Spring Topdressing and Seeding:

Spreading Success

Topdressing programs must becustom-tailored to meet site-specificneeds. Variables include field soiltype, topdressing mix, weather,timing and application rate,irrigation, equipment, and more.

T ^ hey seem like suchm simple processes —

m spring seeding andtopdressing — but often theymake the crucial difference inwhen an athletic field willbecome playable after winter.They work in tandem and shouldbe thought of, in terms of tim-ing and application rates,accordingly.

There is no single topdressing/seed-ing formula that works in all situations.Your particular strategy will hinge on anumber of variables including turf type,soil type, climate, play schedule, irrigation,and much, much more. Still there aresome fundamentals to keep in mind,and here's what the experts have tosay.

20 sportsTURF

Build On BasicsMonty MontagueTurfco Manufacturing, Inc.Consider the objectives of a top-

dressing program in terms of the exist-ing conditions of the field or fields in ques-tion, and the goals you wish to achieve.Conditions requiring topdressing willvary with the individual field. Topdressingwill benefit turf on a compacted and/or

difficult-to-manage soil. It can helpamend or augment the soil profile fol-lowing aeration or modify the surface layerof soil. It can be used in rebuilding ormaintaining the crown of a field, or tosmooth an uneven playing surface.Topdressing used properly:

•Protects the crown and lateral rootsand shoots of turfgrasses from wear

continued on page 22

Spring Topdressingcontinued from page 20

and the elements.•Helps reduce thatch buildup to

ensure proper infiltration of water andfertilizers.

•Helps maintain moisture levels.•Improves the rooting of stolons.•Protects and insulates germinat-

ing seed and seedlings from excess heatand traffic injury.

An effective topdressing programrequires light applications of material atfrequent intervals, so that there's nodevelopment of layers, either of top-dressing material or thatch. Proper top-dressing will provide an excellent soil onwhich to maintain the field in the future.

Many errors in topdressing have a min-imal short-term detrimental effect, buttend to have the greatest detrimentalimpact in the long-run.

Most sports turf managers topdresstwice a year, in the spring and fall, fol-lowing core aerification. Using a lightapplication more frequently can be evenmore beneficial. Lighter topdressingapplications can be made as frequentlyas once a month, depending on the fieldneeds, turf type and condition, and themakeup of the topdressing mix.

Though topdressing offers many ben-efits, they must be balanced by theunderstanding of soil and topdressing com-patibility. If the existing soil drainspoorly and compacts easily, you maynot want to topdress with the same soil,even though it would provide the great-est compatibility.

The same level of care when selectingand mixing materials during construc-tion should be applied to the selectionand use of topdressing materials. Talkto your local agronomist or consultant todetermine the correct topdressing mix foryour field needs. Don't just add somethingto the mix because you've heard it mightbe beneficial.

PrecautionsUsing a topdressing with a texture dif-

ferent than that of the existing soil car-ries a risk of layering. A surface layer canimpede the movement of air, water, andnutrients in the rootzone.

Layering has been cited for disrupt-ing decomposition processes in moistsoil by creating anaerobic conditions,which result in black layer and other sub-surface problems. Surface water perco-lates down through a layer of well-tex-tured surface soil to the heavier soil

Topdressing can helpamend or augment

the soil profilefollowing aeration ormodify the surface

layer of soil.

below. The sub-soil becomes water-logged, robbing bacteria and microor-ganisms of the air they need to proper-ly decompose organic materials.

One way to avoid this problem is to aer-ify and then fill the holes created byaerification with topdressing material.

Soil/Sand Mixture ConsiderationsThere's a preference to use sand, or

a sand/soil-based mix for topdressing. Soil-based mixes may provide a better envi-ronment for maintaining adequate lev-els of desirable soil microorganisms, aswell as water and nutrient relation-ships.

