The Impact of Soil Type and Precipitation onPesticide and Nutrient Leaching from Fairway Turfby DR. A. MARTIN PETROVICCornell University

Soil Pesticide Climatic

Site Texture Leaching Name Leaching Rainfall/Irrigation

Fairway Sand High Isazofos High Above normalSandy loam Intermediate Mecoprop High NormalSilt loam Nominal Triadimefon Intermediate

Trichlorfon High

Table 2Pesticides and Fertilizers Applied in Fairway and Green Study

Common Trade Rate* of Date ofName Name Formulation Application Application

FairwaysIsazofos Triumph 4E 1.5 oz/lOOOsq ft Aug. 25, 1992Mecoprop Mecomec Potassium salt 1.5 oz/lOOOsq ft Sept. 24, 1991Trichlorfon Proxol 80SP 3.75 oz/lOO sq ft July 2,1992Triadimefon Bayleton 25WP 2 oz/lOOOsq ft Sept. 24, 1991

4 oz/lOOOsq ft Oct. 11, 1991Fertilizer Scotts 29-3-7 lIb N/lOOOsq ft Sept. 1991

Oct. 1991June 1992Sept. 1992Oct. 1992

GreensTriadimefon Bayleton 25WP 4 oz/lOOOsq ft Oct. 25, 1992

*Forpesticides,rates are the amount of product applied

Table 1Factors Evaluated in Golf Course Environmental

Research Project, Cornell University

High Triadimefon Intermediate NormalIntermediate

for leaching. Climatic factors, like theamount of rainfall and/or irrigation, that alsoinfluence pesticide leaching were alsoevaluated in this project. Table 1 summarizesall the factors studied.

Experimental ConditionsThese experiments were conducted in the

field to simulate actual golf course condi-tions, but without the golfers. The sites were

SandSand/peat(80/20)

Green

affect pesticide leaching. For example, thesoils used ranged in texture from sand, witha high potential for pesticide leaching, to asilt loam soil, which has a nominal potentialfor pesticide leaching. The pesticides usedalso reflect a range in potential for leaching,with mecoprop (MCPP), trichlorfon(Proxol), and isazofos (Triumph) having ahigh potential for leaching, and triadimefon(Bayleton) having an intermediate potential

THREE YEARS AGO, in a projectfunded by the United States GolfAssociation, a team of researchers

from Penn State University, the University ofMassachusetts, and Cornell University setout to establish a more comprehensiveknowledge base as to the fate of pesticidesand fertilizers applied to experimental fair-ways in large-scale field research facilities.The three universities divided the researchobjectives based upon the specialized facili-ties at each site. The same pesticide andfertilizer materials were used at each site togive the project cohesiveness. Penn StateUniversity investigated the extent of pesti-cide and nutrient runoff from fairway-typeturf consisting of either creeping bentgrass orperennial ryegrass. The University of Massa-chusetts examined volatilization and foliardislodgeability of pesticides applied to fair-way-type turf (creeping bentgrass). CornellUniversity studied the impact of soil type andprecipitation on pesticide and nutrientleaching from fairway-type turf (creepingbentgrass). The results of the Penn StateUniversity and University of Massachusettsstudies are found elsewhere in this issue.

The objectives of Cornell University'sportion of this project were to determinepesticide and nutrient leaching from high-maintenance fairway-type turf as influencedby:

• Soil texture (sand, sandy loam, and siltloam)

• Pesticide properties (persistence andmobility)

• Rainfall differences (moderate and veryheavy rainfall patterns)

• Turfgrass maturity (density and organicmatter accumulation)

A second objective of this project wasto determine the impact of the addition oforganic matter (peat) at the time of construc-tion on pesticide leaching from experimental,sand-based putting greens.

During the summer of 1993 we experi-enced major lightning storm damage to ourmain research facility, so as of this date notall of the objectives of this research projecthave been met.

This study was designed to examine awide range of conditions that are known to

38 USGAGREEN SECTION RECORD

mowed frequently and were fertilized/irri-gated at rates typically used on golf courses.

Fairway StudiesFairways comprise the largest area of the

more highly maintained portion of golfcourses. Fairways therefore are where thelargest quantity of pesticides and fertilizersare used on a high-quality golf course. Fair-ways usually are built with on-site soils thatcan range from very sandy soils to very fme-textured clays. It is known that the extent ofeither pesticide or nutrient leaching is highlydependent on soil properties. Thus, it isimportant to study nutrient/pesticide leach-ing from fairway areas representing severalsoil types.

