Fate and Management of Turfgrass Chemicals - ACS Publications

Chapter 5

Potential Movement of Nutrients and Pesticides following Application to Golf Courses L . M. Shuman, A . E . Smith, and D. C . Bridges

Downloaded by CORNELL UNIV on August 18, 2016 | http://pubs.acs.org Publication Date: December 29, 1999 | doi: 10.1021/bk-2000-0743.ch005

Department of Crop and Soil Sciences, University of Georgia, Griffin, G A 30223

Bermudagrass plots (3.7 m x 7.4 m) were established with a 5% slope to measure water runoff and associated nutrients and pesticides. Treatments included were dimethyl-amine (DMA) dicamba, D M A mecoprop, D M A and 2,4-D, chlorothalonil, dithiopyr, chlorpyrifos, benefin, and pendimethalin. Fraction of applied analytes transported from the plots ranged from 0.01% for benefin and pendimethalin to 14% for dicamba and mecoprop. The relationship between fraction transported and the negative log of the analyte solubility in water (pSw) was better fitted by a quadratic (R , 0.96) than a linear function (R , 0.86). For 1997 accompanying lysimeter leachate data for two working USGA golf greens showed that fertilizer NO -N required 20 to 30 days to appear in the leachate and PO -P required 30 to 50 days depending on fertilizer source and rainfall. 2

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Watersheds delineate areas of interacting land and water resources and provide logical ecosystem boundaries. Relationships between landscape patterns and ecological processes are of particular relevance to the management of urban watersheds influenced by nonpoint source pollutants. Some of the most dramatic changes in landscape patterns in the U.S. are those associated with rapid urbanization. From 1980-1992 the U.S. population increased by 19.4%, to 255 million. Nearly 15% of that increase occurred in metropolitan areas. Expansion of metropolitan areas has spawned ever-increasing areas of turfgrass that is more intensively managed than ever before. There are over 14,000 golf courses in the U.S. and the number is increasing at the rate of one per day. Of the 700,000 ha of golf course area in the U.S. about 2% is in greens. These are typically 80% by volume coarse sand, to give a high percolation and water-removal rate. The porous medium of golf course greens coupled with high inputs of fertilizer and irrigation water promotes leaching - not only of soluble nitrogen sources, but even

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Clark and Kenna; Fate and Management of Turfgrass Chemicals ACS Symposium Series; American Chemical Society: Washington, DC, 1999.


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of less soluble phosphate fertilizer. Sandy soils often have a deficiency of mineral elements (metal oxides and secondary clay minerals) that constitute the most common adsorbing surfaces for phosphate. Even the peat that is added to the sand of a typical golf green "mix"to increase water-holding capacity and give other desirable effects as a rooting medium, can supply soluble carbon species which can exacerbate phosphate losses through complexation and decreased adsorption. The fairway areas present different problems that lead to detrimental environmental effects through fertilizer losses. In the Piedmont region of the Southeast, the soils are often impervious causing high rates of runoff during heavy rainfalls, especially on sloped areas. As much as 70% of the rain can be lost as runoff. This can cause fertilizer losses through "floatoff ' of recently applied particles and runoff of soluble species. Homeowner lawns are yet another large source of fertilizer elements being lost to surface waters. Residential and commercial lawn area is much greater in total than golf courses, and homeowners and commercial property managers are more prone to overwater and overfertilize. Nitrogen and Ρ added to turfgrasses if lost in runoff and subsurface flow can eventually find their way to potable water supplies. Added nutrients, especially P, can cause eutrophication of surface water, leading to problems with its use for fisheries, recreation, industry, or drinking water due to increases in the growth of undesirable algae and aquatic weeds (26). Phosphorus is usually the most limiting element for algae growth, since many blue-green algae are able to utilize atmospheric N as an alternative source of N . Most Ρ lost from grassed areas is also in the soluble, rather than particulate, form that is immediately available for algae growth (26). Thus, limiting both Ν and Ρ losses from turfgrass areas is an important environmental issue. Turfgrass is typically the most intensively managed biotic system in metropolitan landscapes. Increasing interest in the environmental effects of pesticides is, in general, a response to their increased use since the 1960s and due to advancements in technology allowing scientists to detect their presence at low concentrations. Many compounds, because of their constituents (many contain halogens or nitrogen), can be detected at sub-parts per billion levels. Concern for the impact of pesticides and nutrients on the environment is related to potential entrance into drinking water sources and their potential to adversely affect aquatic organisms and ecosystem functions. Although drinking water in rural areas primarily comes from groundwater sources, much of the drinking water in urban areas is derived from surface water sources such as reservoirs. It is estimated that as much as 95% of the drinking water for some major metropolitan areas comes from reservoirs. Contaminants are transported via runoff and on sediment. Erosion and runoff processes in relation to water quality and environmental impacts have been examined by Anderson et al. (7), Leonard (14), and Stewart et al. (32). Results of research conducted in the Piedmont Region of the southeastern United States has suggested that as much as 40-70% of the water from an average rainfall event on a turfgrass sod having a high water content (field capacity) and an average slope of 5% could leave the landscape as runoff water 2


