Athletic field maintenance isn't rocket science, but properly taking care of sports turf does require the right tools for a variety of jobs.
Ross Kurcab's garage in Englewood, Colo., contains enough lawn-care equipment to make most country clubs envious-a veritable armada that includes mowers, aerators, seeders, spreaders, rollers and snowplows, and, depending on the type of machine, several different kinds of each. "We've got just about everything you could ask for here," says Kurcab, turf manager for the NFL's Denver Broncos.
The garage, of course, is not really Kurcab's. Neither is the lawn, which equates to four acres of professional football practice fields. But after 17 years of overseeing both, Kurcab is beginning to witness substantial advances in athletic field maintenance equipment. "To this day, we're borrowing golf course equipment and applying it to athletic fields, which isn't bad," he says. "But now, we're finally starting to see different equipment manufacturers designing, building and marketing equipment geared more toward sports fields." That's good news to groundskeepers everywhere and at every level.
Kurcab, who beginning this fall will manage the turf at the Broncos' new Sunday home, Invesco Field at Mile High, admits to having a lot more machinery in his fleet than the average turf manager. But in a region of the country that may produce a scant 15 inches of rain and a suffocating 60 inches of snow in any given year, he must be prepared for anything nature brings.
In addition to time-of-year challenges, Kurcab must pay close attention to the time of day when squeezing in his maintenance duties amid the multiple workouts and media events taking place at the Broncos' practice facility. It's no wonder he can be spotted expeditiously traversing the vast expanse of grass aboard a mower armed with seven cutting decks - leaving 10-foot-wide swaths of neatly trimmed turf in his wake. "We've got four acres and relatively short windows to mow in," Kurcab says. "We're looking for capacity, but also at this level we're looking for a high-quality cut. I can mow four acres in an hour with this thing." How much equipment groundskeepers have to work with depends to a large extent on the level of play their fields accommodate and on the financial resources at their disposal, but any grounds crew will find it hard to grow quality sports turf without at least the basic implements.
"The three primary cultural practices that you must have to grow quality grass - no ifs, ands or buts-are mowing, fertilizing and irrigating," says John Stier, an assistant professor in the University of Wisconsin's horticulture department. "We're not talking Qualcomm Stadium here. We're talking about a nice, safe, playable high school athletic field." Mowers log the most miles among field maintenance machinery, and some turf managers make room for more than one in their storage sheds. Mowers that are used to groom athletic fields can be of the walk-behind variety (to cut infield grass on a baseball diamond, for instance), but riders and pull-behind mowers are preferred to handle large expanses of grass (baseball outfields, as well as football and soccer fields). Depending on the type of grass and the desired quality of the playing surface, turf managers can choose from rotary mowers, in which the blade spins parallel to the ground, and reel mowers, in which blades form a rolling cylinder that scissors grass along a stationary bed knife. Both types are available in walkbehind, self-propelled or pull-behind units.
Reel mowers may cost up to twice as much as rotary mowers, but the highquality cut created by their scissors action makes reels the choice of most high-end facilities. Also favored by facilities with Bermuda grass, reel mowers can cut turf shorter than rotary mowers, promoting tillering of the plant and denser turf growth for a more consistent playing surface. "You can achieve quality cuts at the lower heights-and players are demanding lower and lower heights," Kurcab says, adding that fields cut below an inch are now common.
Rotary mowers, which shear turf blades with the sweeping rotation of the mower blade, have the advantage of cutting turf at a wider range of heights, including those that can't be cut effectively by reel mowers, which typically max out at roughly an inch and a half. A soccer field or baseball outfield may require grass cut at 2 inches, and even higher settings may be necessary on practice fields flawed by uneven contours. The rotary mower best handles such situations. In addition, rotary mowers sometimes serve as time-savers, since they can travel at a slightly faster clip and still mow effectively. As more speed is applied to a reel mower, the reels tend to fan grass flat in front of the reel blades, rendering it uncuttable.
Because they are used primarily on high-end facilities and in relatively tight quarters (for example, a stadium field vs. multiple practice fields), reel mowers are rarely found in pull-behind applications these days, save perhaps on turf farms. The capacity afforded by seven reels staggered in two overlapping rows behind a tractor just isn't called for on the finest playing fields. The more popular self-contained triplex, which offsets two reels in front of a tractor with one centered underneath the tractor driver, cuts a 5-foot-wide swath without allowing the tractor's tires to flatten grass before it's cut.
