inches will result in a depth of 24 to 30inches at the point where the line enters themain line to the outlet. The drain lines areinstalled at a 0.5 to 1.0% grade (0.5 feetfall/lOO feet of run). Remember there is a0.33% grade in 100ftofa 4-inch tube itselfif it were installed perfectly level.It is not necessary to place stone below

the tile line, unless the stone is used toobtain a uniform grade on the line wheninstalled with a backhoe. Likewise it is notnecessary to enclose the line in geotechnicmaterial unless the native soil is a very finesandy loam or a silt. Many installations aremade with a backhoe which does not pro-vide the grade control obtainable with thelaser- controlled excavating wheel or chainused on commercial tile laying machines.The use of a laser-controlled tile layingmachine is not only more accurate, butfaster, and worthy of serious considerationby the contractor.

The tile lines should be installed after thesubgrade has been. graded to the desiredslope of the surface of the field. Installingthe lines under wet conditions can destroythe smooth subgrade by leaving ruts, thuspreventing the free movement of water lat-erally to the tile lines in the future. Regrad-ing of a disturbed surface may be difficultas the graded material cannot be spilledonto the tile lines. Crushing of the lines canoccur if heavy machinery is used overfreshly laid lines, therefore care must beexercised in movement of the remainingmaterials into place by restricting truckmovement and plank bridging over thelines.

Category I fields require the placement ofa 6-inch depth of stone above the tile andover the entire subgrade surface (Fig 1).The selection of the size of the stone iscritical because the migration of the finermaterials used in the rooting zone into thestone blanket must be avoided if the drain-age system is to function properly for dec-ades.

USGA specifications call for a stone layerhaving 65% ofthe stone in the range of 1/4to 3/8 inch, with not more than 10% greaterthan 1/2 inch, and not more than 10%below1/10 inch. The stone layer is then coveredwith a 3-inch layer of course sand (chokerlayer) to provide the necessary bridgingover the large pores in the stone. Installa-

UNDERSTANDING TURF MANAGEMENT

BUILDING THE SPORTS FIELD

Municipal governments, school..boards and service clubs are prone

to allocating money for the construction ofa new sports fields with minimal investiga-tion of field requirements. Often thequestions which are asked by the authori-ties are "What type of construction shouldwe use?", "What should we be specifyingin the tender?"

The cart is now before the horse! Thequestions which should have been askedfirst are: "What is the level of expectationof the field?", "What are the managementrequirements for maintaining the field -labour, equipment, irrigation, on-goingfunding?" Then the funding should be allo-cated.

Any funding organization contemplatingthe construction of a new sports fieldshould begin their discussion with the firstof the above questions because the level offunding for both construction and mainte-nance depends on the 'level of expectationof the field', not the sport which will usethe field - soccer, football, field hockey, etc.

The 'level of expectation' of the field maybe divided into three categories. The high-est category - Category I fields - are themost expensive to construct and maintain.They are the fields where professional orsemi-professional league and tournamentplay will take place. An infrastructure ofstands, change rooms, lights, etc., are in-cluded in the budget, and often cost morethan the actual field. A further criteria forthis category is that pre-game seat sales willoccur, thus a cancellation of a game is notan acceptable alternative. This categorycalls for the construction to follow theUnited States Golf Association GreensCommittee (lJSGA) specifications forgreens construction. Category I fieldsshould never be attempted without a guar-anteed, uninterrupted water supply.

The lowest category - Category III fields- are the local neighbourhood facilities forminor league play and unscheduled play bythe general public. No change rooms,stands or other facilities are available andminimum security fencing is provided toinsure the play does not spill over intoadjacent streets. The quality of the turfshould be such that good ground cover ismaintained to insure the safety of the user.

The middle category - Category II fields

The 15th in a series byR.W. Sheard, P.Ag.

