Customized CultivationWhat is the goal of your cultivation program?The most effectivelong-term benefits are achieved from customized cultivation.

BY BOB VAVREK

Cultivation ... the word is derived fromthe Latin word cultus, to till. Cultivatingor tilling the land became important

long ago when prehistoric people evolved fromnomadic hunter-gatherers to farmers. Indeed,cultivation was around long before golf courses.How long? References regarding cultivation canbe found very early in the Bible (Genesis 3:23).

There aren't many references made aboutcultivation in early turf management publications.Authors of the few early references were generallyskeptical about the benefits of cultivating estab-lished turf due to the potential damage to rootsystems and disruption of the playing surface.

Over time, the importance of modifying soilstructure to improve growing conditions for turfbecame apparent to astute observers like TomMascaro. He invented and patented the firstaerifier for turf grass in 1946 and the verticutter in1952, tools to remove thatch from greens. Theneed for more aggressive cultivation equipmentcoincided with the increasing popularity of golf

and heavier play on old soil-based greens. Sincethen, play and the use of motorized carts haveincreased dramatically. Consequently, the impor-tance of developing a sound cultivation programis greater than ever.

Today's playing surfaces need to be cultivatedfor two primary reasons. They are affected eitherby compaction or excess organic matter (OM)accumulation. When one of the primary prob-lems occurs, many secondary problems are sure tofollow. For example, severe soil compaction canlead to weed encroachment, decreased rootgrowth, low soil oxygen, poor drainage, and wetspots. Excess OM can lead to black layer, puffi-ness, scalping, localized dry spots, footprinting,and shallow rooting.

Turf managers often treat the symptoms ofcompaction and excessive OM accumulation andtend to ignore the primary problem. For example,raising the height of cut to alleviate scalpingacross a thatchy playing surface reduces stress tothe turf but does not address the problem ofexcess organic matter accumulation.

COMPACTIONSoil compaction causes an increase in bulkdensity (mass/unit volume) due to a decrease insoil porosity. Pore space is necessary to get oxygento the roots, hold water for the turf, and aidrooting. Foot traffic, cart traffic, constructiontraffic, and maintenance equipment traffic are thecommon causes of compaction on golf courses.

There is never a shortage of compaction atpopular, heavily played courses. When trafficbecomes concentrated, compaction increases,particularly when soil is wet. Tees, fairway turfadjacent to bunkers, and turf along the entranceand exits to greens are often affected bycompaction. Initial golf course construction andconstruction associated with renovation willcause localized compaction as well.

Standing water in thehole after moderateto heavy rainfall is anindication that greenswould benefit frommore aggressivecultivation. Deep-tineor deep-drill cultivationcan improve internaldrainage through oldsoil-based greens.

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Water injection tendsto fall in and out offavor among super-intendents. Limitationsof slow ground speedand short-lived benefitsare more than offset byits ability to relievecompaction and enhancewater movementthrough the soil profilewhile causing relativelylittle disruption to theplaying surface.

EXCESS OM ACCUMULATIONExcess OM accumulation is a common cause forfailure of or problems with new sand-basedgreens.! OM is constantly recycled into the upperrootzone of greens when shoots, roots, stolons,and other plant parts die back and are replacedthroughout the season. Soil microbes decomposeOM and under optimal conditions the rate ofOM decomposition can keep pace with the rateof production. However, this rarely occurs ona golf course, where watering, high inputs ofnutrients, shade, climate, and other factors eitherincrease tissue production or inhibit microbialdegradation.

New ultra-dense varieties of bentgrass andbermudagrass are especially susceptible toexcessive OM accumulation due to high shootdensity and their ability to grow a deep, denseroot system in a sand-based rootzone material.Working topdressing into a tight canopy of turfis a challenge, and much of the sand can beremoved with the clippings. Undiluted OM willquickly clog pore space and make the surface ofthe new greens wet and spongy. Excess moisture

at the surface creates playability issues, such aspitted ball marks and footprinting. Secondaryconcerns include moss/algae encroachment,scalping, black layer, and shallow rooting.

Excess OM is not difficult to diagnose; you cansee it and feel it. A discrete dark, spongy layer inthe upper soil that holds excess water is hard tomiss, yet many turf managers are in denial.

Quantifying the amount of OM in the soilprofIle is another story. Different labs use differenttests and unique methods for preparing a sample.Don't compare the results from one lab toanother. However, measuring and comparing theOM content from healthy versus problem greenscan be helpful and provide the baseline valuesneeded to monitor the progress that occurs overtime when cultivation and topdressing programsare modified.

MAKE THE RIGHT CHOICECultivation can help relieve compaction andmanage OM accumulation. The key is to choosethe right cultivation tool for the job ... remem-ber the classic line from the movies - "You don't

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bring a knife to a gunfight." Far too often theleast disruptive, and least effective, cultivationtechnique is used to minimize golfer inconven-ience, with little chance of addressing the prob-lem. The following outline can help guide youthrough the process of choosing the mostappropriate form of cultivation. Keep in mindthat serious problems generally require a seriousand often disruptive remedy. OM buildup andcompaction usually develop over a period ofyears, so it takes time for corrective managementpractices to begin to improve the condition.

