budget to achieve a complete budget, and applied to build an ecosystem model to simulate N outcome under various management scenarios.

Description:

Spanning the border of U.S. and Canada, the Nooksack-Fraser transboundary area (2639 km2) is home to the communities of Lynden, Washington, and Abbotsford, British Columbia, with a strong base in farming, fisheries and outdoor recreation. Balancing these uses is a key issue in the area, where nitrogen (N) loading contributes to coastal eutrophication and prolonged contamination of groundwater. The Nooksack-Fraser Transboundary Nitrogen (NFT-N) project had an initial goal of creating a N budget using data on energy use, transportation, fertilization, wastewater treatment, livestock operations, and fisheries. Using local data, we estimated that livestock feed and fertilizer import were the two largest N input sources to the U.S. part of the watershed, averaging 3472 and 1131 metric tons (MT) N yr-1, respectively. Atmospheric deposition was the third largest source of N to the watershed, averaging 527 MT N yr-1. The import of human and pet food added 655 MT N per year to the watershed. The returns of adult salmon brought in 6 MT N yr-1 to the watershed. N loss through volatilization of manure averaged 2035 MT N yr-1, and denitrification losses were approximately 204 MT N yr-1. N fluxes in surface and ground water will be estimated using load simulation and mass balance approaches. Preliminary results for the U.S. side demonstrate the importance of N inputs from agriculture sector, indicating that careful management of agricultural fertilizers and manures is key to improving water quality. Results will be refined by integrating with an existing Canadian N budget to achieve a complete budget for the watershed, and used to understand connections between inputs and N fates in ground and surface water. The budget will be used as a foundation to develop an ecosystem model for management scenario simulation, using the Visualizing Ecosystem Land Management Assessments (VELMA) model tool to support future efforts in developing sustainable N management plans in the region.

Record Details: