Research You Can Use

Buffer Strips, Runoff, and LeachateResearch compares nutrient loading in runoff and leachatewhen buffer strips are used alongside golf course fairways.

BY JOHN C. STIER AND WAYNE R. KUSSOW

especially noxiousweeds, must be regularlycontrolled. Lastly, prairieplantings are not neces-sarily suited for manyhabitats, such as woodedgolf courses. A numberof golf courses utilizefine fescues as low-maintenance roughs,which receive almost aslittle attention as prairieareas, yet establishquickly and easily.Generic regulations thatrequire the installationof prairie buffer stripscan be costly, reducevaluable golf turf areas,and promote theassumption that turf

has inherently negative environmentalconsequences.

Data from various projects suggestthat annual nutrient loading frommowed turf may be similar to thatfrom prairies, as most of the nutrientloss occurs when nutrients are leachedfrom dead foliage. When we began thestudy in 2003, there were no data thatdirectly compared the efficiency ofturf to prairie vegetation for its abilityto minimize runoff and leachate pollu-tion, particularly during the establish-ment phase, which can last for two tothree years.

The project goal was to compare therelative amount of nutrient loading inrunoff and leachate when prairie andfine fescues were used as buffer strips

facilitates human activity while dis-couraging vermin and insect pests.The various turf species allow sometype of turf to be established across adiversity of situations, including moistor dry soils, and moderately shaded tofull-sun conditions.

Prairie plantings are being increas-ingly promoted as a low-cost alterna-tive to managed turf They are alsoseen as "native," while most cool-season turf species were introducedfrom Eurasia. Although managementis usually much less intensive than turf,establishment of prairie vegetation isnot necessarily less expensive than turf,as prairie seed may cost considerablymore. Prairie establishment may takeyears, during which time weeds,

~-~ -1 ~The slower establishment of prairie vegetation aI/owed annual weeds and grasses todominate in the research buffer strip plots.

ederal mandates todecrease nutrientpollution of water

supplies are resulting invarious local and stateregulations aimed atreducing phosphorus(P) movement intosurface waters andnitrogen movementinto groundwater.Some regulations aimto reduce nutrient andsediment loading intosurface waters based onthe idea that "native"or prairie vegetationshould be used asbuffer strips betweenmowed turf and naturalareas or surface water.

Some research indicates that denseturf vegetation is more effective atreducing runoff and nutrient leachingthan other strategies, including mulchedlandscaped beds. Data are just startingto be published that report on theeffectiveness of prairie buffer strips toreduce nutrient loading in water run-off and leachate relative to turf Alsounknown is the size requirement ofbuffer strips relative to the area theyare to be buffering.

Turf is often used as a ground coverthroughout inhabited areas, includinggolf course roughs, because it is rela-tively easy to establish and maintain,provides contiguous ground coverthroughout the year under traffic andmowing, and the low mowing height

16 GREEN SECTION RECORD

Table 1 Vegetative buffer strip treatments at Wisconsin River Golf Cli

Vegetation Type Ratio

No buffer, fairway only (annual bluegrass) Not applicable

Fairway: prairie (narrow buffer strip)

Fairway: fine fescue (narrow buffer strip)

Fairway: prairie (medium buffer strip)

Fairway: fine fescue (medium buffer strip)

Fairway: prairie (wide buffer strip)

Fairway: fine fescue (wide buffer strip)

8:1

8:1

4:1

4:1

2:1

2:1

jb, Stevens Point, Wis .

Mean Area (m2)

12.45

14.01

14.01

15.58

15.58

18.68

18.68

alongside golf course fairways. We also wanted to determine the effect of three different ratios of buffer strips relative to the fairway area draining into the buffer strips. The information will be useful for predicting effective­ness of different vegetation types and buffer strip sizes on golf courses.

GROWING BUFFER STRIPS AND INSTALLING WATER SAMPLERS Research plots were constructed in 2003 at the Wisconsin River Golf Club (WRGC) in Stevens Point, Wis. The golf course is adjacent to and drains into the Wisconsin River. Two large natural areas exist within the course and the course is surrounded primarily by forest with a small amount of agricultural land. The plots were developed in the roughs that drain fairways 4, 8, and 9. Fairways were approximately 85 feet wide and crowned in the middle with 1-2% slopes. Fairway turf was predominantly annual bluegrass (Poa annua L.).