- are the most difficult to define, and alsoto design. They may be considered as fieldswhere play is generally scheduled, but maybe cancelled due to field or weather condi-tions and where limited infrastructure in theform of change rooms and stands are pro-vided. Even so, the quality of turf should behigh and the construction such that heavyuse may be entertained.The Drainage System

The first requirement of a field in any ofthe three categories should be to assure thatadequate surface drainage is available.While mandatory for Category I and ITfields which, during construction, will begraded to a defined slope or crown, Cate-gory III fields often accept the natural gradeor slope of the site. Such acceptance in tumleads to future problems where low areaspond water, increasing the potential dam-age to the turf. Extra funding to insure aproper surface grade prior to seeding thefield will result in lower maintenance costsin the future.

The design of all sports fields of CategoryI and II must begin with an adequate sub-surface drainage system in addition to sur-face drainage. The first step in designingthe drainage system should be a satisfac-tory outlet for any drainage water. The out-let most probably will be the storm waterdrainage system.

Drains are 4-inch, perforated, plastic tubespaced at least every 40 feet apart, but inimpervious clay soils or sand based rootingzones they should not be more than 20 feetapart. Due to the low cost relative to otheritems in the construction of a field it is oftenadvisable to space the lines 20 feet apart, orless, under all soil conditions.

Some installers prefer to use a herring-bone design. The design adds nothing to theefficiency of the system and may contributeslightly to the cost. The simplest and mostefficient system from the installers view-point are lines running the length of thefield: commencing at mid-field, with a fall-ing grade, to extend at least 20 feet beyondthe playing surface at the end of the field.An additional line outside the playing sur-face for the players bench area is oftenadvisable.

Tile lines should be installed at a mini-mum depth of 18 inches below finishedsurface grade. A mid-field depth of 18

Fig. 1: A cross section of a sand-based rooting zone forturf. .

Sand: Soli: a.M.mix

SandOR

Sand: Soil: O.M.mix

1.0to 1.6mm Sand(choker layer)

0.6 to 1.0cm GRAVEL

7.6cm PERFORATEDPLASTIC AT

6 METER SPACINGSUB·GRADE MATERIAL

Fig. 2: The envelope for the particle size distribution of the stonelayer without a choker layer of sand.

tion of the choker layer is a slow, labour intensive operation.An alternative now accepted by USGA is to use a smaller stone

without the choker layer. For bridging of the root zone particlesover the pores in the stone layer to occur the D15 (diam. belowwhich 15% ofthe stone particles lie) ofthe stone must be less thanor equal to five times the D85 (diam. below which 85% ofthe sandparticles lie) of the root zone mix. Likewise for adequate perme-ability of water to occur the D 15 of the stone must be greater thanor equal to five time the D 15of the root zone mix. Finally the stoneshould have a gradation index (D9O'D15) less than or equal to 2.5.It is preferable that the stone be an angular shape, suggestingwell-screened, crushed aggregate. An example of the size envelopeof a satisfactory material is provided in Figure 2.The Rooting Zone

The next step in the process of construction of Category I and IIfields is the selection of the rooting zone mix. Whatever materialis used, the rooting zone should be a minimum of 12 inches in depth(Fig 1). The same care must be exercised in placing the root zonematerial over the stone as was used in putting the stone in place,otherwise rutting and intermixing with the stone will occur.

Many Category II fields are constructed using the native soil forthe rooting zone. Prior to approving a native soil foruse it shouldbe subjected to particle size analysis and moisture transmissionanalysis. The textural class of the soil should be a/course sandyloam or loamy sand and should have less than a total of 10% silt

plus clay. Silt loams and clays should be avoided. It should havethe ability to transmit a minimum of six inches of water per hour.

The heavier textured soils may be modified by the addition ofsand using the monogram in Figure 3 to select the amount of sandto add. A well-aggregated, screened, surface soil should be selectedand thoroughly mixed off site with the sand. Careful costing of thesand modification alternative, relative to other options, should bedone because if an incorrect blend of sand and soil is selected thisprocedure may resulted in a very poorly draining, compactedsystems.

