Aeration and CultivationMaking Sure the Cure Is Better

Than the Disease

Soil modification resulting from aeration andtopdressing.

Layers like these can block drainage and im-pact root growth.

"Sports turf managers have beenguessing for too long about why

' or how to aerify." These are thewords of Tom Mascaro, who invented of oneof the first aerifiers (aerators) for turf in 1946.He has no doubt about the value of aera-tion, he just can't understand why it tookthe turf industry so long to adopt it as a keymaintenance tool.

"The original idea was simply to cultivateor disturb the soil beneath the turf surface,"he states 41 years later. "Anything you doto disturb grass causes it to grow faster."That factor alone justifies aeration to Mas-caro. When you add relief of compaction,deeper penetration of chemicals, speeding

up decomposition of thatch, greater infiltra-tion of water, breaking up subsurface layers,amending heavy soils or creating a betterseedbed for overseeding, it becomes impos-sible to select one machine that will accom-plish all these tasks in all soil conditions.

"Before using a particular aerator, youreally should identify the problem you aretrying to solve," points out Dr. Bob Carrow,associate professor of grasses and turfmanagement at the University of Georgiain Experiment. "Aeration, or cultivation asI prefer to call it, isn't as straight forwardas people think. There is no one piece ofequipment for all problems." Carrow is halfway through a two-year study on cultiva-

Wind-blown silt caused this surface layer tobuild up on greens.

tion supported by a grant from the UnitedStates Golf Association Green Section. Hehas collected as much of the existingresearch on aeration as he could find to helpguide him through his project.

"One of the biggest hurdles we have toovercome is realizing that all types of cul-tivation create some degree of compactionin the soil," states Carrow. "The importantthing is to look at the net benefit—in otherwords, making sure that the amount of com-paction relieved is greater than the amountof compaction caused by the machine."

The second major factor is surface dis-turbance. "You don't want to tear up the turf

continued on page 22

May, 1988 21

Aeration and Cultivationcontinued from page 21

during the playing season or before a majorgolf tournament," he remarks. "Certain typesof aerators should be used at certain timesbased upon the use of the turf, soil condi-tions and weather. Sometimes you have tosettle for light or moderate cultivation witha small amount of improvement instead ofsevere cultivation and an unplayable sur-face. Each type of machine has its placeand time."

Relieving compaction is the most widely

Land Pride's drum aerif ier.

known use for aeration equipment. "You canget compaction in a flower pot," says Mas-caro. As the silts and fines filter down intothe pore spaces around soil particles, thesoil becomes harder and drainage is slowed.Pressure exerted on the surface compoundsnatural compaction to reduce the amountof space between soil particles. Where awell-textured soil would contain 50 percentsolids, 25 percent air and 25 percent water,a compacted soil contains more solids andless space for air and water.

"A good example is prairie soil," Mascaropoints out. Prarie grasses sent their rootsinto the dead mineral matter that was thereoriginally to open up pore spaces. As theroots died, air and water took their place.The result was a naturally textured soil thatserved as a good root zone. Without dis-turbance, this soil ecosystem remained inbalance. But when man moved to theprairies to farm and ranch, he upset thebalance and today must cultivate to relievesoil compaction.

To say that sports are the equivalent ofa herd of cattle on soil is not farfetched. Thepounds per square inch placed upon soilby golfers, football, baseball and soccerplayers, turf vehicles and maintenanceequipment is not that much different. Byintensively using turf for sports, we createcompaction that must be periodically reme-died if the turf is to recover quickly.

The majority of aeration or cultivationequipment is designed to relieve compac-tion in the top three inches of soil. The unitsdrive tines or blades into the topsoil usingvarious methods.

The original concept utilized star-shapedblades mounted on an axle or drum. As atractor rolled the aerator over the turf, theweight of the unit forced the blades into andout of the soil. The openings left behindallowed improved penetration of air, water22 sportsTURF

and fertilizers. Since soil was forced downand to the side when the spike entered thesoil, little direct relief of compaction wasprovided. By creating pathways in the soil,natural processes that improve soil texture,such as root penetration and freezing andthawing, could indirectly benefit the turf. Thismethod of cultivation is referred to todayas pin spiking.

Inventors, such as Mascaro, took the con-cept a step further by replacing the bladeswith open spoons or hollow cylindrical tinesthat pulled a plug or core of soil out of theground. They also developed other methodsof driving these tines into the ground, rangingfrom drills to sets of arms on a crankshaft.By removing cores of soil, the density orhardness of the soil around the holes wasreduced. It has since been confirmed atMichigan State University that these tinesinitially compact the soil on the walls andbottom of the holes. As the hole walls col-lapse, the net result is reduced compactiondown to the depth of the tine.