Buffer strip plots were installed at the edge of the fairways and had slopes ranging from approximately 1 to 4%. Plots on fairway 9 were in full sun, plots on fairway 8 were in slight shade, while plots on fairway 4 were moder­ately shaded. Treatments included 2:1, 4:1, and 8:1 fairway-to-buffer-strip ratios, with one ratio each of prairie or fine fescue mixtures (Table 1). A seventh treatment in each replicate was a no-buffer-strip plot.

Runoff collection flumes (1-meter width) were installed at the lower end

of each buffer strip plot. Each collec­tion flume had a cover to prevent debris from falling into the flume, while a screen-covered slit at the soil surface allowed runoff water to enter. Leachate was collected in each buffer strip, using a low-tension lysimeter

installed just upslope of the runofF-collection weir.

Plots were dormant-seeded in October, as recommended for prairie plantings, and they were covered with a biodegradable wood fiber erosion control blanket. Prairie plots "were planted to a commercial prairie seed mixture that included flowers and grasses (Table 2). Fine fescue plots were seeded to a commercial seed mix containing Chewings, creeping red, blue, and hard fescues.

None of the plots "were irrigated, treated with pesticide, or fertilized during the study. Plots "were mowed (clippings returned) at 30-inch height in early spring 2004 and 2005 to encourage new growth in accordance

Table 2 Species and cultivars used for vegetative buffer strips

at Wisconsin River Golf Club, Stevens Point, Wis .

Perennial Flowers

Species*

Asclepia incamata (Red Milkweed) Aster novae-angliae (New England Aster) Iris shrevei (Wild Iris) Liatris pycnostachya (Dense Blazingstar) Lobelia siphilitica (Great Blue Lobelia) Lobelia cardinalis (Cardinal Flower) Eupatorium purpureum (Woodland Joe Pye Weed) Monarda fistulosa (Bergamot)

Rudbeckia subtomentosa (Sweet Black-Eyed Susan) Verbena hastate (Vervain) Vernonia fasciculate (Ironweed) Zizia aurea (Divided Leaf Golden Alexander)

Blooms

Color

Pink/ Red Purple Blue

Purple Blue

Scarlet Pink

Purple

Yellow Purple

Yellow

Grasses and Sedges

Month**

6-7 8-10 5-8 8-9 8-9 7-8 7-8 7-9

7-10 7-10

5-6

Andropogon gerardi (Big Bluestem) Elymus canadensis (Canada Wild Rye) Carex vulpinoidea (Fox Sedge) Glyceria striata (Fowl Manna

Fine Fescue Mixture

Species/Cultivar

Creeping Red Fescue (SR52I0) Slender Creeping Red Fescue (Dawson) Blue Fescue (SR3210) Chewings Fescue (SR5I00) Chewings Fescue (Sandpiper) Hard Fescue (SR3150) Hard Fescue (Scaldis)

*Quantity of species varies depending upon that year's include at least 12 perennial flower species. Due to tl collection, certified seed is unavailable.

**Number corresponds to month of year, e.g., 7 = July,

Scientific Name

Festuca rubra ssp. rubra F. rubra ssp. litoralis

F. glauca F. rubra spp. commutata F. rubra spp. commutata

F. longifolia F. longifolia

Grass)

% in Mix

19.6 19.6 14.7 14.7 9.8 9.8 9.8

seed production and harvest; was supposed to e nature of prairie seed production and

8 = August, etc.

M A R C H - A P R I L 2 0 0 7 17

Establishing buffer strips around natural water features on a golf course has long been recommended to protect water quality and improve wildlife habitat.Research indicates that dense turf vegetation is effective at reducing runoff.

with recommendations for prairieestablishment. Fairways received 108to 216 lb. N acre-J annually in one ortwo applications (spring and fall), withapproximately 5.5 to 11 lb. P acre-1

each year. Fairways received little tono irrigation, so snow melt and rainfallprovided the source of runoff water.The 9th fairway remained floodedfrom excessive rainfall throughout

most of 2004 and part of 2005 and wasdropped from the study.

ANALYZING WATERQUALITY ANDVEGETATIONThe leachate water samples wereanalyzed for nitrate- and ammoniacal-N and soluble phosphorus. Runoffsamples were analyzed for three P types:

soluble P, biologically active phosphorus(BAP), and total phosphorus (TP),which were extracted from both sedi-ment in the water as well as the wateritself Sediment in runoff was collectedand quantified. Turfgrass and prairieplant stands were analyzed two tothree times each year by determiningthe percentage of desirable plants (turfor prairie), weeds, and bare soil.

