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TURF & MAINTENANCE CHRIS HOPE

Golf courses live and die by thequality of their greens. Makingthe crucial decision to renovatea green and the best approachto grown in or restore a greenoften results in significantand heady discussions withingreens committees and Boardsof Directors.

Traditionally, the accepted methodfor restoring or renovating a green isseeding. It is cost effective and providesthe healthy, well-rooted turf that leadingcourses demand for their greens.However, seeding a green requires amajor upset of the course, sometimestaking up to 12 months for turf to estab-lish itself and the green to be playable.Unfortunately, with today’s fast-pacedworld, financial pressures and the fact

course members and players are oftenunwilling to play on temporary greensfor extended periods of time, seeding isan indulgence few courses can afford.

Inevitably, the discussions polarizeon the need for minimal disruption and aspeedy return of the green into play. Greensthat have been restored with sod can beopened considerably sooner than seededones. However, the use of traditional,soil-based sod can lead to a whole otherset of problems down the road that oftenwipe out any time-saving advantages.

SOIL AND SAND DON’T MIXTraditional, soil-based sod is typicallygrown on a range of soils, from sandy loamto silt and clay loams. When traditionalsoil-based sod is laid down on soil similarto what the sod was grown on, it performsvery well and will quickly develop newroots into the medium upon which it islaid. The problems with soil-based sodarise when it is introduced onto sand or

sand combined with organic matter, thestandard substrata used in green con-struction. The disparity in particle sizebetween the fine soil in the turfgrass andthe larger particle sizes in the high-drainage root zone material can some-times create a suspended water table atthe sod layer that inhibits the movementof water down through the sod. A greenthat was built to be a free draining planeis now essentially a capped surface withthe soil-based sod acting as the cap. Theresulting effect is known as “layering.” Thelayers slow the flow of water throughoutthe green, significantly inhibit rootgrowth and require a program of frequentcultivation in order to keep the turfhealthy and useable.

These problems are compoundedwhen the sod is further top-dressed withthe same material as the profile beneath it,causing the formation of yet more layersof dissimilar particle sizes. Over time, ifnot addressed, the lack of drainage caused

All the

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by this layering effect can lead to anaerobicconditions beneath the surface resultingin a black or “dead” layer. Eventually, thegreen will be unsuitable for play andrequire yet another round of restorationefforts, at further cost and inconvenience.

THE SOIL-FREE ALTERNATIVEIncreasingly, soil -free or “washed” sod isbeing used by leading courses in Canadaand the United States as an alternative toseeding in order to accommodate thetimely change-out of greens and meetexacting USGA specifications for greenstandards. Prior to soil-free sod, the onlyway to establish turf on high-sand rootzones, as per USGA specifications forgreens construction, was to seed andgrow in the stand of turf, a process thattakes months.

First developed in Australia in the1970s, soil-free sod is nursery-grown turfgrass that has been processed orwashed to completely remove any traceof soil. Originally used on sports fields

and race tracks in Australia and Asia, itsuse on golf courses was a natural extensionof its benefits to applications where turfquality is paramount. The Delta PinestoneGolf Resort in Haliburton, Ontario usedsoil-free turf to completely re-sod eightgreens using washed Bentgrass andBluegrass. Because of this success, theycontinue to renovate additional greensusing soil-free sod.

“Our membership has never hadsuch good conditions,” said Harry Baker,Director of Golf & Property with theDelta Pinestone Resort. “We workedhand in hand with our supplier to replaceour greens with soil-free Bentgrass andBluegrass. Our greens are smooth, ballsdon’t bounce and our members are happy.”

SUCCESS BASED ON SCIENCESoil-free sod is ideally suited for use onsandy soils, especially greens, allowing forrapid root extension through the soil. Byremoving the soil layer from the sod, thelayering and drainage problems associated

with traditional sod are eliminated.However, what is really getting the atten-tion of turf experts and course superin-tendents is the ability of soil-free sod toroot both quickly and vigorously.Numerous scientific studies have demon-strated the enhanced rooting capabilitiesof soil-free turfgrass. Studies1 haveshown that the use of soil-free sod canresult in as much as a 260 percentincrease in root biomass underneath thesod in as little as 21 days after installation.The maximum root depth of soil-free sodwas also found to be 60 percent greaterthan that of traditional sod. The rapidroot growth results in a dense mat of turfdeveloping quickly. The dense mat providesthe ideal fast and uniform putting surfacedesired by course superintendents.

