Phosphorus concentration and loading reductions following changes in fertilizer application and formulation on managed turf.

Excess phosphorus, particularly in surface waters can lead to severe eutrophication. Identifying source areas, quantifying contributions, and evaluating management practices are required to address current and future water quality concerns. A before-after study was conducted from 2003-2010 on a sub-watershed of Northland Country Club Golf Course in Duluth, MN to demonstrate the impacts of two different phosphorus management approaches (Period 1: traditional application and timing using commercially available synthetic blends; Period 2: reduced rate, low dose applications, and organic formulations). Outflow median dissolved reactive phosphorus (DRP) and total phosphorus (TP) stream concentrations were significantly less in Period 2 compared to Period 1. There was no statistical difference in the mean TP loading in Period 1 (0.25 kg ha(-1) year(-1)) compared to Period 2 (0.20 kg ha(-1) year(-1)) or between the DRP loading in Period 1 (0.15 kg ha(-1) year(-1)) compared to Period 2 (0.09 kg ha(-1) year(-1)). However, by switching to organic phosphorus formulations and reducing application rates by greater than 75%, substantial reduction in DRP and TP concentrations was achieved. Based on these findings it is recommended that turf managers (parks and recreation to golf courses) explore the feasibility of altering their fertility management related to phosphorus by including organic formulations, low dose applications, and overall rate reductions. Additionally, it is recommended that the fertilizer industry develop and make more readily available commercial blends with lesser to zero amounts of phosphorus.

Stream water nutrient enrichment in a mixed-use watershed.

Eutrophic conditions, in both saline and freshwater systems, result from nutrient export from upstream watersheds. The objective of this study was to quantify the surface runoff losses of nitrate-nitrogen (NO3-N), total nitrogen (TN), dissolved reactive phosphorus (DRP), and total phosphorus (TP) resulting from prevailing practices on a managed golf course. Inflow and outflow discharge waters on a sub-area of Northland Country Club (NCC) located in Duluth, Minnesota were measured for both quantity and quality from April through November from 2003 to 2008. Nutrient losses were detectable throughout the year, had a seasonal trend, and routinely exceeded recommended levels to minimize eutrophication. The median outflow TN concentration (1.04 mg L⁻¹) was significantly greater (p < 0.05) than the median inflow (0.81 mg L⁻¹) concentration. Similarly, the median outflow TP concentration (0.03 mg L⁻¹) was significantly greater (p < 0.05) than the median inflow concentration (0.02 mg L⁻¹). Maximum recorded concentrations during the study period were 1.9 mg L⁻¹ NO3-N, 3.93 mg L⁻¹ TN, 0.34 mg L⁻¹ DRP, and 1.11 mg L⁻¹ TP. Mean annual export coefficients at NCC were 0.7 kg ha⁻¹ NO3-N (1.7% of applied), 4.43 kg ha⁻¹ TN (10.7% of applied), 0.14 kg ha⁻¹ DRP (2.6% of applied), and 0.25 kg ha⁻¹ TP (4.6% of applied). The findings of this study highlight the need for adopting conservation practices aimed at reducing offsite nutrient transport.

Chlorothalonil and 2,4-D losses in surface water discharge from a managed turf watershed.

Managed turf sites (golf courses) are the most intensively managed landscapes in the urban environment. Yet, long-term watershed scale studies documenting the environmental transport of agrichemicals applied to these systems are rare. The objective of this study was to quantify the surface discharge losses of two commonly applied pesticides (chlorothalonil and 2,4-D) resulting from prevailing practices on a managed golf course. Inflow and outflow discharge waters on a subarea of Northland Country Club located in Duluth, MN were measured for both quantity and quality from April through November from 2003 to 2008. The median chlorothalonil outflow concentration (0.58 microg L(-1)) was significantly greater (p < 0.05) than the inflow concentration, which was below the detection limit (0.07 microg L(-1)). Similarly, the median outflow 2,4-D concentration (0.85 microg L(-1)) was significantly greater (p < 0.05) than the inflow concentration (0.31 microg L(-1)). Chlorothalonil concentrations occasionally exceeded acute toxicity levels (7.6 microg L(-1)) reported for rainbow trout. No 2,4-D concentrations exceeded any human or aquatic species published toxicity level; however, the maximum measured 2,4-D concentration (67.1 microg L(-1)), which rarely occurred, did approach the 70 microg L(-1) maximum contaminant level (MCL) for that compound. Losses of both pesticides were detectable throughout the annual sampling period. Mean annual chlorothalonil loading was 10.5 g ha(-1) or 0.3% of applied, while mean annual 2,4-D loading was 4.9 g ha(-1) or 0.5% of applied. The findings of this study provide quantifiable evidence of agrichemical transport resulting from typical turfgrass management and highlight the need for implementation of best management practices to combat the offsite transport of agrichemicals used in professional turf management.

Nutrient load generated by storm event runoff from a golf course watershed.

Turf, including home lawns, roadsides, golf courses, parks, etc., is often the most intensively managed land use in the urban landscape. Substantial inputs of fertilizers and water to maintain turf systems have led to a perception that turf systems are a major contributor to nonpoint source water pollution. The primary objective of this study was to quantify nutrient (NO(3)-N, NH(4)-N, and PO(4)-P) transport in storm-generated surface runoff from a golf course. Storm event samples were collected for 5 yr (1 Apr. 1998-31 Mar. 2003) from the Morris Williams Municipal Golf Course in Austin, TX. Inflow and outflow samples were collected from a stream that transected the golf course. One hundred fifteen runoff-producing precipitation events were measured. Median NO(3)-N and PO(4)-P concentrations at the outflow location were significantly (p < 0.05) greater than like concentrations measured at the inflow location; however, median outflow NH(4)-N concentration was significantly less than the median inflow concentration. Storm water runoff transported 1.2 kg NO(3)-N ha(-1) yr(-1), 0.23 kg NH(4)-N ha(-1) yr(-1), and 0.51 kg PO(4)-P ha(-1) yr(-1) from the course. These amounts represent approximately 3.3% of applied N and 6.2% of applied P over the contributing area for the same period. NO(3)-N transport in storm water runoff from this course does not pose a substantial environmental risk; however, the median PO(4)-P concentration exiting the course exceeded the USEPA recommendation of 0.1 mg L(-1) for streams not discharging into lakes. The PO(4)-P load measured in this study was comparable to soluble P rates measured from agricultural lands. The findings of this study emphasize the need to balance golf course fertility management with environmental risks, especially with respect to phosphorus.

Nutrient flux in storm water runoff and baseflow from managed turf.

The urban landscape is comprised of many land uses, none more intensively managed than turfgrass; however, quantification of nutrient losses from specific land uses within urban watersheds, specifically golf courses is limited. Nitrate (NO(3)-N) and dissolved reactive phosphorus (DRP) were measured on a golf course in Austin, TX, USA from April 1, 1998 to March 31, 2003. NO(3)-N and DRP concentrations measured in storm flow were significantly greater exiting the course compared to those entering the course. Significant differences were also measured in baseflow NO(3)-N concentrations. The measured loading from the course was 4.0kg NO(3)-Nha(-1)yr(-1) (11% of applied) and 0.66kg DRPha(-1)yr(-1) (8% of applied). The resulting concentrations contributed by the course were 1.2mgL(-1) NO(3)-N and 0.2mgL(-1) DRP. At these levels, NO(3)-N poses minimal environmental risk. However, the DRP concentration is twice the recommended level to guard against eutrophication.