USE OF CHLORIDE AND FLUORESCENT DYE AS TRACERS IN MEASURING NITRATE AND ATRAZINE TRANSPORT THROUGH SOIL-PROFILE UNDER LABORATORY CONDITIONS

Laboratory experiments were conducted using undisturbed soil columns ( one From no-tillage and one from moldboard plow fields) to monitor the performance of adsorbed and nonadsorbed tracers in predicting nitrate and atrazine movement through the soil profile and to the shallow gro undwater systems. Chloride (Cl) and Rhodamine WT dye were used as surr ogate tracers for nitrate-nitrogen (NO3-N) and atrazine oro-4-ethylami no-6-isopropylamino-1,3,5-triazine), respectively. The chemical soluti on containing 0.005 M calcium nitrate, 0.005 M calcium chloride, 83 pp b atrazine, and 1 ppm Rhodamine was used for developing breakthrough c urves to observe chemical leaching through saturated soil columns. Sim ilarity between the NO3-N and CI breakthrough curves suggested that Cl ion can successfully be used as a tracer for observing NO3N transport through soil columns. Significant difference between the Rhodamine WT and atrazine breakthrough curves indicated that use of Rhodamine WT i s not an ideal tracer for monitoring atrazine transport through soils. Breakthrough curves for nitrate and chloride were similar under bath tillage systems but atrazine breakthrough cur;es showed a greater degr ee of preferential movement through no-tillage soil column.