Groundwater and nitrogen management in Willamette Valley mint production

Abstract

Directly below commercial mint fields, percolation in excess of 10 ppm of nitrogen as nitrate (NO3 --N), the EPA drinking water standard, occurs for much of the year (Figure 1, page 2). Concentrations rise rapidly after irrigation starts in June, indicating that this nitrogen is being pushed through by irrigation water. On average, the groundwater received 100 lb of nitrogen per acre over the 5 years of this study (Feaga and Selker, 2004).