This research was conducted at theARESTS (Automated Rainfall ExclusionSystem for Turfgrass Studies) Facility at theCornell University Turfgrass Field ResearchLaboratory in Ithaca, NY. This facility isdesigned to control all water going onto theturf (rainfall and/or irrigation) and collect allthe water passing through the soil (leachate).During the months of May through October,a large cover on wheels (called a rainoutshelter) quickly covers the experimental siteif rain occurs. This allows us to control theamount of rainfall and irrigation during thegrowing season. In this study we usedhistoric weather data and applied irrigationwater that reaches the plots to mimic anormal rainfall pattern and an above-normalrainfall pattern. In this way we could deter-mine if certain kinds of weather-type yearsare likely to result in greater pesticide/nutrient leaching than others.

The ARESTS Facility is composed of 27free-draining lysimeters (plots) that are 12 ftx 12 ft, each containing nine 15"-deep plotsdivided into three soil types (sand, sandyloam, and silt loam). Each plot is individuallyirrigated. The site was seeded with Penncrosscreeping bentgrass in May of 1991.All of thesystems are linked with a data acquisition!control system via computer. The site wascompleted in 1987 but reseeded with Penn-cross creeping bentgrass in May of 1991.Thesite was mowed three times per week (clip-pings removed) and irrigated so that at least1" of rainfall/irrigation was applied perweek.

Pesticides and fertilizer were applied toall but one plot of each soil type, whichserved as the untreated control treatment. Thematerials, rates, and dates of applicationsare shown in Table 2.

Putting Green StudyHighly sandy sites, such as putting greens,

are often cited as being the most susceptibleto nutrient and pesticide leaching due to highpermeability, low organic carbon content,and low cation exchange capacity (CEC).

During construction, the opportunity existsto modify sand with amendments thatpossibly will reduce both nutrient and pesti-cide leaching by increasing the amount oforganic carbon and the CEC level. Thus, theobjective of this section of the project was todetermine the effect of an organic amend-ment (peat) on the leaching of pesticidesfrom sand-based experimental puttinggreens. The site for this study is the CornellUniversity Turfgrass Field Research Labora-tory, Ithaca, NY. The site was constructedduring 1992 and sodded with washed creep-ing bentgrass on October 5-6, 1992. Plotsconsisted of 8 ft diameter USGA puttinggreen profiles containing 12" of root zonemix, a 2" layer of coarse sand, and 4" ofgravel at the bottom. Each plot was con-structed using a small swimming pool that

includes one outlet to collect the leachate.Reed sedge peat amendment was added tothe slightly calcarious sand at a ratio of 80:20sand to peat (v/v). Unamended sand wasincluded as a treatment for comparison.Triadimefon was applied during the week ofOctober 25, 1992.

For both studies there were four replicateplots of each treatment, and averages areshown in the accompanying tables.

Research FindingsThe nature of these studies is such that we

collected leachate samples from a depth of15'; which is considered the most importantzone for retaining and degrading pesticides/nutrients. Under real-life conditions, thiswater must move deeper through the soiluntil it reaches the water table. Therefore, the

JANUARYIFEBRUARY 1995 39

*Numberin ( ) equals the number of samplesabovethe 10 mg/L drinkingwater standardfornitratenitrogen.Only 2 of the 1385 samplesanalyzedthus far were above 10 mg/L.

Table 3The Percentage of Applied Pesticide Leached and Maximum Concentration

of Pesticide Found in the Drainage Water from Experimental Fairways

Pesticide

Soil Precipitation Isazofos MCPP Trichlorfon Triadimefon

% of Applied Pesticide Leached /Maximum Concentration

Sand Normal 10.4 51.00 1.18 1.00767* 1900 140 190

Above normal 5.6 62.12 3.44 2.44544 1400 467 118

Sandy loam Normal 0.04 0.79 1.13 0.0615 21 118 8

Above normal 0.09 0.46 4.41 0.01122 70 302 5

Silt loam Normal 0.68 0.44 0.63 0.2477 130 71 43

Above normal 0.30 1.25 3.33 0.2834 89 504 66

*Maximumconcentrationof pesticidedetectedin the drainagewater (leachate),in ug/L (ppb)