Repeated aeration at the same depth,however, can create a compacted layer in

Terracare pull-behind aerator.

some soils at the bottom of the holes, usuallybetween two and three inches. This has ledto development of cultivation technology thatbreaks up this subsurface layer. How fre-quently "deep cultivation" is required canbe based on the soil type, the frequencyof shallow cultivation, the closeness of thetine pattern and whether or not the tine depthis altered between aerations.

Another type of aeration, called "shatter-core," has been developed to cultivate alarger volume of soil around holes madeby tines or blades. The action of the tineor blade in the soil shatters or disturbs thesoil beyond the hole wall. Instead of bring-ing a core of soil to the surface that mustbe removed or broken up, this techniquerelies on solid tines or specially designedblades to disturb the soil below the surface.Manufacturers of shattercore equipmentrecommend that soil moisture levels shouldbe lower than they would be for conventionalcore aeration.

"If your goal is to control compaction,"says Carrow, "the best thing you can do isdevelop a schedule of assorted cultivationtechniques timed to consider surface dis-turbance, weather conditions and use ofeach turf site at different times of the year.If a green is showing signs of stress a week

before a tournament, you might considerpin spiking to gain maybe five percentimprovement, instead of core cultivating."Another option is to switch to a smaller tine,possibly even a small solid tine, to keep sur-face disturbance to a minimum. More effec-tive methods of cultivation should be sched-uled and carried out after the tournamentand periodically throughout the growingseason.

One scale of the severity of core cultiva-tion is the percentage of soil removed bythe aerator. The size and pattern of tines

Ryan Tracaire rolling aerator.

on aerators can vary this percentage fromone to more than ten. A figure between twoand three percent is common for standardturf aerators while some greens aeratorscan remove more than ten percent.

Tines range in size from 1/4-inch to 3/4-inch in diameter. Larger tines remove moresoil. Patterns, or the spacing between tines,generally range from four by seven inchesfor some rolling-type aerators down to oneby two inches for some crankshaft models.Making more than one pass with an aera-tor can create a tighter pattern. In additionto the tine size and pattern, tine depth isalso an important consideration when itcomes to the volume of soil being removed.A large tine on a tight pattern can removeup to 15 percent of the soil.

Carrow's point is that the sports turfcontinued on page 24

Mmm

Holland Aerway deep cultivator.

HARD PLAYING FIELDSCAUSE INJURIES!Problem:COMPACTIONThe primary cause of soil compaction isheavy foot or vehicular traffic. That's whyit's such a common problem on playingfields. Because compaction drasticallyalters the physical structure of the soil, itbecomes a poor medium for the growth ofturfgrass roots, wastes valuable water andnutrients, and results in higher main-tenance costs. Compacted soil stuntsroot growth, rendering turfgrass morevulnerable to periods of stress. You don'tjust have a rock-hard surface in whichturfgrass has great difficulty growing . . .you also have an accident waiting tohappen!

Solution:QUALITYCORE AERATIONVertical tine core aeration admits muchneeded water, oxygen and other nutrientsinto the soil, allowing turfgrass root sys-tems to penetrate deeply. Combiningdeep penetration with a close hole patternexpedites the horizontal spread of thesevital elements. If you want the best foryour athletes you'll insist on quality coreaeration by the SALSCO FTA-60-24.This "super achiever" is capable of aerat-ing up to 60,000 square feet per hour.Aerating with the FTA-60-24 Core Aeratorwill give you greener, softer and safer play-ing fields.

Call or write for your free copy of our informative booklet onvertical tine core aeration:

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Toro crankshaft greens aerator.

Aeration and Cultivationcontinued from page 22manager should have the ability to adjustthe severity of cultivation to match turf useand weather conditions. For example, a foot-ball field constructed of heavy soil shouldbe severely cultivated in the spring by remov-ing up to ten percent of the soil through coreaeration. During the playing season, whensurface disturbance needs to be kept to aminimum, the sports turf manager couldswitch to pin spiking or small solid tines.After the last game, moderate core aerat-ing can then remove between three to fivepercent of the compacted soil.

Carrow cautions that severe core aera-

tion should be avoided during excessivelyhot, cold or dry periods. In fact, if a turf areadoes not have an irrigation system, severecultivation could do more harm than good.

