modified rootzones & current water management technologies...

12 SportsTurf | January 2012 www.sportsturfonline.com

FieldScience | By Stephen T. Cockerham, Bernd Leinauer, Paul E. Reike, James A. Murphy, and Robert Green

MODIFIED ROOTZONES FOR EFFICIENT WATER USE

Soil uniformity. Uniform soil condi-tions make it easier to grow uniform turfand provide more efficient irrigation.However, turfgrass is frequently grownon nonuniform modified soils where top-soil has been removed or mixed with sub-soil. Sod is often laid on compactedsubsoils, which limit rooting into theunderlying soil.

Soil variability increases the need forsite-specific management in irrigation pro-gramming, using the knowledge of soilproperties such as texture, structure, or-ganic matter content, compaction,drainage, slope, fertility, and pH, as well aslighting and air movement. Water relationsin soils depend on retention and transmis-sion of water: soluble salts can control howmuch water is available to roots in salt-af-fected soils. As a soil dries or as soluble saltcontent increases, less water becomes avail-able for plant uptake.

Sand-based designs. Sand-based profilesthat have relatively narrow particle size dis-tribution are widely used with or withoutamendment for highly trafficked turf areas

such as golf putting greens and other sportsturfs to ensure adequate water infiltration,percolation, and drainage, and to preventthe buildup of excessive soil water content.Profile designs that encourage the develop-ment of a water table can conserve water.These designs on limited slopes and whendrained to field capacity can have a watercontent distribution ranging from unsatu-rated and well-aerated at surface depths tonearly saturated at the lowest depths.

Placing a finer-textured sand overcoarser material such as gravel creates azone of greater water retention (a perched,or suspended, water table) in the sandabove the interface with the gravel layer.For example, the USGA Green Sectionspecifications for putting greens use a 2-layer or 3-layer profile. The 2-layer profileis most widely used and has a 300-mmsand root zone mix of a specific particlesize distribution placed over appropriatelysized gravel. Drain tiles are installed in thegravel layer. During construction, thesespecifications are sometimes followed care-fully, sometimes not; if not, undesiredconditions may occur in plant-availablewater or drainage patterns.

The California design is a 1-layer sys-tem consisting of a specified well-drainingsand placed over compacted (imperme-able) native soil. Drain tiles are installed intrenches in the native soil. Water retainedat the bottom of the root zone is moretypical of a perched water table if there isvery limited or no drainage into the un-derlying soil.

Drainage from the 2-layer USGA put-ting green profile tends to be independentof the sand mix, while the 1-layer Califor-nia green profile drains slower, with finersand mixes. Thus, the 1-layer profile tendsto hold more water for turf use than doesthe 2-layer profile. The 2-layer profile hasonly a short-term effect on the perchedwater table due to the downslope subsur-face movement of water. If the root zonemix is too deep, water stress increases,leading to localized dry spots, especially inthe highest elevations of a putting green. Ifthe top mix is too shallow on puttinggreens, it may be difficult to place the holeliner, and wet areas may occur, which canenhance development of black layer.

Better turf performance has been ob-served on root zones that retain morewater with reduced rooting compared withroot zones that retain less water withgreater rooting. In sand-based root zones,greater rooting depth has not been relatedto better turf performance or greater effi-ciency in water use. There is evidence tosuggest that greater water conservation can

Turfgrass water conservation essentials:modified rootzones & current water management technologies

TURFGRASS WATER CONSERVATION is not just a concept of theminimum amount of water that can be used for turfgrass survival, it isalso the concept of optimizing water use as a significant factor in gettingthe maximum performance from turf and not wasting water. Key ele-ments of this concept are modifying root zones to promote optimal turf

growth and taking advantage of improvements in turf irrigation technology.

Further ReadingEstablishing and Maintaining the Natural Turf Athletic Field. 2004. S. T. Cockerham, V.

A. Gibeault, and D. B. Silva. Oakland: University of California Division of Agricul-ture and Natural Resources Publication 21617.

Handbook of Turfgrass Management and Physiology. 2008. M. Pessarakli, ed.Boca Raton: CRC Press.

Turfgrass and Irrigation Water Quality: Assessment and Management. 2009. R.R. Duncan, R. N. Carrow, and M. T. Huck. Boca Raton: CRC Press.

Turfgrass Water Conservation. 2011. 2nd ed. Oakland: University of CaliforniaDivision of Agriculture and Natural Resources.


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be achieved with sand-based root zonesthat retain more water.

Subirrigation. Subirrigation can use 70to 90% less irrigation water than surfaceirrigation. Drainage tiles placed on top ofplastic liners in subirrigation systems canbe closed to prevent leaching. These tilescan be attached to pumps to draw waterout or pump water into the sand profile.The water table can be raised or lowered asneeded, depending on root depth. Theparticle size range and depth of the sanddictate the degree of capillary rise of water.Problems with subirrigation include man-aging high levels of soluble salts andsodium, as well as maintaining uniformroot zone water content in sloping puttinggreens.