Table 4The Maximum Concentration of Nitrate and Phosphate Detectedin the Drainage Water (Leachate) from Experimental Fairways

Sampling PeriodSept. 13 - Dec. 31,1991 Jan.-Aug. 10, 1992

- - - Maximum Concentration, mg/L - - -12.2(1)* 0.17 4.3 0.1913.2(1)* 0.15 4.8 0.17<0.5 0.06 0.5 0.113.5 0.08 3.6 0.113.1 0.11 3.5 0.091.7 0.54 0.5 0.114.3 0.11 6.6 0.115.9 0.11 5.8 0.12<0.5 0.32 1.1 0.27

PhosphateNitratePhosphate

lowest of the four pesticides. Little or noleaching was observed on the two fmer-textured soils, and some leaching occurredfrom the sand experimental fairways thatwere only four months old.

The data are not shown due to the factthat triadimefon leaching from experimentalgreens was negligible. It is important topoint out that these greens were sodded witha dense, washed creeping bentgrass sod twoweeks before the pesticide was applied. Thisdense turf effectively eliminated pesticide

NitratePrecipitationSoil

Sand NormalAbove normal

UntreatedSandy loam Normal

Above normalUntreated

Silt loam NormalAbove normal

Untreated

ing into groundwater. Our results confIrmedthat isazofos does leach from sand, but thegood news is that very little leaching wasobserved in the fIner-textured soils (sandyloam and silt loam).

Pesticide properties are very importantin understanding the potential for pesticideleaching. Triadimefon (Bayleton) is con-sidered to have the lowest potential forleaching of the four pesticides used in thesestudies. For each soil, by precipitation treat-ments, the leaching of triadimefon was the

data presented here are not groundwaterquality data, but are estimates of the maxi-mum concentration of pesticide/nutrient thatcould reach groundwater, assuming a watertable depth of 15'~On sites with deeper watertables, concentrations would be less.

PesticidesItwas not surprising that pesticides leach-

ing from experimental fairways were influ-enced by soil type, the characteristics of theindividual pesticide, and the amount of pre-cipitation/irrigation, as shown in Tables 3 and4. This type of experiment is considered aworst case scenario: using highly mobilepesticides over a shallow water table onhighly leachable soil (sand) and having arainfall/irrigation pattern likely to causeleaching. However, the extent of the leachingwas quite surprisingly high in these unusualcases. For example, 50% to 62% of theapplied mecoprop (MCPP) leached from thenewly established sand experimental fairwayplot. This suggests that newly seeded turf, orother turf stands with very low shoot density,that is grown on very sandy soil is susceptibleto pesticide leaching, assuming other factorsimportant to pesticide leaching are present.Results from other research studies and frommonitoring studies of actual golf courseshave found mecoprop does not leach to anygreat extent.

We also observed in one case that leach-ing of the pesticide trichlorfon (Proxol) wasunaffected by soil type. This is highlyunusual for studies of this nature. However,with some understanding of the nature of thispart of the study, the results can be explained.First, a highly water-soluble pesticide thatdoes not easily bind to organic matter wasapplied, and a large amount of rainfall wasreceived within the fIrst eight days afterapplication (4.4" and 9.6" for the normal andabove-normal precipitation treatments, re-spectively). Highly water-soluble pesticidesthat do not easily bind onto organic mattercan move through the soil via water if theyare not quickly degraded. The extreme rain-fall that occurred within the fIrst eight daysafter application resulted in a large amountof pesticide leaching, primarily due to awater flow process known as preferentialflow. In this case, water very rapidly movesthrough soil either in macropores (wormholes, cracks in soil, etc.) in non-sand soils(i.e., sandy loam and silt loam) or in otherpreferential pathways. The data from thisstudy strongly confIrms that preferentialwater flow did occur on these soils, causedby the heavy rainfall, and that pesticideleaching was heavily influenced by thispreferential water flow.

The label for the pesticide isazofos(Triumph) states not to apply this materialon sandy areas due to a potential for leach-

40 USGA GREEN SECTION RECORD

reflected in density and organic matteraccumulation (4-month-old turf vs. 3-year-old turf) on the leaching of mecoprop fromexperimental fairways. It is our belief thatthe leaching of mecoprop will be substan-tially eliminated on turf that has matured.