Figure IType and amount of vegetative cover in fine fescue and prairie buffer strips following seeding in October 2003,

Wisconsin River Golf Club, Stevens Point, Wis. A and 0 show ground cover in fine fescue and prairie plots, respectively,in August 2004. C and 0 show ground cover in fine fescue and prairie plots, respectively, in June 2005.

A

• Fescue (93.5%)• Weeds (4%)• Soil (2.5%)

18 GREEN SECTION RECORD

B

• Weeds (80%)• Soil (20%)• Prairie (0%)

c

• Fescue (88%)• Weeds (8%)• Soil (4%)

D

• Weeds (76%)• Soil (6%)• Prairie (18%)

Table 3Monthly rainfall (mm) during runoff sampling periods

at Wisconsin River Golf Club, Stevens Point, Wis.

are not favorable are likely to result inunwanted vegetation and/or exposedsoil that will not necessarily decreasenutrients in runoff or leachate.

In our study, less than 5% of thetotal rainfall during the samplingperiod in 2004 ran off fairway andbuffer strip surfaces, while less than 1%of rainfall ran off during 2005 (Tables3 and 4). The minimal slopes of thefairways (1-2%) likely helped infiltra-tion to occur by reducing speed ofrunoff despite periods of heavy rain.

The nearly complete ground cover waslikely just as, if not more, important forreducing runoff by slowing its rate andallowing it to infiltrate into the soil.

N one of the buffer strips changedrunoff or phosphorus loading comparedto the fairway alone, indicating fertilizerwas not an important source of phos-phorus (Table 4). Total phosphoruslosses on a land area basis were similar,or less than, the annual 0.1 kg P ha-1

loss reported for native prairie inMinnesota when rainfall-induced

907.8

822.183.1

Nov TotalOct

32.3

132.8 48.330.2

Sep

188.0

Aug

2004

121.7

2005

151.9

Jul

33.3

148.8

Jun

167.1

171.7

73.9

May

222.032.3

92.5

Apr

RESULTS AND DISCUSSIONFine fescues covered nearly 40% of theground by early May 2004, while weedseedlings were the only vegetation on

_ the prairie plots. Fescue cover wasexcellent by August, while annualweeds covered 80% of the ground inprairie plantings (Figures lA, lB). Afew prairie plants were present, butthey comprised less than 1% of theground cover. By June 2005, fescuecover remained dense and prairievegetation had increased to 18%,though weeds still covered more thanthree quarters of the plot area (Figures1C, lD). Several of the prairie flowerspecies were evident by summer 2005,though few bloomed that year. Noneof the prairie grasses were ever observed,consistent with several of our otherestablishment projects using similarprairie seed mixtures. Prairie plots onfairway 4 had more weeds, especiallyPoa annua, than plots on fairway 8 thatwere less shaded. Regulations requiringnative vegetation for buffer strips insituations where climatic conditions

Table 4Total annual runoff volumes and phosphorus (P) losses from Poa annua fairways withor without various buffer strips of either prairie or fine fescue, Stevens Point, Wis.

Water Runoff Total P Bioavailable PBuffer Treatment' (mm) (kg ha") (kg ha-')

20042

No buffer 36.6 0.12 0.04Short, Prairie 42.9 0.17 0.03Short, Fescue 45.6 0.19 0.04Medium, Prairie 50.1 0.17 0.04Medium, Fescue 38.1 0.16 0.04Long, Prairie 36.6 0.12 0.03Long. Fescue 50.2 0.22 0.02Significance (P~0.05) ns ns ns

20053

No buffer 3.5 0.04 0.01Short, Prairie 4.2 0.03 0.02Short, Fescue 4.6 0.04 0.03Medium, Prairie 5.5 0.04 0.02Medium, Fescue 5.5 0.05 0.02Long, Prairie 3.5 0.03 0.02Long, Fescue 4.1 0.02 0.02Significance (P~0.05) ns ns ns

ns = not significant at P:::;O.05.'Short buffer = 8: I fairway:buffer length. medium = 4: I fairway:buffer, long = 2: I fairway:buffer.2May through October.3 April through November.