Topdressing with sand. Repeated sandtopdressing increases infiltration on nativesoil putting greens and other sports turfs.Water that had previously run off slopingturf surfaces tends to be held in the sandlayer. When dry, topdressed sports fieldshave a lower surface hardness. However,hydrophobic soil conditions, as found inlocalized dry spots or dry patches, fre-quently develop in sand media. Thesespots often occur in areas where irrigationcoverage is inadequate, on slopes wherewater tends to run off rather than infil-trate, and on slopes facing the sun. Fullydeveloped localized dry spots are difficultto rewet. Application of wetting agents,cultivation (aerification), thatch control,careful monitoring of soil water levels, andsyringing are the most common correctivepractices.

Avoiding black layer. Sand sports sur-faces grown with aggressive, high-densitycultivars of creeping bentgrass andbermudagrass can accumulate excess or-ganic matter, which can seal the surface,causing loss of roots, turf stress, and theformation of black layer. Managementpractices to prevent or remove black layerinclude providing more oxygen to the af-fected zone through reduced irrigation(with emphasis on syringing), cultivation,topdressing to prevent layer formation,improving drainage, controlling organicmatter, and monitoring fertility practices.

CURRENT WATER MANAGEMENT TECHNOLOGIES

Strategies to reduce unnecessary irriga-tion water use should include efficient irri-gation systems and scheduling irrigationbased on the actual water requirement ofturf needed to maintain a desired qualitylevel.

High-efficiency irrigation. To achievehigh-efficiency irrigation, minimize lossessuch as droplet evaporation, surfacerunoff, leaching, and wind drift. Correctsprinkler head selection and spacing canmatch water spray patterns with the shapeof the landscape, which helps avoid areasthat are over- or underirrigated. Dividelarger irrigated areas into hydrozones,areas of similar watering requirements.Consider subsurface irrigation systems:they have shown great potential for waterconservation, despite difficulties associatedwith determining spacing and depth oftrays, pipes, or emitters; higher cost of in-stallation; difficulty in monitoring and/ortroubleshooting damaged parts; potentialinterference with maintenance practices;and the inability to establish turf fromseed when irrigated below the surface.

Estimating irrigation amounts. Irriga-tion amounts can be estimated based onclimatic factors or calculated from theplants’ water status by monitoring soilmoisture or by using remote sensing tech-nologies that detect and quantify droughtstress. Evapotranspiration (ET) losses froma turfgrass stand provide an accurate meas-ure of irrigation water requirements. Theselosses have been closely correlated with at-mometer evaporation, open pan ET, and

potential (model) ET estimates (ETp andETo). ETp and ETo estimates are mostcommonly used when turfgrass irrigationscheduling is based on ET losses.

To match actual turfgrass ET, most ETestimates require adjustments in the formof multipliers or crop coefficients (Kc) tomeet local climatic conditions and specificmaintenance situations. Kc can vary from0.4 to 1.1, depending on ET reference,quality expectations, season, grass type,maintenance level, and micro- and macro-climate. Crop coefficients can also be usedto calculate irrigation amounts. Irrigationbelow 100% ET replacement (deficit irri-gation) does not necessarily result in a sig-nificant loss of turfgrass quality andfunction.

Several states offer automated, Web-based potential and reference ET valuesfor irrigation scheduling. In California,the most commonly accepted source of ETdata is the California Irrigation Manage-ment Information System (CIMIS, www-cimis.water.ca.gov).

Smart controllers. Smart controllers au-tomatically adjust to daily changes inevapotranspiration. Using them instead oftraditional irrigation scheduling can yieldwater savings as high as 80%. Some mu-nicipal water authorities and utilities haveintroduced rebate programs for installingsmart irrigation controllers. Irrigationscheduling based on soil moisture aims tokeep the root zone within a target mois-ture range by replenishing ET anddrainage losses. This is considered to bethe most intuitive way of determining howmuch and when to irrigate.

Soil moisture sensors. Soil moisturesensor technologies currently used toschedule landscape and turf irrigation in-clude dielectric sensors and heat-dissipat-ing sensors for measuring soil watercontent, and tensiometers and granularmatrix sensors (gypsum blocks) to measuresoil water potential. Both types have ad-vantages and disadvantages, and considera-tion must be given to the soil type, rangeof moisture measured, and expected soilsalinity.

Tensiometers estimate soil matric po-tential and do not require soil-specific cali-bration, but they do need regular

Several states offerautomated, Web-basedpotential and reference ETvalues for irrigation sched-uling. In California, themost commonly acceptedsource of ET data is theCalifornia IrrigationManagement InformationSystem (CIMIS,wwwcimis.water.ca.gov).

SportsTurf 15www.stma.org

maintenance. Granular matrix sensorsmeasure the electrical resistance betweentwo electrodes embedded in quartz mate-rial and correlate the resistance with thematric potential of the root zone.

To calculate irrigation requirementsbased on volume, soil moisture tension orsuction values must be converted to volu-metric soil moisture content using a mois-ture release curve. Dielectric sensors recordvolumetric soil moisture directly; measure-ments can be affected by the length of therods, soil texture, soil density, and soilelectrical conductivity.

Absolute moisture values can vary con-siderably over a landscape. If a sensor is in-stalled in a location representative of anirrigated area, and if it records moistureextraction between maximum and mini-mum over time, using this data can lead tomore consistent irrigation scheduling thanusing absolute values alone. Reported re-ductions in irrigation water applied rangefrom 0% to 82% when soil-moisture-

based controllers were used for schedulingcompared with either traditional or ET-based irrigation scheduling.

