Nitrogen and Phosphorus Concentrations in Surface Waters of Three Delaware Golf Courses.
Amy L. Sprinkle1, G.D. Binford1, D.J. Hansen1, and T.E. McKenna2. (1) University of Delaware, 152 Townsend Hall, Newark, DE 19716, (2) Delaware Geological Survey, 223 Delaware Geological Survey, Newark, DE 19716
Concerns over losses of nutrients from land to nearby water supplies are an issue throughout the world. This issue is especially important in Delaware due to elevated nutrient concentrations in nearby estuaries such as the Chesapeake Bay and the Delaware Inland Bays. In Delaware, all individuals that apply nutrients to more than four hectares must be nutrient management certified and must develop and follow nutrient management plans. During the certification process, it became apparent that the public perceives golf courses as a significant source of nutrient loading to surface waters. Because of this perception, several golf course superintendents desired an evaluation of the impact of their current nutrient management practices on water quality. Therefore, in 2003, we began monitoring the nitrate, ammonium, and phosphorus (P) concentrations in surface waters at several locations on three golf courses in Delaware. Water samples were collected biweekly from March through September and monthly from November through February. Sampling for this study began in March of 2003 and ended in October of 2004. Water samples were collected in 125 ml high-density polyethylene bottles that were rinsed in the sample water three times before sampling at mid-stream, or mid-depth approximately 10 cm below the water surface. Samples were immediately placed in a cooler with ice for transport to the laboratory where they were immediately filtered and submitted to the University of Delaware Soil Testing Laboratory to be analyzed for ammonium, nitrate, and dissolved P. Nitrate and ammonium were measured using a Technicon Auto Analyzer. Dissolved P was determined using inductively coupled plasma (ICP) atomic emission spectroscopy. Nutrient concentrations varied spatially and temporally at the three golf courses, although ammonium concentrations were always negligible. At golf course 1, the concentration of nitrate in the surface water as it entered the course was often significantly greater than the concentration of nitrate in the surface water as it exited the course. At golf courses 2 and 3, there was little difference in nitrate concentrations between the water entering and exiting the courses. Golf course 2 had one sampling site on the course that was always quite high in nitrate concentrations but these high concentrations did not seem to be a result of current management practices. Phosphorus concentrations were always quite low at golf courses 2 and 3, while golf course 1 had one site out of ten (a pond) that tended to have elevated concentrations of P. Overall, the results of this water monitoring project suggest that all three golf courses are using effective best management practices with their current nutrient management programs and that these practices are not contributing significant quantities of either nitrogen or phosphorus to surface waters.