MARCH-APRIL 2007 19

ns = not significant at P~0.05.'Short buffer = 8: I fairway:buffer length. medium = 4: I fairway:buffer, long = 2: I fairway: buffer.2May through October.3April through November.

Table 5Mean monthly soluble phosphorus (P) and total nitrogen (N) in leachate

under POQ QnnUQ fairway and prairie or fine fescue buffer strips,Wisconsin River Golf Club, Stevens Point, Wis.

Buffer Treatment' Soluble P (mg L.I) Total N (mg L")

20042

No buffer 0.33 2.89Short, Prairie 0.32 7.60Short, Fescue 0.12 32.08Medium, Prairie 0.24 7.05Medium, Fescue 0.05 30.15Long, Prairie 0.13 6.28Long, Fescue 0.07 25.66Significance (P::;0.05) ns ns

20053

No buffer 0.58 3.91Short, Prairie 0.56 4.15Short, Fescue 0.36 5.02Medium, Prairie 0.20 2.33Medium, Fescue 0.36 4.00Long, Prairie 0.26 3.61Long, Fescue 0.49 3.72Significance (P::;0.05) ns ns

runoff averaged 6 mm per year, andsimilar, or less, than the 0.18 to 7.04 kgP ha-1 in surface runoff from a varietyof grazing lands in Oklahoma.

Phosphorus runoff in our studywas more than 20 times less thanthat reported for wheat production,probably due to greater vegetativecover in the golf course system. Phos-phorus sources in our study likelyincluded natural sources such as vege-tation, soil, and precipitation. We'vefound similar results when comparingKentucky bluegrass (Paa pratensis) andprairie buffer strips for controllingurban runoff

A growing body of evidenceindicates that when ground is wellcovered by vegetation (e.g., 70%), totalP losses may be much reduced com-pared to predominantly exposed soil.In exposed soil situations, sediment-bound P is often the primary type ofP. Vegetation greatly reduces total Prunoff by reducing both runoff volume

20 G R E ENS E C T ION R E COR D

and sediment, though soluble P mayincrease as it leaches from vegetationand organic P-containing particlesmove in runoff Prairie plants may beespecially prone to P loss from vege-tation, as they are predominantly C4

plants with foliage that dies in earlyautumn, while C3 turf foliage maysurvive the winter and has a steady butlow turnover rate coupled with lessabundant above-ground biomass thanprairie vegetation.

In our study, about 25-50% of thetotal P in runoff was bio-available P(BAP). This is the type that stimulatesalgae blooms in ponds, lakes, andrivers. Values in our study were at least20 times less than BAP in wheat fieldrunoff and similar to BAP runoff fromnative grassland. Our data are impor-tant because they represent naturalbackground levels of phosphorus.Consequently, regulations to limitphosphorus fertilization would in thiscase be ineffective at reducing phos-

phorus loading. Ultimately it is impos-sible to achieve zero P runoff

Buffer strips did not affect phos-phorus or nitrogen leaching below thesoil surface (Table 5). Nitrogen is themost important nutrient contaminantin leachate water because excessivelevels in drinking water may haveadverse human health effects, such asblue baby syndrome. The U.S. Envi-ronmental Protection Agency sets thedrinking water limit at 10 parts permillion (ppm) nitrate-nitrogen. In ourstudy, this level was exceeded in 2004under the fine fescue plots, but theresults were not statistically differentfrom leachate under prairie plots orfairway alone. The higher concentra-tions in 2004 were likely due to soildisturbance effects from the establish-ment process and lack of vegetativecover until May 2004. In 2005, allnitrogen concentrations were below 10ppm and were likely lower than 2004because more vegetation existed in thesecond year.

Phosphorus has generally beenregarded as having little movement insoil and so most leaching studies donot measure phosphorus. However,increasing awareness of ties betweenground and surface water may soonrequire additional knowledge of phos-phorus leaching. Easton and Petrovicreported more than 50% ofP appliedto turf from swine compost leachedbelow the surface, while synthetic fer-tilizer sources had significantly lowerleachate losses. Our study indicatesthat an unfertilized prairie stand hassimilar levels of P leachate comparedto unfertilized fine fescue turf andfertilized P. annua fairways. Phosphorusand nitrogen contamination of runoffand leachate water from golf coursefairways was similiar to natural back-ground levels reported for non-fertilized native prairies and was notaffected by buffer strip type or size.