Crop water stress indices and normal-ized difference vegetation indices calcu-lated from remotely measured reflectanceof canopies have been suggested for irriga-tion scheduling of cool- and warm-seasonturfgrasses. However, to date no auto-mated remote sensing irrigation schedulingtechnology based on reflectance is com-mercially available.

How do modified root zones and cur-rent water management technologies relateto sports turf? The construction and man-agement of sports fields are directed tosupport the performance characteristics ofsafety, playability, durability, and aestheticsat some level of expectation. Water man-agement, as expressed in irrigation, is keyto meeting those expectations. Occasion-ally one finds a sport field that has beenbuilt by merely scraping off a spot andseeding it. Most often, though, the con-

struction involves modifying the root zonein some manner. In either case, the turfmanager must learn how to irrigate thatfield and ensure that the root zone growsthe best grass possible. Water managementtechnologies have been developed to makethat job just a little easier and to obtainthe highest efficiency from the water thatis applied. ■

This article was adapted from TurfgrassWater Conservation, Second Edition (Uni-versity of California Agriculture and Natu-ral Resources, ©2011, Regents of theUniversity of California), which was writ-ten by scientists for turfgrass managers anddecision makers to address many of the is-sues relating to turfgrass irrigation. Thisexcerpt is used by permission.

This publication, along with manyother useful resources for the turf profes-sional, can be found athttp://anrcatalog.ucdavis.edu/TurfLawns/


FieldScience | By Dave Radueg

turf and playing surface that couldbe compared with the world classpolo fields in Florida, California andArgentina that they are used toplaying on.

POLO BASICSOutside of polo circles, little is

known about the sport, so let’s startwith a few polo basics. These fields areregulation size, 300 yards long by 160yards wide. That is just less than 10acres per field. In perspective, eachpolo field is larger than 9 footballfields. This facility has two regulationplaying fields and a 3-acre practicefield. The entire length of each field islined with 11-inch high side boards.Although the side boards and end linesindicate the boundaries of the field ofplay, the areas outside of these bound-aries are not considered out of bounds.If the ball or the players move outsideof these borders, they simply continueplaying and move back into theboundaries. The field markings aresimple. The end lines are paintedacross the length of the field; the cen-ter is indicated with T-shaped mark-ings, and the 30, 40 and 60 yard linesare marked for penalty shots. The goalposts are 10 feet high, 24 feet apart,and are placed in the center of eachend line.

Each player rides 4 to 6 polo poniesduring the course of the game to keepthe ponies rested for maximum per-formance. Each team has four playerson the field, plus two umpires onhorses. The game is played in 6chukkers (periods) of 7 minutes each.So there are 10 horses running, stop-ping, and turning at full speed for 42minutes. Every step a horse takes cre-ates four divots. I don’t know howmany divots are made when 3 to 5games are played each week, but I canassure you, it is a lot, and that is wherethe job of turf manager comes in.

The divot operation is probably themost unique aspect of polo field main-tenance compared with other sports. A1,100-pound horse running at 40 mph

As I toured the J-5 Equestrian Centerduring my first interview, I knew immedi-ately that my first year managing polofields might provide a unique variety ofchallenges.

When these polo fields were built morethan 20 years ago, the intention was to usethem for polo as a hobby, not as a profes-sional polo facility. The fields were builtwithout drainage, without proper gradingand it appears as though 4 to 6 inches of

sandy loam was thrown on top of the nativesoil and rock that were left over from thecobblestone mine that the area was used forat the beginning of the century.

When our team, Valiente, took a lease onthe fields the team owner and players real-ized that in order to play at a competitivelevel, the condition of the fields would needto change dramatically. Valiente’s vision is tobring these polo fields to a level beyond pastexpectations and to create a standard for the

Polo fields:uniquely challenging turf management

AT THE BEGINNING OF 2011, all I knew about polo was thatPrince William liked to play the sport and that I could buy a t-shirtwith a polo player in the corner for more money than I am willingto spend on a t-shirt. As an assistant golf course superintendent,I didn’t even know that Colorado had polo fields.

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>> The fields were built without drainage,without proper grading and it appears asthough 4 to 6 inches of sandy loam wasthrown on top of the native soil and rockthat were left over from the cobblestonemine that the area was used for at thebeginning of the century.


FieldScience

and cutting at 180 degrees creates a whole new category of divot.Most of you have probably heard about the divot stomp, where thespectators enter the field between chukkers and stomp down thedivots. This is very helpful, but we only hold one formal eventeach year where we have spectators to fulfill this duty. The firstthing the turf crew does after each match is walk the field, flippingand stomping the divots. Doing this immediately is extremely im-portant so the divots don’tdry out. The field is thenrolled to keep a smoothsurface and to protect themowers from scalping themounds that each divotcreates. Now it’s time tofill 10 acres of turf that arecovered in divots wall towall. Sod is not an option.If a horse slips on un-rooted sod and breaks itsleg, then that horse, un-fortunately, has played itsfinal match. Therefore, wemust use seed.

COMPOST NEEDEDIN DIVOT MIX

The divot mix is 80%sand and 20% compost.

The compost is an absolute necessity to hold moisture for germi-nation because we are restricted to a very delicate watering regi-men (more on this later). We use an 80% Kentucky bluegrass and20% perennial ryegrass blend for the divot mix. The ryegrass ger-mination is critical to hold the divot together until the KBGcomes in. We always are experimenting to find the best methodsfor germination. In the heat of the summer, we began experi-menting with pre-germination. The methods were extremely sci-entific and calculated, meaning we threw the seed bags in a horsetrough full of water and poked holes in them, letting them soakfor a day. Did this help? I can’t tell you for sure, but I believe thatit worked to our benefit.