Heavily-used, severely compacted sportsturf may periodically require deep cultiva-tion in addition to frequent aeration of thetopsoil. Deep cultivators operate on a num-ber of different principles to cultivate andshatter the soil to a depth of four to teninches. Carrow's preliminary results haveshown that deep cultivation increases rootdepth, an important factor in drought andwear tolerance. "We've discovered that com-paction can stimulate surface rooting," statesCarrow. While the turf may actually increaseits root structure, these roots are nearer tothe surface where they are exposed to trafficand the elements.

"One very important thing to remember,"says Carrow, "is turf under stress does notrecover as quickly as healthy turf. Cultiva-tion also adds to the stress placed on theturf at first. It's critical to fertilize before orimmediately after cultivating to give the turfthe ability to heal up rapidly."

The value of cultivation in controllingthatch is also gaining recognition. The organ-isms which break down dead plant materialare sensitive to soil conditions. Excessivewetness or dryness caused by surface com-paction can disrupt their role in breakingdown thatch. Cultivation that breaks throughcompacted soil layers improves the environ-

Ryan Greensaire II.

ment for these beneficial organisms. Fur-thermore, by relieving compaction, turfgrassrooting should shift in favor of deeper rootingas opposed to surface rooting. As surfaceroots age and die, they add to the amountof material in the thatch layer that organ-isms must break down.

Core aeration can remove up to 15 per-cent of the thatch on the surface. Dr. Mar-tin Petrovic at Cornell Univeristy in Ithaca,NY, says core aeration can actually removemore thatch than some verticutters ordethatching units. Furthermore, if core soilcontaining beneficial organisms is mixedinto the thatch layer, decomposition isimproved. By breaking the cores up witha drag or vertical mower and brushing them

continued on page 26

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•Any Seed or Seed/Fertilizer, Box Combination Can BeMounted. Brush On Spiker Is Optional.MODEL SU-66O SEEDERSingle Section Large Capacity Seed Box. Seed controlledby precision metered gears. Easy mounting and dismount-ing agitator to insure constant flow of seed.

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o O

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Closeup of quadratines on Green Care CoreMaster 12.

Aeration and Cultivationcontinued from page 24

into the thatch, the layer of dead vegeta-tion is recharged with fungi, bacteria andother organisms which feed on it. Manysports turf managers find aeration and recy-cling the cores back into the soil more prac-tical than removing thatch by power raking

and disposing of the debris.Some superintendents utilize core aer-

ation with topdressing to gradually amendheavy soils. By brushing sand or sand mixedwith humus into core holes after each aer-ation, heavy soil is replaced with a grow-ing medium that resists compaction anddrains better. The improvement is small, but

it may provide some relief when reconstruc-tion is impractical. One type of deep culti-vation consists of a vibratory plow that injectssand into narrow channels in the soil.

Manufacturers have developed machineryto reduce the amount of labor required tohandle large volumes of soil and amend-ments. They have designed core collectorsto simplify removal of cores on greens. Theyhave also developed topdressers that dis-tribute material evenly over large areas.Combined with cultivation methods, thesemachines allow turf managers to control thetexture of playing surfaces more effectively.

One obstacle to managing soil texture hasbeen the inability of the sports turf managerto reliably measure soil hardness. He cansend soil samples to a laboratory for anal-ysis, but that doesn't provide a quick wayof judging hardness or compaction in thefield. An athletic field manager needs toknow if certain fields or portions of fieldsare becoming too compacted for playersafety and turf health. A superintendentneeds to know if his greens are approxi-mately the same firmness. Small raisedgreens may get hard faster than largershaded greens. Separate cultivation tech-niques and schedules may need to be deve-loped for each green.

Compaction meters range from simplespring-loaded rods to complex impacttesters. These devices not only allow theturf manager to compare the firmness of

The Leiy Turfterra" makes the ideal playing and riding surface with a consistenttop cushion and firm lower surface. Some of the most common applicationsare for use on: ball diamond infields, riding arenas, horse tracks and more.

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different sites, they can alert him if the soilis too wet or dry for cultivation. "Water isa good lubricant," explains Mascaro. "Youneed a certain amount of moisture for tinesto penetrate the soil to a desired depth."Diagnostic tools, such as compactiongauges, give the sports turf manager thecontrol he needs to plan and implement cul-tivation programs more effectively thanbefore.

A core sampler, a simple hollow rod orshaft that opens after a core is pulled, isdiagnostic tool that every sports turf managershould use regularly, says Mascaro. It notonly reveals subsurface layers, it can pro-vide important information on soil textureand moisture at various depths. "You cansee how deep roots are growing in a cer-tain area," says Mascaro. "Shallow rootsare a sure sign of a compaction problem."