The makeup of soil/sand mixturescan only be identified after the sandcontent of the soil is identified. First, deter-mine the sand content of the soil portionof the mix. Then the sand content ofthe entire blend can be determined byincluding the sand content of the soil withthe sand that will be added to the soil.An appropriate mix might contain 80 to90 percent or more of sand, even thoughthe mix makeup is 70 percent soil and30 percent sand. The additional sandwould already be present in the soilitself.

The critical components of a soil-based mix are silt and clay. Researchshows that approximately 10 percent silt,5 percent clay is appropriate; that is, siltequals 10 percent and clay equals 5percent of the total mix, which is a 2:1ratio of silt to clay.

Even when standards have been setfor the optimum topdressing mix foryour field, test the mix prior to appli-cations to ensure consistency amongbatches.

Sand QualityMost agronomists prefer sand in the

medium range. About 60 to 75 percentof the sand should be in the range of0.25mm to 0.75mm. Coarser sand (1.0mm)

should be kept to a minimum. No morethan 3 percent of the sand should be inthe very fine range (0.05mm-0.10mm).

Generally speaking, the narrowerthe particle size range, the more porespaces will be retained by the soil, andsusceptibility to compaction will belower. A sand with nearly equal per-centages of each of the sand size rangeswill be highly susceptible to compaction.

Sands with high silica content are pre-ferred because they are hard and resis-tant to the effects of weathering. If pos-sible, avoid using sands that have anappreciable amount of limestone-basedmaterials because of the probability ofpH problems.

Consider the particle shape of thesand (sharpness of grains).

Have the sand tested for pH, freecarbonates, nutrients (including trace ele-ments) and for the presence of soluble saltsand other undesirable components beforeyou buy or use it. Be sure the sand ven-dor can consistently provide the same sizeand quality of sand over the long-term.Keep in mind that sand used in top-dressing should always be washed.

Straight sand as topdressing canchange the existing water and nutri-ent maintenance schedule. Sand rootzones require careful management andclose watch on water. A good irrigationsystem is critical for sand-based ath-letic fields.

Topdress For SuccessThere are four prerequisites for an

effective topdressing program:1. Selection of quality sand or mix.2. Application at the proper rate.3. Application at the proper inter-

val.4. Evaluation of results, with adjust-

ments as necessary.The rate of topdressing application is

determined by the time of year, tem-perature levels, and how quickly thematerial will be dragged into the field.For frequent, light topdressing, ratesshould range from 1/32- to 1/8-inch. It isnot usually necessary to drag in these lightapplications.

After core aeration, a topdressingrate of 1/2- to 3/4-inch may be appropriate,depending on the size of the coresremoved and the number of holes createdby the process.

When topdressing to raise the level oia section of the field, the process shouldconsist of several light applications over

continued on page *°

22 sportsTURF

Spring Topdressingcontinued from page 22

a prolonged period. For example, a two-inch adjustment might best be handledover a two-year period, with no singleapplication made at a rate at above 1/2-inch.

Topdressing success depends largelyon the ability to control the amount of theapplication. Uniformity of application,accuracy, and reliability must all beconsidered when choosing topdressingequipment.

Sports turf managers should takecore samples of topdressed areas regu-larly to check root growth, moisture,and compatibility.

The Bear FactsKen Mrock, Chief GroundskeeperChicago BearsThe winter of 1993-1994 has been

hard on turf. Many cool season grass fieldshave faced extreme cold temperatures anddrying winds, long periods of ice and snowcover, or both during alternating periods.Some fields entered the winter alreadystressed from overly wet or overly dry con-ditions. To minimize damage and createsafe, playable conditions as quickly as pos-sible, spring preparations will need tobegin as soon as turf starts to breakwinter dormancy.

As soon as the soil is workable, coreaerify at least two directions to relievecompaction.

If the field's existing soil structure isacceptable, the best seedbed and top-dressing material is the same soil. Allowthe cores to dry, then use a woven men-tal drag mat to drag them back in andprovide a suitable seed bed. Any thatchdebris should be removed from the field.