Petrovic, A. M., R. G. Young, C. A. Sanchirico,and D. 1. Lisk. 1993. Downward Migration ofTrichlOlfon Insecticide in Twfgrass Soils. Chemo-sphere 27: 1273-1277.

Publications from This Project:

Petrovic, A. M., R. G. Young, C. A. Sanchirico,and D. J. Lisk. 1991. Migration of IsazofosNematocide in Irrigated Twfgrass Soils. Chemo-sphere 28:721-724.

Petrovic, A. M., R. G. Young, C. A. Sanchirico,and D. J. Lisk. 1994. Triadimenol in TwfgrassLysimeter Leachate After Fall Application ofTriadimefon and Overwatering. Chemosphere28:(in press).

Petrovic, A. M. 1993.Leaching: Current Status ofResearch. J. Intern. Turfgrass Res. Soc. 1.

Petrovic, A. M., R. G. Young, 1. G. Ebel, andD: 1. Lisk. 1993. Conversion of TriadimefonFungicide to Triadimenol During LeachingThrough Twfgrass Soils. Chemosphere 26: 1549-1557.

Petrovic, A. M., W. H. Gutenmann, 1. G. Ebel, andD.1. Lisk. 1993.Leaching of Mecoprop HerbicideThrough Twfgrass Soils. Chemosphere 26:1541-1547.

• Nitrate and phosphorus leaching fromexperimental fairways was found to beminimal.

Now for the bad news:• Turfed sites that are not dense can be

prone to substantial pesticide leaching,assuming other conditions for leaching arepresent (e.g., mobile pesticide applied andwater moving through soils).

• Preferential water flow greatly increasesthe potential for pesticide leaching.

These findings point to several things thatgolf course superintendents can do to reducethe potential for groundwater contaminationvia pesticide leaching:

• Know the sites on your golf course thathave a high probability for leaching (sandy,low-organic-matter soils, shallow watertable, thin turf, or newly seeded sites, andlikelihood of excessive irrigation due to aninadequate irrigation system).

• Determine which pesticides are morelikely to leach, and use them with cautionon sites more prone to leaching. Informationon pesticide properties is readily available,but is not listed on the pesticide label.

• Understand the conditions that areimportant in preferential water flow (periodof heavy rainfall and excessive irrigation)and avoid the use of pesticides that are proneto leaching during these periods.

Experiments are underway to determinethe effect of turfgrass stand maturity as

Each lysimeter has an individual collection port to sampleand monitor the water moving through the different soil types.

leaching (all of the leachate samples werebelow the detection limit of 5 J1g/L),regard-less of the root zone composition (sand vs.sand/peat). These data support the notion thatdense turfed sites, even on straight sand, arenot likely to be prone to pesticide leaching.

Summary

As would be expected fromany experiment that examinessuch a wide range of importantfactors that can affect pesticide/nutrient leaching, there is goodand bad news. First the goodnews:

• Pesticide leaching fromexperimental fairways wasfound to be predictable andonly occurs under the worstcase scenarios. Thus, when-ever possible, avoid applyingpesticides under worst casescenarios.

• Dense, healthy turfdramatically reduces the risk ofpesticide leaching, even onsites with the significantpotential for leaching (sand-based putting greens).

Nitrate and Phosphorus

Nitrate leaching into groundwater fromgolf courses and agricultural land treatedwith fertilizers is a concern because nitratewas found to be the major contaminant ofgroundwater in the United States in a recentU.S. Environmental Protection Agencygroundwater quality survey of private andpublic drinking wells. Phosphorus leachingfrom golf courses could be a concern if thedrainage water from the golf course endedup in surface waters like ponds, lakes, andstreams where eutrophication threatens waterquality.

The accepted drinking water standard fornitrate-nitrogen is 10 mglL. Only 2 of the1,385 leachate samples from the experi-mental fairways analyzed to date were abovethis standard. Most were way below thestandard « 1 mg nitrate-NIL). Therefore,nitrate leaching from moderately fertilizedfairway turf, even from sand, is not signifi-cant.

Phosphorus levels in the leachate from theexperimental fairways were seldom abovethe analytical detection limit of0.05 mg/L. None of the fer-tilized sites had any leachatesamples with concentrationsgreater than 0.3 mglL, whichoften characterizes the phos-phorus concentration of eutro-phic surface waters.