Impact of a Turfgrass System on Nutrient Loadings to Surface Water¹

Turfgrass systems are one of the most intensively managed land uses in the United States. Establishment and maintenance of high quality turfgrass usually implies substantial inputs of water, nutrients, and pesticides. The focus of this work was to quantify the concentration and loading of a typically maintained municipal turfgrass environment on surface water. Water quantity and quality data were collected from a golf course in Austin, Texas, and analyzed for a 13‐month period from March 20, 1998, to April 30, 1999. Twenty‐two precipitation events totaling 722 mm, produced an estimated 98 mm of runoff. Nutrient analysis of surface runoff exiting the course exhibited a statistically significant (p < 0.05) increase in median nitrate plus nitrite nitrogen (NO 3 +NO 2 ‐N) concentration compared to runoff entering the course, a statistically significant decrease in ammonia nitrogen (NH 4 ‐N), but no difference in orthophosphate (PO 4 ‐P). During the 13‐month period, storm runoff contributed an estimated 2.3 kg/ha of NO 3 +NO 2 ‐N and 0.33 kg/ha of PO 4 ‐P to the stream. Storm flow accounted for the attenuation of 0.12 kg/ha of NH 4 ‐N. Baseflow nutrient analysis showed a statistically significant increase in median NO 3 +NO 2 ‐N, a significant reduction in NH 4 ‐N, and no change in PO 4 ‐P. Estimated NO 3 +NO 2 ‐N mass in the baseflow was calculated as 4.7 kg/ha. PO 4 ‐P losses were estimated at 0.06 kg/ha, while 0.8 kg/ha of NH 4 ‐N were attenuated in baseflow over the study period. Even though nutrient concentrations exiting the system rarely exceeded nutrient screening levels, this turfgrass environment did contribute increased NO 3 +NO 2 ‐N and PO 4 ‐P loads to the stream. This emphasizes the need for parallel studies where management intensity, soil, and climate differ from this study and for golf course managers to utilize an integrated management program to protect water quality while maintaining healthy turfgrass systems.