The rooting zone of all Category I fields should be based on theprinciples of USGA greens construction. The principles involvethe construction of a tile and stone blanket drainage system onwhich is placed a special root zone mix. The mix comprises aselected sand to which a relatively small amount of soil and/ororganic material is added. The resulting mixture will not be subjectto future compaction and will have water transmission valueswhich will permit play under all weather conditions while mini-mizing the damage to the grass.

The selection of the sand for the root zone is critical. Theprocedures to follow are outlined below.

Several potential suppliers of sand should be selected and askedto submit a two kilogram sample for particle size analysis. Thesuppliers should be asked to supply a brick sand or topdressingsand, because these are the trade names for materials which willmost probably fit the USGA requirements. The samples should besent to a laboratory capable of performing sieve analysis of sandand characterizing the moisture relationships of the final mix.

Suitable sands should be selected on the basis of a particle sizedistribution which falls within the envelope illustrated in Figure 4.Care should be taken to select a sand that is very low in silt andclay size particles (less than or equal to 0.05 mm) because uponthe addition of the soil material the final mix must not exceed atotal of 8% silt plus clay. Having two or more samples which meetthese criteria the contractor is in. a position to negotiate price,supply, delivery, etc., with the suppliers.

The next or concurrent step is the selection of a suitable top soilto add to the sand. The preferred soil should be a screened materialcontaining no stones or other debris, weed free, herbicide free, havea high organic matter content and have a sandy loam texture.Samples from potential sources should be subjected to particle sizeanalysis for percent sand, silt and clay by hydrometer analysis,percent organic matter and percent total carbonates. Samples con-taining less than two percent organic matter and/or more than 10%carbonates will suggest contamination with significant amounts ofsubsoil.

In many areas a sandy loam soil does not exist. In these cases thelocal loam or clay loam soils may be used, but the amount whichmay be added to satisfy the 8% total silt plus clay limitation willbe sharply reduced.

Based on the silt and clay analysis of the soil material a calcula-tion is made of the amount of soil which may be added on a volumebasis to the sand. A small sample mix is prepared. Organic mate-rials such as peat moss, compost or other organic wastes may thenbe added. These organic materials should not exceed 10% byvolume of the mix. The organic material chosen should also havea loss-on-ignition value in excess of 85% because some organicsources can contribute significant silt and clay to the final mix.

Having prepared the sample root zone mix it is again subjectedto screen analysis to confirm the mix still fits within the particlesize envelope (Fig. 4). It is recommended that the soil material bevery finely ground or physically dispersed in Calgon solution,dried and ground again before adding to the sample mix for sieve

analysis. This step is necessary where well-aggregated, high claycontent soils are used because the small aggregates of soil will sieveout as sand.

Having satisfied the criteria of particle size by relatively inexpen-sive sieve analysis the final selection step is to conduct the rela-tively expensive porosity and moisture characterization of thesample mix. The accepted range of values are listed in Table 1.

In most circumstances if the selection based on particle sizeanalysis has been performed correctly and the criteria for particlesize adhered to, the physical properties will fall within the acceptedrange. If, however, the sample mix fails to pass the one or more ofthese physical properties it is advisable to re-examine the mixselected.Installing the Rooting Zone

Pre-mixing the sand, soil and organic material off-site is anabsolute necessity to insure proper blending of the ingredients. Itis not necessary to screen the top soil below one inch as the larger

Table 1: The physical properties of a suitable root zone mix.

Criteria RecommendedRangeTotal Porosity 35% - 55%Air-filled Porosity (@ 40 cm tension) 20% - 30%Capillary Porosity (@ 40 cm tension) 15% - 25%Saturated Hydraulic Conductivity 15 - 30 cm/hrMoisture Retention (@ 30 cm tension) 2.5+ cm/30 cm depth

Fig. 3: A monogram for estimating the volume of sand to add to asoil:organic matter mix to provide a suitable rooting zone material.