Pregerminating seed can speed thespring seeding process. For Halas Hall,the Chicago Bears practice facility, wepregerminate a 50:50 mixture of bluegrassand perennial ryegrass in 55-gallondrums. The drums are filled with warmwater to which one-half to one pint of high-phosphorous liquid fertilizer has beenadded. The water is changed every dayfor five days. The barrels are drained onthe sixth day and the seed is spreadout to dry on a clean, concrete surface.We use the floor of the garage or, if con-ditions are favorable, the concrete apronadjacent to the garage. Drying time willdepend on temperatures and humiditylevels. With ideal outdoor conditions,the seed will dry sufficiently within one-half hour. Indoor drying will take longer.

Proper topdressingwill provide an

excellent soil onwhich to maintain

the fieldin the future.

Once the pregerminated seed hasbeen dried adequately, we add a smallamount of our standard topdressingmix of calcined clay, shredded peat,sand and native soil to make uniformapplication easier.

If you decide to incorporate pregermi-nated seed into your spring seeding pro-gram, the next step is to broadcast thepregerminated seed and topdressingcombination into any sparse areas ofthe field.

Follow this with applications of unger-minated seed in your preferred seedmix. Depending on the existing fieldconditions and the state of your turfentering the winter season, it may be bestto increase your standard seeding rate.For example, we'll increase our seedingrate by one to two pounds per 1,000square feet this spring to counteractdamage to the existing turf caused by lastfall's prolonged wet conditions. Where pos-sible, use a slit seeder and sow the seedmix in two directions.

Next, apply a starter fertilizer with ahigh phosphorous content to promote seeddevelopment. We prefer to use a fertil-izer formula that also has a relatively highnitrogen content to stimulate growthof the existing turfgrass.

As a precaution against pythium(damping-off), consider applying a pythi-um control product. Treatment for snowmold may also be necessary.

Our seeding process concludes witha light topdressing of our standard top-dressing mixture on any areas thatshow winter desiccation. Because weuse lightweight, perforated poly coversto protect the entire seeded area, this isall the topdressing that is needed. Thecovers act as a greenhouse to speed ger-mination and seed establishment, keepthe seed in place, protect the seed andyoung seedlings from washing out inheavy rains, and help encourage earlygrowth from the existing turf.

For fields without access to such cov-ers, a light topdressing, ranging from 1/32-1/8-inch, may be necessary to provide ade-quate protection for both the pregermi-nated and ungerminated seed.

Keep a supply of pregerminated seedavailable to fill in sparse areas andrepair any damage caused by heavyspring rains. Apply a light topdressingas a protective covering over these spotseedings.

Irrigate as needed to keep the seed andyoung seedlings from drying out. This mayrequire several light watering intervalsthroughout the day.

Monitor the growth of the existing turfduring this period. If may be necessaryto mow, following standard mowing pro-cedures, before the new seed is estab-lished.

As the young seedlings mature, grad-ually adjust your irrigation program tothe infrequent, deep watering pattern ofmature turf.

Germination and establishment peri-ods will vary with the seed varietiesselected, the amount of pregerminatedseed used, and the weather conditions.Once the young turf is well established,apply fertilizer containing slow-releasenitrogen for sustained growth and ahigh level of potassium to improve har-diness. And give the young turf as muchtime as possible to mature before sub-jecting it to the pound of play. •

Editor's Note: In addition to hisresponsibilities with the Chicago Bears'Halas Hall practice facility, their"McBubble" indoor practice facility, andSoldier Field, Mrock is currently a boardmember of both the national Sports TurfManagers Association and the MidwestChapter of the STMA. Montague is anactive member of the national STMA, aswell as the newly forming MinnesotaChapter.

For more informationon ads & products

circle theREADER SERVICE

NUMBERSlocated on the

COVER WRAPPERof this ISSUE.

28 sportsTURF