From field to groundwater: Quantifying crop nitrogen budgets, performance metrics, and nitrate leaching in the southern Willamette Valley, OR

This presentation will cover recent research on nutrient inputs, agricultural management and nitrate concentrations in soil solution and groundwater in the southern Willamette Basin’s Groundwater Management Area.  The primary topics for this presentation will be an analysis of the trends in well water nitrate concentrations from 2006-2018 in the GWMA area, using data from the Oregon Department of Environmental Quality's water sampling program.  The primary finding is that despite a fair amount of attention and effort related to reducing groundwater nitrate contamination, well nitrate concentrations have increased since about 2012.  EPA will also present the results of a RARE project completed at the end of FY21 that measured nitrate leaching from production farmland in order to understand how on the ground practices influence nitrate leaching.   This presentation will allow us to communicate with EPA agricultural advisers and others about the findings, explanations, implications and application for our study results.  

Impact/Purpose

Nitrate contamination of groundwater is an important issue in many agricultural areas across the country. Nutrient best management practices are needed in these areas to allow for sustainability of agriculture and water quality. Researchers from EPA, Oregon Department of Environmental Quality, Oregon Department of Agriculture, local Soil and Water Conservation Districts, and USDA-NRCS study nutrient management in production agriculture in one of Oregon's Groundwater Management Areas (GWMA), established due to high nitrate concentrations in drinking water sources. This research examines nitrate leaching in production farm fields, collaboratively with local farmers, to understand the actual rates of nitrate leaching from production farming. This team uses the data on N leaching, fertilizer application and yield to develop a set of benchmarks that can be used to better understand agricultural N management. These metrics, combining information on nitrate leaching with yield, crop N output and other metrics, can provide the farm community and local organizations a way to compare agricultural and environmental performance of fields and crop types in the southern Willamette Valley GWMA.

Citation

Compton, J., J. Renee Brooks, A. Henning, S. Pearlstein, R. Coulombe, L. Erban, B. Hatteberg, C. Piscitelli, J. Selker, AND J. Weitzman. From field to groundwater: Quantifying crop nitrogen budgets, performance metrics, and nitrate leaching in the southern Willamette Valley, OR. EPA Agricultural Issues Forum Monthly Call, NA, N/A, August 26, 2021.