Nutrient Losses Through Tile Drains from Two Potato Fields

Two tile-drained potato (Solanum tuberosum L.) fields, approximately 5 ha (12.35 ac) each, at St. Leonard d’Aston, Quebec, were instrumented to measure tile drain flow over two growing seasons (April to November). The soil type was a St. Jude sandy loam. Nitrogen (N), phosphorus (P), and potassium (K) concentrations in tile drain flow were monitored throughout the growing seasons. Nitrogen concentrations ranging from 1.70 to 40.02 mg/L were observed. Phosphorus concentrations ranged from 0.002 to 0.052 mg/L. On one field, it was found that K concentrations were always less than 10 mg/L. However, on the other field, concentrations were mostly greater than 10 mg/L. At the end of the growing season, in the final year of the project, the total amounts of N which were removed by the subsurface drainage systems of the two fields were 14 kg/ha (12.5 lb/ac) and 70 kg/ha (62.5 lb/ac).