100.-------------------------.

95

90C)

.:.::0 850T""

"0 80.:.::C 754l '" #1 loamy sand soilC

70 o #2 sandy loam soil0() o #3 loam soil"CC 65 ... #4 clay loam soil~

60• #5 sih loam soil

• #6 sihy clay soil

55

501 2 3 4 5 6 7 8 9 10 11 12

Volume of sand added to 1 soli and 1 peat

Fig. 4: The envelope of the particle size distribution of the sand forthe rooting zone mix.

aggregates act as islands of soil in the sand matrix. Mixing may beadequately performed by front end loaders; adding the materials inthe desired ratio by volume of the bucket. Mixing is accomplishedby repiling the mix several times. Peat should be moist during themixing stage to ensure uniform mixing and to minimize peat andsand separation.It is also a good practice to add 1.5 pounds of phosphate fertilizer

(0-46-0) and 0.3 pounds of potassium fertilizer (0-0-60) per cubicyard of mix.

Depending on the economics of the particular site the sand:soilmix may be used throughout the entire 12 inches of rooting zoneor restricted to the upper four inches. The shallower depth ofsand: soil mix, however, may be more expensive due to the need toinstall two lifts of material. Of course the bottom lift would be thesame sand as was used in making the sand:soil mix. It would notbe necessary to add organic material to the lower layer.

Sand which is dry has a very low bearing capacity for equipmentwhereas sand which is wet will carry substantial loads. It is there-fore an essential practice to have an irrigation system installed ora portable system working so that the sand is kept wet at all times.It also aids in preventing wind drift of the sand.

The sand-soil mix is dumped at the edge of the field and bladedinto rough position with a small bulldozer. Final surface gradingmay be accomplished with a motor grader. Moving loaded trucksonto the field can result in rutting the gravel layer and intermixing,particularly by unloaded trucks starting up to move off the fieldafter dumping their load.It is a good practice to have a vertical division between the

adjacent soil material at the edge of the field and the sand root zonemix. The sharp break between the two types of material avoidsmoisture related growth problems in the future. Strips of plywoodor heavy plastic may be used, and moved as the installationprogresses .

Sodding, hydro seeding or standard seeding methods may be usedto establish the turf. It is essential that the irrigation system befunctional before turf establishment is attempted. A standard fer-tilizer program for turf establishment should be followed.

A quality control program during construction is strongly recom-mended. Periodic, on-site sieve analysis of the sand as it is deliv-ered will insure that the sand conforms to that used in the laboratoryanalysis and that the field will perform as desired.

Finally, it must be emphasized that Category I fields require ahigh level of management skills. Some people have regarded thesefields as a large hydroponics system. This may be an exaggeration,nevertheless, the field manager must be very conversant with plantnutrition and water use because the normal buffering - ability toresist change - of soils is missing. A delay of two days in irrigationor postponing a fertilizer application for a week can result in aninferior playing surface.

ANALYTICAL LABORATORIES - SOIL PHYSICAL ANALYSISStandard Soil Consultants, Inc.,2181 Rue de la PlantationSt. Lazare, POJOP 1VO(514) 455-7645

Analytical Services,Dept. Land Resource Science,Univ. of Guelph,Guelph, ON. N1G 2W1Attn: Virginia Marcille-Kerslake(519) 824-4120

Agri-Systems of Texas Inc.15511 Baldswelle,Tomball, TX.U.S.A. 77375Attn: Judith Ferguson Gockel(713) 376-4412

Colorado Analytical Lab.,P.O. Drawer 507240 South Main Street,

~~~~~n8~~1Attn: Shane Nielson (913) 829-8873

Brookside Farm Labs. Inc.,308 South Main Street,New Knoxville, OH.U.S.A. 45871Attn: Mark Flock(419) 753-2448

Int. Sports Turf Research Center,1530 Kansas City Road, Suite 120,Olathe, KS.U.S.A. 66061Attn: Leon Howard(303) 659-2313