80 (29). This suggests that there is a high probability for pesticides to be transported in surface waters.


Literature Review Accurate estimates of pesticide usage in urban areas are difficult to obtain, because most pesticides produced for this market are available through a wide variety of outlets and may be applied by the homeowner, a pest control operator, or municipal governments. Reliable data on pesticide and fertilizer use in urban areas are limited, and estimation of pesticide loads in urban watersheds is complicated. Studies of pesticide use in urban areas suggest that large quantities of pesticides are frequently applied. For example, a study of homeowner use in three cities (Lansing, Dallas, and Philadelphia) showed that 341,000 kg of pesticides were used by suburban homeowners annually. Most pesticides were used in lawn care, with insects the main problem in Dallas, and weeds in Lansing and Philadelphia (17). In commenting on this use, the National Academy of Sciences emphasized that many pesticides used in lawn care are applied at rates as high as 5-10 kg ha' . If this survey in three cities is representative of use by American homeowners, the fact that a population of about 3 million used 341,000 kg suggests that outdoor use of pesticides around homes may involve as much as 25 million kg of pesticides annually. As noted above, nitrates, in particular can leach through sandy golf greens, since they are soluble. In fact, the main concern for nitrogen affecting natural waters from greens is through leaching, and rather than through runoff. For example, Mancino and Troll (15) found nitrate concentrations as high as 45 mg L" in leachate from a sand-peat green. Petrovic et al. (23) found nitrate to be higher in leachate from fairways than the allowable drinking water standard of 10 mg L ' . Owens et al. (22) also found nitrates above 10 mg L ' in groundwater under a grassed pasture, mainly from downward flow and not in runoff. A factor in nitrate leaching can be the source of Ν applied. Brown et al. (6) indicated that nitrate losses were in the following order according to source: ammonium nitrate>12-12-12 fertilizer>milorganite> isobutylenediurea>ureaform-aldehyde. Some studies also show little of nitrate leaching losses, especially if moderate rates are used, excessive irrigation is avoided, and nitrates are applied to mature turf as opposed to land barely covered with vegetation (18,21). Common-sense management practices exist which may limit leaching and runoff of nitrate fertilizer from golf greens and fairways. The fertilizer rates should be scheduled for light, frequent applications of a slow-release fertilizer and irrigation should be limited to turf needs (22). Brauen and Stahnke (4) reported nitrate leaching for turf plots that had immature turf. They suggested adding nitrogen often, at low rates, to minimize leaching. Likewise, Weed and Kanwar (34) found that nitrate leaching was minimized by applying Ν at rates just enough to meet crop Ν demand and 1