I plan on continuing pre-germination and comparing withother methods like using a pre-coated-seed for higher germinationrates. The best and most efficient process will never be found be-cause there always will be something new to try and see what hap-pens. Once the seed and sand are mixed we load it into a trailer.The trailer is pulled back and forth slowly with 8 to 10 divotfillers following, each with a bucket in hand. For the next 6 to 8hours, it’s scoop, drop, smooth and move until all of the divotsare filled. A final drag with a chain between two carts will helpclean up any sand piles and save the life of the reels for thenext mow.

Our watering situation is also very unique compared to mostturf properties, mostly because there is no in-ground irrigation onthe fields. We use large water reels, each 300 yards long. We alsohave water cannons outside the playing field that are spaced atevery 75 yards. The reels are pulled out with a tractor and reeled

Most of you haveprobably heard about thedivot stomp, where thespectators enter the fieldbetween chukkers andstomp down the divots.


in as the water pressure turns the turbine to move the gears. Imentioned before that we are on a very delicate irrigation regi-men. These fields have no drainage, and the reels, even at theirfastest rates, will put out enough water to replace the ET on a 90degree day, so it is impossible to throw a light syringe over theproperty to cool it down.

The moisture level in the soil directly affects the horses’ abil-ity to run, turn and stop. Too wet and the turf becomes too softand sloppy, too dry and the turf becomes too firm and slippery.There is a 4-to-6 hour window of optimal playing conditionswhere the irrigation has dried enough to play on and before thefields are too dry and firm. Timing is everything and adjustingto weather conditions is extremely important. For spot treatmentover such a large area the best option is to pull around aboveground lines with pods that hold the irrigation heads upright.This allows us to keep the moisture levels adequate and even dueto the inconsistencies of the fields. As if all that weren’t difficultenough, we share our pump station with the HOA and cannotwater at night due to pressure loss. The irrigation challenges areplentiful, but with a strong dedication to spot watering we havebeen able to keep a consistent playing surface and green grassthroughout this season.

These fields were not originally intended for professionalpolo. They had been aerated, but need more than a simple aera-tion twice a year. Compaction from polo requires increased cul-tivation. Using a verti-drain we were able to get down 8” on the1st attempt, 11” on the 2nd and 15” on the 3rd. Adding 3 coreaerations, 5 times slicing, 3 times verti-cutting for thatch re-moval, and adding over 2,000 tons of top-dressing sand, the turfand soil received a sigh of relief from 2 decades of compactionand thatch build up. These cultivation practices brought the sur-face firmness to an acceptable, and at a few times this season, anoptimal level for polo play.

The increased cultivation is a key factor in the level of im-provement that these fields experienced this year. Paying atten-tion to details that may have been overlooked before has createda more optimal growing environment for the turf. Adding prac-tices such as adjusting fertility based on soil tests, getting diseasediagnosis from extension labs and the introduction of wettingagents have all contributed to a very successful product for ourpolo team to play on.

My goal when I arrived here was to make our fields compara-ble with the world class facilities where the highest level of polois played. I believe at times during this season, we have achievedthat goal. With a little fine tuning, my goal now is to keep thoseconditions on a consistent level throughout the playing season.There will always be new methods to try, new innovations in ourindustry and more opportunities to learn from mistakes. Im-provement is always on the horizon, and perfection, althoughnever obtainable at its true definition, is the only acceptable out-come for the future. ■

Dave Radueg is Polo Fields Manager at the J-5 Equestrian Cen-ter, Littleton, CO.


MOST OF UShave managedan infield underless than perfect

conditions at one time or an-other. The infield may be inneed of reconstruction due toyears of use or it may have in-herent problems caused by im-proper construction. Whethersimply a facelift for an existinginfield, or the construction ofa new facility, a successfulproject requires considerationby those involved in the con-

struction process and bythose who manage the useof the field.

It’s natural to want the bestinfield you can have when theopportunity arises to renovateor construct an infield. Typi-cally, designers and engineerslook to construction practicesused on professional infields asa reference when designing forschools and municipalities.

For the sake of this article Iwould like to take the libertyof providing my perception of

a professional infield. A profes-sional infield is an infield con-structed on a full gravelblanket below a loamy sand orpure sand root zone. It has a½% slope radiating out in alldirections from the areaaround the pitcher’s mound.The skinned area is con-structed with two distinct lay-ers. The base is constructedusing an infield mix with lessthan 70% sand. This mix ismanaged at a precise moisturelevel to provide just the rightresilience to the players. Thebase is covered with a thinlayer of topdressing such ascalcined clay, vitrified clay orpossibly a mixture of both.The integrity of these layers isprotected with the utmostcare. For most of us, manag-ing a professional infield such

as this would be like CharlieDaniels playing Tchaikovsky’sViolin Concerto. Rather mostof us maintain infields in thegrey area of right and wrongsomewhere between a profes-sional infield and chase outthe cows close the gate andplay ball.