The greatly enhanced rooting abilityis caused by two factors. First, the elimi-nation of the layer of soil allows thewashed sod to initiate its roots into thesand layer quickly as the root systemsearches for nutrition and water. Second,the process of pressure washing the sod toremove the soil actually stimulates rootgrowth by encouraging the turf ’s lateralroot stems to produce more root initia-tion points.

It is the ability of soil-free sod toestablish itself so quickly and with vigourthat is the key to its exceptional perfor-mance. The rapid establishment of theturf allows course superintendents toadapt the green to course specificationsmuch sooner than would otherwise be possible. Top dressing operations andreducing the height of cut can beginquickly. While each green restoration isunique, a three-week “time to play” turn-around is not unusual depending onexisting environmental conditions. Soil-free sod offers the advantages of smooth,healthy turf associated with seeded greenswith all the convenience, includingspeedy installation, of sod.

BENEFITS OF GOING SOIL-FREEThere are a number of other benefitsassociated with the use of soil-free sod.With, the layer of soil eliminated, soil-free sod can be laid to match the sandprofile of a green exactly as it is designed.

TURF & MAINTENANCE

Turfgrass sod is processed using specialized patented machinery to remove all of the attached soil

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Chris is chief of agronomy andhead of the turf solutions divisionat Manderley Turf Products. Chrisjoined Manderley in 1978, and has been instrumental in buildingthe company to its current position as Canada’s largest sup-plier of turfgrass and solutions.www.manderley.com

CHRISHOPE

Absence of the growing medium makes soil free turfgrass sod lightweight and suited to refrigerated transport

TURF & MAINTENANCE

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Soil-free sod is free of thatch and free ofpathogens so there is much less potentialfor contamination that can sometimesresult when introducing soil-based sod tonative soil. The absence of soil also makeswashed sod lighter and easier to handleand transport. However, washed sodrequires quick handling and installationupon delivery to prevent the delicate,exposed roots from drying out. It is criticalto water soil-free sod as soon as it is laid out.

The disadvantages of going with asoil-free alternative primarily boil downto its up-front cost. There is a premiumto be paid using soil-free sod, however it’sa cost that a mounting number of courseoperators and owners are willing to bearto deliver immediate results for golfersand avoid the inconvenience and loss ofrevenue as a result of closed greens. Also,there is the growing mindset that whilethe upfront costs of using soil-free sodmight be a higher than traditional sod,the investment is worth it over the long-term to avoid the inevitable downstreamcosts to maintain an unhealthy green orto re-restore or replace the green fromscratch. Course superintendents shouldalso keep in mind that soil-free sod is nota fix for underlying or systemic problemsbeneath. As such, before installing anynew surface it is important to fullyunderstand the reasons why turf mightbe having difficulty.

And, as with any course restorationproject, effective communication to play-ers and members to keep off the greenwhile it is being restored is essential toensure that everyone is aware of whenand why a green is not to be played on.

NEW STANDARDOnce a curiosity, soil-free turfgrass

sod is now widely accepted as the stan-dard for establishing turf that meetsUSGA specifications and when rapidturnaround is required. It’s not surpris-ing that a growing number of golfsuperintendents, administrators anddirectors are recognizing the advantagesand benefits of using soil-free sod, mostsignificant the ability to establish aworking green in very little time whilemeeting the highest standards for greenconstruction and restoration. The prosand cons of going soil-free are worthserious consideration by any course facingthe need to make course renovation aspainless as possible for members andplayers.1 Beard, James B.: Washed Sod, Grounds

Maintenance, August 1994Davis, William B. and Pratt, Charles A.: WashedVersus Unwashed: A Study in Sod Rooting, GolfCourse Management, May 19983