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at times close to the crop's peak uptake periods. Decreasing fertilizer rates during periods of slow growth and in the winter, especially when larger volumes of water are expected, may also help to limit nitrate losses from golf courses (5). Thus, management techniques have been shown to assist in lowering nitrate loses, but more information is needed, especially concerning the width of buffer zones and proper irrigation scheduling in relation to fertilizer application. Phosphorus is transported to natural waters both in soluble form and adsorbed to soil particles, including both inorganic particles and organic matter. Since there can be large losses of soil from row-cropped agricultural lands, most Ρ lost is in particulate form, but for grassed land and forests most Ρ is transported in soluble form instead (26) . Phosphorus must be added regularly at rates of at least 25 kg ha' annually for sand golf greens (5 kg ha' per month through the growing season of May to September) (9) and, although Ρ runoff is less for grass than for cropped soils (24), Ρ does build up and can become a problem due to leaching into groundwater and runoff into surface waters (25). In Australia, Ρ was found in runoff as dissolved species and not associated with sediment (2). On undisturbed soil columns from golf fairways where Ρ was leached during heavy irrigation, 35% of the added Ρ was found below the 8-inch depth (31). The Ρ that causes eutrophication of waters is that which is bioavailable. The bioavailable Ρ is comprised of soluble Ρ and a portion of the particulate P. Thus, when analyzing runoff and leachate for P, the Ρ is commonly fractionated into soluble P, particulate Ρ and, in some cases, bioavailable particulate Ρ (27) . Soil properties can affect Ρ movement. Phosphorus breakthrough data were modeled well by a four-parameter segmented exponential model, with Ρ breakthrough found to be correlated with extractable Fe and A l , extractable P, and Ρ sorption capacity (16). Kaiser and Zech (12) found that an increase in dissolved organic carbon (DOC) content of the leachate caused a decrease in the sorption of H P0 ", suggesting that H P0 * had a higher sorption affinity than DOC. Onho and Erich (19) also showed that phosphate adsorption is inhibited by DOC derived from plant materials. Desorption of Ρ can be rapid, occurring within one to four hours following a rainfall event. Thus, desorption and subsequent loss of Ρ in runoff are a threat with every major rainfall event (>2.0 cm) for soils that have been recently fertilized. Phosphorus sorption and desorption, then, is an important factor affecting the amounts of Ρ lost in runoff as well as by leaching, and determination of soil sorption/desorption characteristics likewise is important when attempting to predict Ρ losses from soils. 1


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Materials and Methods Simulated fairways and greens. Twelve plots (3.7 χ 7.4 m), separated by landscape timbers, were developed in a grid pattern with a 5% slope. The subsoil was a clay loam and the top soil was a sandy loam. A ditch was dug at the downslope end of each plot to install a trough for collecting runoff via a tipping-bucket sample collection



82 apparatus. Plots were sprigged with 'Tifway 419' Cynodon dactylon (L.) Pers. χ C. transvaalensis Burtt-Davy on May 17, 1993 and had become completely covered with sod by August 1,1993. Wobbler off-center rotary-action sprinkler heads were mounted 7.4 m apart and 3.1 m above the sod surface. When operated at 138 kPa, the system produced a simulated rainfall at an intensity of 3.3 ± 0.4 cm/hr. A n outside lysimeter facility consisted of two greens (12 χ 1.2 m) subtended with 10 round stainless steel lysimeters (55 cm diam χ 52 cm deep) designed to direct of leachate and associated pesticides/nutrients to a central collection area. Prescribed rooting mixtures (sand and sphagnum peat moss) for the greens were based on the desired percolation rate for each grass species. Proportions were selected to give percolation rates of 39 or 33 cm/hr. Rooting media consisting of sand and sphagnum peat moss mixture of 85:15 and 80:20 (v/v) (87.7:2.3 and 86.8:3.2 by mass, respectively) resulted in the respective percolation rates. Lysimeters and areas around lysimeters were filled with sized gravel (10 cm), coarse sand (7.5 cm), and rooting mix (35 cm) in ascending sequence from the bottom, simulating U S G A specifications for greens construction (33). Layers were packed into and around each lysimeter. The 85:15 mixture had a field capacity of 0.13 cmVcm , a wilting point of 0.03 cm /cm and an effective saturated conductivity of 39.6 cm/hr. The 80:20 mixture had a field capacity of 0.15 cm /cm and an effective saturated conductivity of 33.5 cm/hr. 'Penncross* Agrostis stoloniferaL. was seeded into the 85:15 rooting media on October 15,1991 and C. dactylon was sodded over the 80:20 rooting mix on March 10, 1992. At the Cherokee Town and Country Club in Atlanta, two bentgrass putting greens also were each equipped with three lysimeters (stainless steel lysimeters 38 cm χ 53 cm χ 15 cm deep were placed 18 cm beneath each green surface). Stainless steel lines were run from the drain of each to the edge of the green where leachate was to be collected. 3