PERCEPTION IS NINETENTHS OF THE FLAW

I have witnessed municipalinfields constructed on a fullgravel blanket using heavy tex-tured impermeable top soiland a heavy clay infield mixbecause the perception is thatthis gravel blanket is going toprovide superior drainage forthe infield. These designersdon’t realize that unless theroot zone has a very high rateof hydraulic conductivity andis capable of allowing water topass through it efficiently, theonly real benefit to anysubsurface drainage is thecontrol of ground water or ahigh water table.

These same designers likethe ½% slope because; actuallyI don’t know why they use itother than because it’s used onprofessional infields. Whatthey fail to realize is that ½%slope is almost as ineffective asa gravel blanket in a turf areaunless again, you have a verypermeable root zone and some

>> BATTER BOARD was used todefine and elevate the infield arcto establish a diversion aroundthe infield.

Considerations in infield construction and renovation

>> Top Left: BASE PATH: Offsetfoul lines minimize lip buildup inthe grass adjacent to 1st and 3rdbase.

>> Middle Left: “WALK SOFT ANDCARRY A BIG RAKE.” Low groundpressure equipment was used toinstall the big roll bluegrass sod.

>> Bottom Left: RED SCREENINGSwere used to create wide pathsand minimize turf wear.

FieldScience | By Jim Hermann, CSFM

Some designers recommend a heavytextured clayey infield mix like XYZstadium, not understanding thatunless the moisture in that mix isimpeccably managed, it’s going toget hard as a rock.


form of subsurface drainage. On theskinned area, ½% slope is very difficult forthe average maintenance crew to manageeffectively and typically requires laser grad-ing a few times a year to remain effective.

Some designers recommend a heavy tex-tured clayey infield mix like XYZ stadium,not understanding that unless the moisturein that mix is impeccably managed, it’sgoing to get hard as a rock.

I witnessed a regulation little league in-field constructed with a conical grading plansimilar to the professional field I described.In this case the designer was sharp. He un-derstood that ½% slope isn’t sufficient. Hetherefore recommended a 1% slope radiat-ing out in all directions from a point cen-tered on the infield turf. What he failed torealize is that you cannot construct a regula-tion pitcher’s mound using this grading planand adhere to the requirement that thepitching rubber be 6” above home plate. Infact, there would be no mound at all. A 1%rise from home plate to a pitching rubber at

a distance of 46’ would be about 5.5”. Thiswould however be a very effective gradingplan for a softball infield with no mound.

This same consideration afforded to alittle league infield is necessary for a 90’baseball infield where the height of thepitching rubber is required to be 10” abovehome plate. In this situation you cannotconstruct a regulation mound using anymore than a ½ % slope from the pitcher’smound to home plate. Even at ½% slope,the mound would only be about 6” highallowing only enough elevation for a 6’landing zone in front of the rubber. In thissituation the desires of the coaches andathletic director need to be understood andthe requirements prioritized to allow for asuccessful project.

ST. ROSE HS GETS A NEW FIELDI had the opportunity to be involved in a

construction project at Saint Rose HighSchool in Belmar New Jersey. The loss of afacility they had used for years required the

school construct a new varsity baseball fieldat another site comprised primarily of soccerfields.

The project started with the inspectionof the new site and selection of the locationfor the new field. The proposed location wasin the corner of one of the existing soccerfields. The site was rectangular in shape witha diagonal slope of 1% across the entiretract. We had the option of selecting fromtwo potential locations for the constructionproject. We could use the upper cornerwhich would entail dealing with a diagonalcross slope away from the proposed homeplate or we could use the bottom cornerwhich would mean dealing with a 1% sloperight down the center line of the proposedinfield. Personally, I believe a cross slope isthe most difficult slope to deal with on aninfield. The excavation necessary to elimi-nate the cross slope was cost prohibitive soright or wrong we opted to deal with the1% slope down the centerline.

After the site selection, all those involved


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in the construction process were assembledto provide their particular expertise in theproject. Those involved were: thecoach/field maintenance supervisor; theathletic director; the landscape architect;and me, the consulting construction con-tractor.

For a few different reasons includingbudget, it was decided that an engineer wasnot required for the project and thecoach/field maintenance supervisor, MarkFletcher would be serving as general con-tractor on the job.

Based on the combined input fromMark and the athletic director, the architectdeveloped the footprint for the field, in-cluding dugouts, warning track, backstop,fencing etc. Mark and I took soil tests, eval-uated the existing topsoil and chose an in-field mix that was compatible with the levelof maintenance he would provide. The mixwas about 75% sand with about 1:1 silt toclay ratio. Tuckahoe Turf Farms in Ham-monton, NJ was chosen as supplier for thebluegrass sod we would be installing. Markalso lined up an irrigation contractor to in-stall the irrigation and quick connect be-hind the pitcher’s mound. A mason waschosen for the dugouts and the retainingwall. A fencing contractor would be in-stalling the backstop and perimeter fencing.

THE INFIELD GETS A PASSING GRADE

Literally every infield I have seen that isconstructed in the corner of a multipurposefacility has a problem with home platewashing out due to the prevailing slope. Forthis reason we decided to elevate homeplate 24” by means of a wall directly behindthe back stop. Along with this a diversionwas designed around the outfield radius ofthe proposed infield to divert the prevailingflow of surface water around the infield. Byelevating home plate 24” we were able tocreate a grading plan with a level center lineand approximately a 1% slope to 1st and3rd base that continued beyond the infield.I believe 1% to be the optimum slope for abaseball infield at this level of maintenanceand play. It’s enough slope to get the wateroff the infield turf when internal permeabil-ity of the root zone isn’t sufficient. 1%slope on the infield skin provides good sur-

>> Above left: CLAY BRICKS were installed in the pitcher’s mound and home plate. >> Above Right: 6” of topsoil was applied to all turf areas.

