In what may be the only model of its kind in the country, southern Willamette Valley farmers are working closely with state and federal agencies to monitor innovative farming practices that may improve groundwater quality.
“This is a voluntary effort on the part of area farmers to evaluate agricultural management practices – especially fertilizer and irrigation – and how they impact groundwater,” said Audrey Eldridge, a hydrogeologist with the Oregon Department of Environmental Quality, and the coordinator of the Southern Willamette Valley Groundwater Management Area.
The primary thrust of this unique partnership was the installation and monitoring of lysimeters in 13 active agricultural fields and two privately owned control fields by the Environmental Protection Agency with partial funding provided by the Oregon Department of Agriculture’s Fertilizer Grant. A lysimeter is a device installed below the root level of crops, which then collects water that passes through the root zone. These water samples are analyzed by DEQ’s Hillsboro laboratory to document the amount of fertilizer that is “leaving” the field, and thus the amount of nitrate that is not consumed by plants. In some cases, the lysimeters measured nitrate levels that are six times the drinking water standard. While low levels of nitrate may not significantly impact groundwater quality; higher levels (greater than 7.0 mg/L Nitrate) over large fields can critically affect the health of the groundwater system.