OM MANAGEMENT OPTIONS

Highly Effective

Standard 12"- %" hollow-tine cultivationAdvantages• Removes organic matter from soil profile whencores are removed.• One pass with %" tines on 1.25" centers affects:::::13% of the surface.Disadvantages• Temporary surface disruption.• Significant cleanup.• Close center cultivation causes surfaceinstability.Comment• Topdressing and rolling can alleviate post-cultivation instability.

• An excellent pre-treatment for greens beforetopdressing.• Useful for management of ultra-densebentgrass/bermudagrass.Disadvantage• Considerable turf thinninglinjury.

Vi" Hollow-Tine Cultivation (Quadratines)Advantages• Removes OM from the upper soil profile.• Minimal disruption and rapid recovery.Disadvantage• Only affects 2% to 3% of the surface, depend-ing on the spacing. Has limited impact with onetreatment.

Deep- Tine Cultivation (Hollow Tines)/Deep DrillAdvantages• Deeper penetration than standard coringoperations .• Removes minimal OM from the soil profile .Disadvantages• Slow recovery following use of large-diametertines. '• Affects minimal amount of surface .Comment• Should not be used as a substitute for standardhollow-tine cultivation where excess OM is aprimary problem.

High-tech options forcultivation are great, butdon't forget that plentyof simple, inexpensive,and effective cultivationequipment can be foundon many courses.

Deep Scarification (Graden, Sisis, etc.)Advantage• Wide blades and close spacing can affect:::::11%of the plaYing surface .• Removes significant amounts of OM.Disadvantages• Labor-intensive cleanup .• Surface instability .• Lines in greens distract golfers long after initialturf recovery.Comment• Ideal cultivation tool for sodded greens andnew sand-based greens where excess OM islocated near the surface.

Effective

Carbide- Tipped Vertical MowingAdvantages• Capable of removing OM in the upper soilprofile while causing minimal surface disruption.

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Deep-tine aeration iscommonly employedacross greens, but thisoperation is just aseffective across tees,fairways, and roughs.

Marginally Effective/lneffective

StandardVertical MowingAdvantage• Effective pre-treatment to topdressing greens.Disadvantages• Limited depth of penetration .• Removes minimal amounts of OM.

Solid Tine/Water Injection/Air InjectionAdvantage• Can create temporary channels through anOM layer to improve balance of air/moisture inthe soil profile .• Limited to no surface disruption.Disadvantages• Does not remove OM .• Transient benefits.

SpikingAdvantage• Can improve balance of air!moisture in uppersoil profile affected by excessive OMaccumulation .Disadvantages• Does not remove OM .• Transient benefits .

COMPACTIONMANAGEMENT OPTIONS

Highly Effective

Standard Hollow-Tine CultivationAdvantage• Leaving holes open will reduce bulk densitywhen side walls collapse.

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Disadvantages• Relatively shallow depth ofpenetration .• Surface disruption .• Labor-intensive cleanup .• Potential for hardpan development.

Deep Tine/Deep DrillAdvantages• Affects soil beyond depth of standardhollow-tine cultivation .• Adjustable depth of penetrationrelieves/prevents hardpan development .• Kicking action of deep tine fracturessoil.Disadvantage• Limited ability for penetration intorocky soils .• Slow operation.

De-compactors (Blec GroundBreaker,Verti-Quake, etc.)Advantages• 8" depth of penetration .• Capable of fracturing compacted soilsbetween slits.• Minimal disruption.Disadvantages• Limited availability.• Limited effectiveness in rocky soils.Comment• Good potential for relieving compactionfollowing fairway regrading/renovation work.

Effective

Air Injection Tines (SisisAer-Aid System)Advantages• 5" depth of penetration .• Injects air through tines.Disadvantages• Availability of equipment .• Limited effectiveness in rocky soils .Comment• New cultivation option from Europe .

Water Injection/ Air InjectionAdvantages• Deep penetration.• Unaffected by rocky soils.Disadvantages• Cost of equipment/contract services.• Slow ground speed.• Short-lived benefit.

Marginally Effective/lneffective

Solid-Tine CultivationAdvantages• Can shatter soil under ideal soil moistureconditions .• Speed, minimal disruption.• No cleanup.Disadvantage• Potential for hardpan development .

SpikersAdvantages• Speed and minimal disruption .• Low-cost equipment.Disadvantage• Minimal depth of penetration.

REFERENCES1. Carrow, R. N. 2003. Surface organic matter in bentgrassgreens. [Online] USGA Tuifirass Environ. Res. Online .2(17):p.[1-12].

BOB VAVREK helps superintendents customize theirmaintenance operations at coursesacrossMichigan,Minnesota, and Wisconsin .

The most effective wayto remove excessorganic matter from theupper soil profile hasnot changed much overthe years. Cultivate withhollow tines, removethe cores, and fill theopen holes with sand.

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