Acknowledgements: The authors wishto express their appreciation for fundingprovided by the USGA's Turfgrass and

A Q&A with DR. JOHN STIER, University of Wisconsin,regarding the use of prairie versus fescue buffer striPs tominimize nutrient and sediment fairway runoff.

Q: Your article points to recent regulations that bufferstrips, to reduce nutrient and sediment loading into surfacewaters, should use native, or prairie, vegetation. How doyou think regulators chose to stiPulate prairie vegetation forthis purpose? Is there scientific data to show that a prairiestrategy is effective for this purpose?A: Regulators chose prairie vegetation for use asnative buffer strips because much of the southern partof Wisconsin was largely prairie (e.g., oak savannah)before the 1800s. The other alternative is trees, whichbecause of their height and relatively slow growth areillogical to meet immediate needs, even though thenorthern half of the state is naturally forested. Wedecided to investigate the utility of prairie buffer stripsto control runoff specifically because no previousscientific data existed.

Q: Given the differences in speed of establishment offescues (and other turfgrasses) versus prairie ground cover,do you think that using prairie vegetation for fairway bufferstrips is a sound strategy?A: While prairie ecosystems can take several years tobecome established, we found that the annual weedsthat developed in the prairie plots functioned as wellas fescues to mitigate runoff and sediment loss. Thequestion is, will people accept weeds as a vegetativecover during the years required to establish a prairieecosystem? We also noticed that in one of the sites,heavily shaded by trees, the prairie plants did notestablish as well as the site with more sunshine.

Q: In your study, less than 5% (in 2004) and 1% (in 2005)of the total rainfall ran off the fairway and buffer stripsurfaces. Do you think the differences in sediment andnutrient losses between prairie and fescue buffers wouldhave been greater if the plots had been tested on a golfcourse receiving greater rainfall or having more severeslopes?A: The differences might have been greater if slopeswere more severe. As for rainfall, factors to considerinclude pre-existing soil moisture at the time of rainfall

and rate of rainfall compared to i~filtration rate. Forexample, if the soil is saturated from previous rainfalls,even a minor rainfall might cause runoff, while a moresevere rainfall may not cause any runoff if the soil is dryat the time of rainfall.

Q: It was interesting that your research showed thatapplied fertilizer did not appear to be an important sourceof runoff phosphorus. Do you think the extent that signifi-cant phosphorus runoff comes from dead or dormant vege-tation (i.e.,C4 prairieplants) is well understood by regulators?A: Unfortunately, the idea that vegetation itself canserve as a source of nutrients does not appear to bewell understood by regulators or the general public -it would be interesting to survey scientists to deter-mine their understanding of vegetation as a source ofnutrients in runoff. The idea is not completely new, asseveral studies have shown that nutrients can beleached from tree leaves.

Q: Your study demonstrated that bio-available phosphorusrunoff from WRGC fairways was 20 times less than thatreported for wheat production. Do you sometimes get thefeeling that regulators target golf courses rather than con-ventional agriculture, where the cumulative runoff fromrow-crop, small grain, forage production, and pasture andfeed-lot operations seem to be a much greater threat tosurface water quality?A: The turf and allied green industries do not seem tohave the political infrastructure that organized row-crop agriculture has. Also, most of the public is veryfamiliar with urban landscapes because the vastmajority of U.S. residents live in urban areas: they areunfamiliar with row-crop agricultural systems.

Q: What is the the take-home message for golf coursesuperintendents from this work?A: Well-vegetated areas, regardless of the species, areimportant for minimizing runoff and sediment losses.There will always be a background level of nutrients inrunoff water because the vegetation itself may serve asa source of nutrients in addition to atmosphericdeposition and other sources unrelated to fertilizer.

JEFF Nus, PH.D., manager, Green Section Research.

Environmental Research Program andthe Northern Great Lakes Golf CourseSuperintendents Association, and co-operation from the owners and super-intendent of Wisconsin River GolfClub.

Editor's Note: A more completeversion of this report can be found atUSGA Turfgrass and EnvironmentalResearch Online:http://usgatero.msu.edu/v05/n22.pd£

JOHN C. STIER, PH.D., is associateprofessor} Environmental TU1jgrassScience}Horticulture Dept.} and WAYNE R.Kussow, PH.D., is professor emeritus}turfgrass soil scientist} Soil Sciences Dept.}University of Wisconsin} Madison} Wis.

MARCH-APRIL 2007 21