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Treatments. There were 12 plots in the simulated fairway area on Cecil sandy loam grassed to 'Tifway 419' Bermudagrass. In most cases, nine plots were used, with all treated similarly as replications so that treatments differed in time rather than in space. The initial nutrient experiment involved rates of 10-10-10 fertilizer material at 0, 12.2, 24.4, and 48.8 kg ha* giving Ρ rates of 0, 5.4,10.7, and 21.5 kg ha* . Irrigation timing and amounts initially were 4 (5.0 cm), 24 (5.0 cm), 72 (2.5 cm), and 168 (2.5 cm) hr after treatment (HAT), with collections of runoff during and following each irrigation. For pesticide experiments, plots were treated as follows: benefin (as Balan E C , 180 g a.i./L, DowElanco), chlorothalonil (as Daconil 2787, 502 g a.i./L, ISK Biosciences), chlorpyrifos (as Dursban Pro, 241 g a.i./L, DowElanco), dicamba (as Banvel, 480 g a.e. amine salt/L, Sandoz), dithiopyr (as Dimension, 119.8 g a.i,/L, Rohm and Haas), 2,4-D (as Weedar 64,456 g a.e. amine salt/L, Rhone-Poulenc), mecoprop (as Chipco Turf Herbicide MCPP, 240.6 g a.e. amine salt/L, RhonePoulenc), and pendimethalin (as Prowl, 480 g a.i./L, American Cyanamid). Treatments 1

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83 were applied between 1 June and 1 November 1993 and 1994 based on meteorological forecasts that projected for at least a 72-hr period with a low probability of rainfall. Rainfall was simulated at 24,48, 96, and 192 HAT. Following simulated rainfall, normal rainfall events also were monitored until herbicides in runoff were no longer detected. Runoff was quantified, and subsamples were collected using the tippingbucket apparatus. Treatments for field lysimeters were placed on a 1.2 by 1.2 m area using a backpack sprayer and aqueous dilutions of chlorothalonil, chlorpyrifos, 2,4-D, dicamba, dithiopyr, dithiopyr-G (as Dimension G, 0.25% a.i., Rohm and Haas), and mecoprop. Dithiopyr-G was evenly distributed over a similar area. Each treatment was replicated 4 times and each experiment was repeated one or more times. An automatic trackirrigation system was developed for controlling irrigation rates and times (30). Watering nozzles traversed a horizontal track located above the sod, at a speed of 2.9 m/min. Flow rate of water was adjusted 1.82 mL/sec at 138 kPa. Daily irrigation with 0.625 cm of water plus a weekly irrigation of 2.5 cm were controlled using an automatic timer. These conditions simulated management practices and average rainfall events for golf course greens in the Piedmont region of the United States. A n automatic moving rain shelter protected the greens during actual rainstorms. There were no planned treatments at the Country Club putting greens, with the greens remaining managed as seen fit by the greenskeeper. Detailed records were kept on the amounts of nutrients and pesticides applied. Weekly leachate samples were continuously collected starting in January, 1995, and analyzed for Ν and P. Measurements and analytical procedures. Nitrate and Ρ were analyzed using a L A C H A T flow analyzer for runoff and leachate samples. Special analysis for Ρ included forms in the leachate of total, bioavailable, and particulate P. Total Ρ (TP) was measured following perchloric acid digestion of unfiltered runoff or leachate. Soluble Ρ (SP) was determined on a filtered (0.45 μιή) sample. Particulate Ρ was taken as the difference (TP-SP). Bioavailable Ρ (BAP) was determined by extracting 20 mL of an unfiltered sample with 180 mL of 0.1 M N a O H for 17 hours shaking in an endover-end shaker. The amount of Ρ in the filtered extract was taken as the B A P . The bioavailable particulate Ρ (BPP) was taken as the difference between B A P and SP (27). All Ρ measurements were by a colorimetric method (molybdate blue-ascorbic acid) using a flow analyzer (LACHAT). Dicamba, 2,4-D, and mecoprop were analyzed by procedures developed in our laboratory (75). Subsamples of 100 mL were transferred from the storage bottle into a 250 mL beaker. An internal standard (2,4,5-T) was added to the beaker and the mixed solution was acidified to a pH of 2 with 0.2A/HC1. Pesticides were extracted from the acidified solution by liquid-liquid partitioning into 200 mL diethyl ether. The diethyl ether was evaporated and analytes were esterified with triflouroethanol (TFE). Esters were quantified by gas chromatography (GC) using an electron capture detector (ECD). Detection limit for dicamba was 0.1 μg L" and for mecoprop was 0.5 Mg L 1