>> NO COWS on this infield.

>> A WALL was constructed to elevate home plate24” and create an acceptable grading plan.


face drainage, doesn’t require quite the pre-cision in maintenance a ½% slope requiresand 1% slope minimizes the potential forerosion associated with a steeper slope of1¼ to 1½%.

The elevation of home plate created aneed for about 500 cubic yards of fill mate-rial to raise the entire infield. Luckily theoriginal construction of the complex hadleft a mountain of material that wouldwork as an excellent fill material. The mate-rial was similar in texture to a sandy un-screened infield mix. I would compare it toselect fill which has a specified range of hy-draulic conductivity between 2” and 20”per hour. Select fill is a material sometimesused to help regulate percolation in a septicsystem. Because the topsoil we would beusing to cover the fill material was a heavytextured soil that was not very permeableand we all know that infield mix is not verypermeable, we decided subsurface drainagewould not be necessary. The only drainagepipe we installed was at the base of the walland we installed a sand slit drain around

the outfield radius of the infield to helpwith any water that might lay in the diver-sion. We did allow for channel drains to beinstalled in front of the dugouts at a laterdate if necessary. As with most any infield,we were relying on surface drainage to evac-uate surface water from the infield.

Once the grading plan and the archi-tect’s footprint for the facility were finalizedand documented, we were ready to begin

the project. Consideration on the part ofall involved in the construction project al-lowed for a successful project and the con-struction of a safe, durable and playablefield that is currently the pride of SaintRose High School. ■

Jim Hermann, CSFM is President of TotalControl Inc. Athletic Field Managementwww.totalcontrolinfields.com.

>> SINCE THE TOPSOIL would be reused, we stripped and removed the sod.


FieldScience | By Max Schlossberg, PhD, Joel Simmons

SOIL FERTILITY TESTING is a valuable agronomic toolcomposed of four steps; sampling, analysis, interpretation, andrecommendation. Sampling practice is standard boilerplate stuff.

Perhaps modified in regard to depth; e.g. by potential rooting depth ofspecies or need for subsoil investigation, sampling accuracy improveswith each additional sub-sample pooled from the area of interest.

The next stage is analysis, and “routine” soil fertility analysis affordslittle artistic liberty. Submitted soilsare dried and homogenized before anexact mass is mixed with an extrac-tion solution. Typically chosen on thebasis of regional parent material orsample soil pH, extraction solutionsinclude Mehlich-1, Bray P-1, Mor-gan, and Mehlich-3. Their purpose isto rapidly displace nutrients from soiland preserve them in their solubleforms, facilitating precise measure ofsolution nutrient concentrations bystate-of-the-art analytical equipment.Since a known volume of extractantis added to a known soil mass, each

resulting soil nutrient level (in parts per million, ppm) is derived pre-cisely from extractant concentration (mg/L).

Success through the first half of the soil fertility testing process re-lies on consistency, and this is something I believe we can all agreeupon. If only the second half were so easy.

Interpretation is simple characterization of soil pH and nutrientlevels by keywords like suboptimal, deficient, adequate, optimal,supra-optimal, and/or excessive. Dependable interpretation relates in-versely to the number of presumptions made in the process (fewerpresumptions = better interpretation).

The recommendation component communicates the rate and ap-plication frequency of the liming agent, amendment, and/or fertil-izer(s) required to achieve the turfgrass manager’s expectation, andmay be divided into pre-plant and annual maintenance sections. Thevalue of the recommendation depends on the provider’s interpretationof soil nutrient levels and familiarity with the growing environmentand maintenance level imposed. The best consultants base their rec-ommendations on soil nutrient levels, resident turfgrass species/culti-var(s) adaptation, irrigation water quality/quantity, soil pH, seasonalclimate patterns, and the client’s cultural practice “schedule.” Recom-mendations to engage in very specific fertilizer/amendment “pro-grams” composed of numerous products containing similar nutrientsshould be considered suspect.

SportsTurf’s Point–Counterpoint: SLAN vs. BCSR

Soil fertility interpretation: base saturation or sufficiency level?

>> Max Schlossberg, PhD

THE CONTROVERSY over the use of the base satura-tion ratio (BCSR) versus the sufficiency levels of avail-able nutrients method (SLAN) has perpetuated for

many years now and with very little change in either side’sthinking. The reality is that base saturation is one tool of manythat most independent agronomists use to help their clients be-come more successful. The other important reality is that most

of us using the BCSR methodalso look very closely at thesufficiency levels of nutrientsstudying both standard col-loidal soil test audits and watersoluble paste extracts.

For 25 years I have been astrong advocate of the BCSRmodel and have heard every-thing from “it’s wrong” to“he’s going to ruin golfcourses.” A university agrono-mist recently said to me “Wedon’t agree with the BCSRmethod but we know that

most independent consultants use this tool.” That spoke vol-umes, if it was in fact wrong or going to ruin golf courses wewouldn’t be using it because our clients wouldn’t pay us tocome back. There are strengths and weaknesses to all modelswhich is why using a broad spectrum approach to managingsoil and building fertility programs is critical.

