Soil-applied nonionic surfactants have been shown to increase potato tuber yields in some years. It is possible that surfactants increase water infiltration into potato hills resulting in an increase in fertilizer N use and a decrease in nitrate leaching. This experiment was designed to compare three surfactants applied at planting and at plant emergence at two sites, Hancock and Grand Marsh, WI. A lower than optimum rate of N fertilizer (202 kg N ha-1) was used to help distinguish differences in N use efficiency. Surfactant sprayed at plant emergence was more effective than surfactant sprayed at planting. Tuber yields, size and N uptake were increased by surfactant application in 2003 but not in 2004, at the Hancock site however, at the Grand Marsh site data in 2004 were similar to that at Hancock in 2003. Petiole nitrate levels sampled four times did not show any treatment differences in either year. Weekly soil water samples from porous cup samplers installed at 1 m below the potato hills had somewhat lower nitrate concentrations where the surfactant was applied at emergence compared to surfactant applied at planting or the control in both years. To date, data from this experiment suggest that surfactant use can improve fertilizer N use efficiency in some years and that timing of application may offer even more benefits.