Keith E. Schilling and Matthew T. Streeter, University of Iowa, Iowa City, IA
Nonpoint source pollution from nitrate-nitrogen (N) and phosphorus (P) contributes to nutrient enrichment in local streams and lakes and development of hypoxic zones in regional water bodies. Although the Iowa Nutrient Reduction Strategy (INRS) was developed to reduce N and P delivered to Iowa rivers from point and nonpoint sources, it did not address contributions from golf courses. The purpose of this reconnaissance study was to measure N and P concentrations in surface and groundwater at a subset of Iowa golf courses to assess the risk posed by these facilities to contribute N and P loads to Iowa rivers. Six golf courses were randomly selected for this study and included three 18-hole courses and three 9-hole courses in eastern, central and western regions of Iowa. Monitoring wells were installed within managed turf grass areas at each course in representative tees, fairway and rough locations. Results generated from the project in year 1 indicate that N and P concentrations in soil and shallow groundwater are low at most courses. Nitrate concentrations in groundwater ranged from <1 to 27 mg l-1 and were <1 mg/l at four of the six courses. Total P concentrations ranged from 0.02 to 0.31 mg l-1 and averaged approximately 0.1 mg l-1 at all six courses. We are currently working with the course superintendents to compile land management practices including timing, rate and formulation of fertilizer applications, which will be used to relate soil and groundwater nutrient concentrations to golf course practices.