Base saturation measures the percentage of the cations onthe soil colloid. Based on the extensive works of many peo-ple, most notably Dr. William Albrecht from the Universityof Missouri, the ideal cation percentages are 68% calcium,12% magnesium, 5% potassium, 3% trace nutrients, 2 %sodium and 10% hydrogen. These ideals are never found inpractice and are simply a guideline to start from. This modelis not a great tool in sand-based low CEC soils or calcareoussoils as compared to clay/silt based soils so we compensate inthese situations and lean much more on the sufficiency mod-els. However since most soils that we do evaluate are true soilprofiles the BCSR model is a good tool to start with and pro-vides us with much information as to the nature of the soil.

Perhaps the greatest value that those of us that lean on thebase saturation tool gain is the one that tends to generate themost passionate debate. Base saturation helps us primarilywith the physical properties of the soil, as we move a soil into

The base saturation tool inturf management

>> Joel Simmons


The question of how soil nutrient levels are used to recommendfertilizer/amendment applications to a turfgrass-environment-cul-ture system is typically answered by one, or both, of the predomi-nant methodologies; the base cation saturation ratio(BCSR) orsufficiency level of available nutrients (SLAN). Brief and objectivesummaries of each method follow (in no particular order).

The BCSR concept, developed by F.E. Bear and colleagues in1945, supports maintenance of an “ideal” soil having: 65% of cationexchange sites occupied by calcium (Ca) charge, 10% by magne-sium (Mg) charge, 5% by potassium (K) charge, and 20% by hydro-gen (H) charge. Thirty years later, “The Albrecht Papers” definedthe ideal BCSR as 10% H, 10–20% Mg, 2–5% K, 60–75% Ca,0.5–5% Na, and 5% other cations. In support of plant productivityand health, BCSR embraces balanced availability of base-cation nu-trients in soil. The SLAN concept, introduced by Mitscherlich in1909 and further-developed by Bray in 1945, supports comprehen-sive maintenance of nutrient levels (i.e., thresholds) on a soil massbasis. The SLAN method seeks to rectify nutrient deficiencies thatwould otherwise limit productivity and health (yield). Discussionsrelating each concept to justifiable attributes follow.

SIMPLICITYRemember: the less presumed, the better the result. Interpreta-

tion by BCSR requires conversion of soil nutrient mass to nutrientcharge concentration, and presumes divalent cations of interest

a range of “balance” we have repeatedly seen the soil open upphysically allowing more water and air movement through thesoil profile. We are not changing clay into sand, we are not mak-ing silt into clay, but are flocculating the soil just enough to relaxthe soil colloids to create the tiniest of pore spaces to allow air toflow through the soil a little more freely. The range that we arelooking for from on a true base saturation test puts calcium intothe 60-70 percentile, magnesium down to the 12-18 percentile,keeping potassium close to 5% and holding hydrogen levels toaround 10%. On a true base saturation soil test when hydrogenis at 10%, the soil pH is always at 6.3 which is generally recog-nized as the point at which we have maximum potential nutrientmobility.

Unfortunately, many laboratories do not run what we calltrue base saturation soil tests; they may show only the percentageof calcium, magnesium and potassium. Some very popular labsrun reports that have pH readings in the low 6 range, whichclearly suggests that there is close to 10% hydrogen on the soilcolloid. Since pH measures the acidity of the soil, or in layman’sterms the percentage of hydrogen, when the soil pH is below 7.0we know that hydrogen is on the soil colloid. Too often the soilreport does not show a hydrogen percentage or for that mattershow the percentage of either the trace elements or sodiumwhich in combination could add up to over 15% of the colloidalmakeup when the soil pH is in the low 6 range.


FieldScience

The other truth of base saturation is that it is a percentage so italways has to add up to 100%, not more and not less as manylabs report, so it is easy to see the concern about using this toolwhen it is not a true percentage. I have heard an industry leadersay to a group of turf managers that he can tell the base saturationby looking at the pH which was truly baffling. A soil pH can bedriven by many different cations on the soil colloid and under-standing their relationships to each other and reducing the ex-cesses by supplying the deficiencies we have repeatedly and withgreat consistency brought the soil into balance. This in turnopens the soil up physically and provides a better environment forthe proliferation of beneficial micro-organisms.

“SELLING” POINT?My favorite criticism of the base saturation model is that it is

used exclusively to sell more fertilizers when in fact the exact op-

(Ca+2 and Mg+2) each occupy two soil exchange sites. However,modern solution chemistry models show this dependability dimin-ishes with increasing alkalinity of soil. The SLAN approach inter-prets the soil nutrient mass as is (ppm soil), and simplyrecommends nutrient delivery equal to the difference between thecurrent nutrient level and the field-calibrated deficiency threshold.

SCALABILITYThe SLAN concept offers interpretational flexibility both prac-

tically and agronomically, specifically in regards to yield expecta-tion, sampling depth, and extractant. Examples of SLAN sensitivityto yield expectation are the widely—adopted Mehlich-3 soil K de-ficiency thresholds of: 232 lbs/acre in intensively—maintainedrecreational turf systems, and 167 lbs K/acre for general use turfunder limited culture. A logical approach considering support ofturf vigor and recuperative potential requires more growth-stimu-lating inputs (e.g., culture, N, irrigation) than general use turf sys-tems. Consequently, increased K-sufficient tissue off take results ingreater seasonal K uptake/requirement. The likelihood of clippingremoval from the former system, and return of clippings to the lat-ter further validates the intuitive scalability of SLAN.

