We conducted a sequential tracer leaching study on a field plot to investigate the temporal behavior of preferential flow to a field tile during an irrigation and subsequent rainfall events over a 14-d period. Two herbicides, along with the conservative tracer Br, were applied to a strip adjacent to a tile drain immediately before a 4.2-mm hr-1 irrigation. Three additional conservative fluoridated benzoates (PF, TF, and PF) were applied to the strip at 2-hr intervals during the irrigation. Breakthrough of the conservative tracer Br and the two herbicides occurred within the first 2-hr of irrigation, indicating that a small fraction of the solute moved through preferential flow paths. The last tracer (PF), applied 6 hr after the start of irrigation, took only 15 min and 1 mm of irrigation water to travel the 1.2-m distance between the soil surface and the tile. Thus, flow along preferential flow paths was faster during later stages of the irrigation. This study demonstrates that solute transport rates in preferential flow pathways is not a constant during a leaching event.