84 Dithiopyr was extracted by solid phase extraction and analyzed by GC-ECD according to a method developed in our laboratory (77). The detection limit for dithiopyr was 0.4 L ' . Benefin and pendimethalin were extracted from 50 mL aqueous subsamples by liquid-liquid partitioning into 150 mL dichloromethane. Dichloromethane was concentrated under vacuum to 1 mL and diluted with 1 mL toluene containing metribuzin as an internal standard. Analytes were quantified by GCE C D . Chlorothalonil and chlorpyrifos were extracted by liquid-liquid partitioning into ethyl acetate. The ethyl acetate volume was reduced under vacuum to 1 mL and hydroxy metabolites of chlorpyrifos and chlorothalonil were methylated using 1 mL diazomethane and 0.034 g silica gel. Ânalytes and metabolites then were quantified with detection limits of 1 μ% L" . 1


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Results and Discussion Simulated fairways. The first nutrient experiment involved applying rates of 10-10-10 fertilizer over time, with each treatment being replicated by the number of plots available. The first rate was 0.5 lb of Ν per 1000 sq ft., or 2.44 g Ν and 1.07 g Ρ per m . Nitrate-N in runoff was low, because the form of nitrogen added was ammonium (Figure 1), and there was given too little time to revert to other forms. Future experiments will be carried out using different forms of N . The form of Ρ reported is SP, in that the solutions were clear and TP and B A P were essentially the same as SP. Phosphorus concentration was as high as 2.7 mg L* during the first simulated rain event and decreased thereafter. Austin et al. (2) showed a similar result for flood irrigation, where the first runoff event resulted in high runoff compared to subsequent irrigations. Concentration at 168 hours did increase over that at 72 hours, but the volume of runoff was low at that time. This is the first experiment carried out for Ν and Ρ at this site and as such the data should be considered to represent preliminary results. As noted in the discussion above, nitrate concentrations in this runoff were low because the form of Ν applied was all ammonium (Table I). The 10-10-10 formulation included ammoniated phosphate, which is usually monoammonium phosphate, and ammonium sulfate. Thus, the recovery of Ν was only 0.72 % of that added, and much of this probably came from other sources including mineralized organic nitrogen. The phosphate concentration, as an average of all runoff events, was just less than 1 mg L , with the percent recovered being approximately 11%. Although losses from agricultural land usually are

Fate and Management of Turfgrass Chemicals - ACS Publications

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