Nitrate is recognized as the most common agriculture-related contaminant of ground water. In Kansas, over 25% of rural drinking water wells exceed the 44 mg NO3L-1drinking water standard, and most of these wells are found in areas with fine textured soils. An experimental site near Manhattan, KS with a silty clay loam soil (fine, montmorillonitic, mesic Pachic Argiustoll) has received up to 224 kg N ha-1as ammonium nitrate since 1946. Nitrate concentrations were measured in soil and soil solution to determine the extent of leaching in this fine-textured soil. A crude N balance for these soils indicated that approximately 98 kg N ha-1yr-1were available for leaching from the plots receiving 224 kg N ha-1. Soil analyses in 1965 revealed much higher concentrations of nitrate than those measured on the same plots in 1985. Ceramic cup, vacuum, soil solution samplers were installed at 1.5 and 3.5 m in the 224-kg N ha-1plots to monitor nitrate movement with minimal disturbance of the plots. Nitrate concentrations in the 3.5-m samples usually reached a maximum in March and were at a minimum in August, indicating that the bulk of the fertilizer nitrate required approximately 12 months to leach to the 3.5-m depth. This projected time of leaching was supported by a simple piston-flow model and observations on a bromide tracer applied to the plots in 1989. Significant concentrations of nitrite (up to 7.38 mg L-1) were sporadically observed in the solution samples. Although the appearance and concentrations of nitrite in these samples did not follow a temporal trend, the occurrence of this potentially toxic anion near ground water is noteworthy.