Similarly, a sampling depth example involves a recreational turf-grass target of 250 lbs soil K per acre (from above SLAN-basedMehlich-3 recommendation). Since a 6-inch deep acre of soil typi-cally weighs 2 million pounds dry, this target equates to 125 ppm

A soil pH can be driven by many differentcations on the soil colloid and understandingtheir relationships to each other and reducingthe excesses by supplying the deficiencieswe have repeatedly and with great consis-tency brought the soil into balance.


FieldScience

K in soil sampled from 0-6 inches. I understand managers of sand-based football fields are investigating lower mowing heights to pro-mote “shallow” root density and enhance divot resistance andstability of the playing surface. A clever tactic given lower mowingheights (within recommended ranges for a turfgrass species) corre-late to lesser mean rooting depths (all other things equal), but notless total roots! Like many superintendents managing annual blue-grass putting greens, these athletic field managers may constrain fer-tility assessment to the upper 4” of soil. But how can SLAN cope?Easily, the recreational turfgrass target of 250 lbs K/acre translates to188 ppm K in 0-4” of soil. Thus, if analysis shows exchangeable Kof 150 ppm soil, then optimal K fertility will require a 38 ppm soilK increase. The 0-4” deep acre root zone weighs 1.33 millionpounds, thus a rectifying application of 51 lbs K (61 lbs K2O) peracre is recommended.

To these scenarios application of BCSR theory generates an iden-tical recommendation, hardly as intuitive or meaningful as thoseshown.

SUITABILITYBCSR-derived recommendations typically fail to optimize K

availability in soils having limited cation exchange capacity (CEC).Considering SLAN effectively interprets fertility over a wide rangeof soils, suitability serves as yet another harbinger of doom for theBCSR–turfgrass relationship. For example, a 6” sand rootzone sam-

posite is true. When the soil opens up physically and more airand water is moving through the soil biology is more active andthe nitrification processes work better. We consistently see ath-letic field managers using less fertilizer and getting better vigor,color and recovery. The one input that we may shift for a yearor two is the use of calcium products, if the soil test calls forthat, as we bring the base saturation of calcium up to the 60percentile mark. This may be the least expensive input in anyprogram but the impact is significant. The calcium products arenot exclusively designed to feed the plant but instead are usedto flocculate the soil, opening it physically, and helping to stim-ulate soil biology which will in turn puts the plant into a posi-tion where nutrient mobility is improved.

Once the soil is balanced chemically to allow for a betterphysical and biological profile the entire focus is sufficiencylevels of nutrients so that we can assure that the plant is get-ting all that it needs especially at high stress times on the ath-letic fields. This approach makes sense, it addresses both thesoil needs and the plant needs not just the latter. It has beenproven in the field for years, over and over again, helping turfmanagers become more successful with less, reducing plantstress. This reduces the need for many inputs including fertil-izers and pest control products.

The bottom line is if using base saturation models as a tooltruly did not work, sports turf managers would not use it a


ple extracted by Mehlich-3 to show both the ‘ideal’ base cationsaturation (5% K) and a CEC of 2 cmol/kg contains approximately78 lbs exchangeable K/acre. While BCSR is considered a “relativelysuitable” calibration technique in fields comprised of high-CEC soil,our greatest challenges currently relate to effective and efficient nu-trition of sand-based (low-CEC) turfgrass systems.

In summary, the SLAN (sufficiency level of available nutrients)approach is your boy for effective interpretation of turfgrasssand/soil fertility and responsible fertilizer recommendation. Thereis no debate regarding claims of soil physical property enhancementvia BCSR recommendations. Of all the techniques available formaintaining porosity in highly-trafficked mineral soils, none invokesmore laughter among turfgrass scientists than the “fertilizing to ob-tain a balanced base saturation” approach.

Why not both SLAN and BCSR together? Because there are al-ready too many unimaginative fence-sitters proclaiming hybrid har-mony. Furthermore, the hybrid model deviates from the conceptsoriginally proposed! The above-mentioned scientists, who spentsignificant portions of (if not all) their careers developing thesemutually exclusive methods, just wouldn’t approve. Besides, do youknow how labs using BCSR for Ca, Mg, and K make P recommen-dations? SLAN . . . because it works. ■

Max Schlossberg, PhD, is associate professor, turfgrass nutrition &soil fertility, for Penn State’s Center for Turfgrass Science.

second time because they are responsible and understandtheir needs to produce a quality product every single day.As we have been focusing on in our “Soil Profile” series inSportsTurf, like the Wellesley article featuring the successesof turf manager John Ponti, base saturation a good tool tostart with to help create the environment for a strongerchemical, physical and ultimately biological profile to helpbetter mobilize nutrients that do become available to theplant. So with this level of success and a thorough programthat does focus on both BCSR and SLAN, where is thecontroversy? ■

Joel Simmons is president of EarthWorks Natural OrganicProducts and Soil First Consulting. He has a master’s degreefrom Penn State, is a former PSU extension agent, and formersoils instructor for Rutgers University.

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