Salsco crankshaft greens aerator.

Selecting an aerator or aerators can besurprisingly complicated. Rolling-type unitshave fewer parts that require service thancrankshaft types. However, a rolling-typeaerator may have 30 to more than 300 tinesthat will need to be replaced at some point.Crankshaft models typically have betweeneight and 12 tines.

Rolling-type tines enter and leave the soilat an angle, whereas crankshaft-driven tinesenter and leave the soil in a near-verticalmotion. As a result, the surface openingmade by the vertical tine is cleaner. Youmay not want to use a rolling-type aeratoron a green, but its speed makes it fasteron fairways and fields. Some manufacturershave recently increased the speed of theircrankshaft models to cultivate up to 30,000square feet per hour. One manufacturer hasmore than doubled that speed by doublingthe width of its crankshaft-type aerator. Arolling-type aerator pulled by a tractor in thesame period of time might do one to twoacres. "You have to look at the core pat-tern and depth for a true comparison," saysSal Rizzo, president of Salsco, Inc.

With the exception of the Holland Aer-way, deep cultivators are more complicatedmachines than rolling-type aerators. Theytoo require regular maintenance for relia-ble, long-term performance. For this rea-son, most deep cultivators are owned andoperated by specialized contractors.

One thing is very clear—you have to main-

tain aerators regularly if you expect themto work properly when you need them. "Youshould spend 30 minutes on maintenanceevery day you use an aerator," says Rizzo."That small degree of prevention can saveyou hours of downtime. After all, you shouldbe doing the same thing for your mowingequipment."

The other key to longevity of aerationequipment is evaluating the site and soilconditions prior to aerating. "Once you getoff a green and onto a sports field or fair-way, the hardness and uniformity of the soilchanges drastically," warns Clarke Stapleswith Cushman-Ryan. "The machine and thetines must work harder and for a longer

period of time. The operator needs to beon the alert for roots, rocks and other hardobjects in the soil at all times. You may needto vary the depth of the aerator due to soilconditions."

One reason Carrow thinks cultivation hasbeen accepted as an important part of sportsturf maintenance is golfers and players arebeginning to understand that a small amountof inconvenience caused by holes or soilcores is a small price to pay for overallimprovement in the turf throughout the year.In fact, if they don't see some signs of cul-tivation during the year, they may wonderif the superintendent or sports turf managerknows what he is doing. <Q>

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STMA ANNUAL MEETINGPLANNED FOR DODGERTOWN

The Board of Directors of the Sports Turf Managers Associa-tion (STMA) has voted to launch its own independent annualmeeting January 13-15, 1989 at Dodgertown, the Los AngelesDodgers spring training facility in Vero Beach, FL. For three yearsSTMA held its annual meeting in conjunction with the Golf CourseSuperintendents Association of America Show. Last year, STMA'smeeting was part of the Pro Show in Dallas, TX.

"We felt that STMA now has the size, strength and resourcesto step out on its own with a show," said Mark Hodnick presi-dent of the 700-member organization. "The board is grateful toGCSAA for its help in the past, but it's time to move on."

The Dodgertown event will feature two half-days of seminarsand two half-days of trade show. Demonstrations of athletic fieldequipment and supplies will be presented in addition to an awardsbanquet. Showgoers will also be able to see the Dodgertowncrew prepare for spring training.

The event was scheduled to fit between football and baseballseasons, said Dr. Kent Kurtz, executive director. "We hope mem-bers and other sports turf managers will also take advantageof our one-day institutes to be held this summer at Du Page Collegein Glenn Ellyn, IL, and at the College of Holy Cross in Worcester,MA." The oldest institute is held every March at California Poly-technic University in Pomona. STMA is in the process of developinga new institute in Seattle, WA, or Portland, OR. Since the annualmeeting will be held in Florida, the Daytona Beach institute normallyheld in September will be delayed until the fall of 1989. "We planto move the show each year so members from across the coun-try have a chance to attend," said Hodnick

Interested sports turf managers and exhibitors should con-tact Melissa Merritt, STMA, 400 N. Mountain Ave., Suite 301,Upland, CA 91786, (714) 981-9199.

MAJOR LEAGUESGET FEEL OF OMNITURF

Considering that artificial turf has been a major factor in recentWorld Series, Major League Baseball managers take notice whennew types of artificial turf enter the market. This spring 11 teamsgot their first look at Omniturf at the Kansas City Royals springtraining center at Boardwalk and Baseball near Orlando, FL.

The sand-filled artificial turf surface was installed on the infieldof the new stadium last fall. The outfield is Tifway bermudagrassoverseeded with perennial ryegrass. This spring ten teams visitedthe facility to play the Royals in 17 exhibition games. It was theirfirst exposure to the artificial surface. Many of the teams playtheir home games on AstroTurf.

Omniturf consists of a one-inch-high carpet of polypropylenefiber blades, filled to within 1/4-inch of the top with sand. Thislayer is laid atop rubber pads and a rock sub-base. A drain pipesystem runs through the sub-base.

The five other practice fields at Boardwalk and Baseball arebermudagrass. The Class A Baseball City Royals have beguntheir schedule of 70 home games at the stadium. College andhigh school games will round out the schedule for this year.

28 sportsTURF

Irrigation system repairs can usuallybe kept to a manageable level if youfollow a few simple but orderly steps.

The first is to do what John Wayne did inhis low-budget cowboy movies of the early1930s—head them off at the pass.

We spoke to some experts on thesubject—real experts, in that they eitherspend their days repairing systems or havegone on to become consultants based ontheir years of experience in the field. Theyagree that a regular maintenance sched-ule to avoid repairs should be first on any-one's list of things to do.

In order to make such a schedule mosteffective, however, you first need to knowwhich components in a system are mostlikely to need periodic maintenance—and,should the varmints still get through thatpass, which are most likely to need repairs.

You also have to know how to detectproblems when they occur—hopefully beforethey become serious, though this isn't alwayspossible.

These three stratagems have beenapplied by each of our experts to some orall of the following elements, depending ontheir particular expertise and interests: elec-trical, hydraulics, pressure, flow, controls,sensors, valves, and pump systems.

Bill Derryberry spoke to us from his officein Scottsdale, AZ, where he has a thrivingpractice as an irrigation consultant and haswritten and published a book, "Troubleshoot-ing Irrigation Control Systems," which hesells by mail.

Derryberry began very modestly by say-ing, "People often ask me what kind of main-tenance I recommend for avoiding problemsin irrigation systems. And, frankly, I don'tsee a lot that you can do! It's not like chang-ing the oil regularly in an automobile engine."Then he proceeded to tell us plenty that youcan do. . . .

"Check to spot solenoids that are aboutto fail. Make sure your splices are correct.Keep your clocks clean, dry, and bug-free.Adjust and set all heads to their correctheight to avoid their being broken off by amower. Seek out broken heads frequentlyand repair them promptly. When you dorepair them, install flexible swing joints inorder to head off future damage. And, ofcourse, use swing joints on all new heads.

"Most problems involve breakage causedby incorrect installation. Ninety percent ofthat involves failure to use swing joints, orfailure to use them properly, plus settingthe heads improperly. Few people appreci-ate how critical it is to set a head within ahalf-inch of level, and flush with the finishedgrade."

Getting down to details, Derryberry hadthis to say about the various elements ofan irrigation system and what can go wrongwith them:

"Electrically, probably the biggest andleast-understood failing is deteriorating sole-noids. Most of the time you can anticipateearly failure of solenoids by a simple ohm-meter test at the clock, instead of walking

continued on page 30

A Guide toIrrigation Repairs

Technician checks resistance for each valve at controller.

May, 1988 29

Sprinkler heads should be flush with the surface to avoid damage by maintenance equipment.

Irrigation System Repairscontinued from page 29all over to check the whole system per-sonally. Ohmmeters directly measure elec-trical resistance in ohms, so you can seeat a glance if something's wrong."

Simply comparing the resistance in var-ious stations will disclose which solenoidsare shorted or partially shorted, Derryberryexplained. When you do find a solenoid ineither condition, "Change it now," he urged,"to avoid a future service call. Don't try totalk yourself out of it. Don't let it go!"

Turning his attention to components mostlikely to fail, he said, "Aside from ordinarypipe breakage and vandalism, the singlegreatest cause of service calls—perhaps90 percent of the remainder—is for remote-control valves, or RCVs."

His maintenance advice in this regard:"Ohmmeter readings every six months wouldprobably be the most important thing youcould do. Inspect all valve pigtail splices,and replace those which are not properlywaterproofed. If you have just inherited alarge project, don't fail to go through andcheck all those RCV pigtail splices—because electrical shorts cause confusingsymptoms and misdirect repair efforts.Therefore you should at least eliminate suchsymptom confusion by seeing to it that youhave good splices first.

"On the ohmmeters, you'll get differentcontinued on page 32

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