Multiple decks are still common in pull-behind rotary configurations, or gangs, which are capable of cutting swaths exceeding 10 feet. Applied primarily on practice fields or those fields that lend themselves to higher cuts, these gang mowers are often used in concert with riding rotary units better suited to trimming around fence lines, trees and other landscape obstructions.
A final distinction between reel and rotary mowers involves their own maintenance. Both require the sharpening of blades, but the more technical nature of reel mowers dictates more frequent and involved fine-tuning. While weekly sharpening of a rotary blade will keep it in acceptable shape, a reel might require attention twice a week or after every other mowing. In addition, the bed knife - that stationary blade that rides parallel to the ground-requires regular adjustment to maintain proper scissors action with the rolling reel. The reel also needs to be backlapped, a process by which a heavy abrasive substance is brushed onto the reel blades, then removed by the bed knife as the reel is spun slowly backward. This process, ideally conducted about every two weeks, removes any burrs that may develop on the reverse side of the reel blade.
While both types of mowers are basically advanced versions of the mechanisms pushed around the front and back yards of homes for decades, more hightech approaches to mowing are quickly gaining in popularity. Electric triplex mowers run substantially quieter, allowing for their use at all hours of the day, regardless of noise ordinances. A mower now available in Germany uses lasers to cut turf, making the sharpening of blades a non-issue. Finally, programmable mowers operated by a remote computer will take groundskeepers off the field entirely, except in those instances when sensors aboard the mower alert the attendant to an obstacle in its path.
"Ten years from now, we won't have to be hiring people to mow," predicts Stier. Equipment used to carry out the remaining cultural practices in Stier's triumvirate of essentials is far more straightforward. Fertilizer is distributed in solid form by using either a drop spreader, which releases product straight down onto turf in a controlled manner, or a broadcast spreader, which employs a spinning wheel to sling product outside the spreader's wheelbase. Coverage widths range from a few feet with a walk-behind drop spreader to 30 feet with a broadcast spreader pulled behind a vehicle.
Irrigation on today's high-end fields usually takes the form of an in-ground system, with as many as 60 sprinkler heads sunk a half-inch below the playing surface within the span of one football field. The more sophisticated of these systems allow turf managers to program which heads are activated at any given time. If the area between a football field's hash marks has been newly seeded, for example, the system can be programmed to irrigate that portion of the field three times a day for three minutes each time to keep the seed moist. Meanwhile, the rest of the field may see 30 minutes of nonstop irrigation every third day.
On fields where in-ground irrigation isn't an option, portable sprinklers or water cannons suffice. A sprinkler system commonly used on high school fields places the sprinkler head at the end of a long hose. As water leaves the head, a mechanism triggers a reel at the opposite end of the hose to gradually reel in both the hose and the attached sprinkler head. Four such systems spaced side-by-side are typically enough to adequately irrigate a football field.
Water cannons cover a greater area on their own, but may require booster pumps if hooked up to a water line with pressure levels below 40 pounds per square inch. While Stier lists mowing, fertilizing and irrigating as essential cultural practices, these fail to take into account one piece of field maintenance equipment that most turf managers would never be without: the aerator. "If I could buy one tool, I'm going to buy an aerator," says Mike Andresen, who applies several to the 19 acres of irrigated turf he manages for Iowa State University's athletic department. "I can grow grass without fertilizer and all that other stuff. I need irrigation and an aerator." Adds Kurcab, "Sometimes I even joke with people - that if they only gave me one piece of equipment, I'd probably take an aerator over a mower. Even though I joke about it, that's how key aerators really are to maintaining a quality surface."
No type of equipment affords more purchasing options or versatility, based on what the turf manager wishes to accomplish. The number-one goal in aeration is to loosen the soil profile so that water and oxygen are allowed to reach the turf's root zone. The two basic categories of aerators are vertical-motion aerators, which employ a mechanical piston-like action to drive metal tines into the soil surface, and circular-motion aerators, which use tines bolted to a weighted drum that is rolled over the surface.
Vertical-motion aerators can be selfcontained machines or pull-behind units, whereas the drum units are almost always pulled behind a vehicle. Tines can be hollow or solid-and interchanged, depending on the desired results. The vertical-motion aerator will usually achieve penetration as deep as the chosen tines are long, and without causing a great deal of unwanted surface disruption. These aerators also allow their operator to influence the spacing of the tine holes-the slower the aerator moves over the surface as the pistons are punching holes, the tighter the pattern of holes.
Circular-motion aerators will always leave a set number of tine holes in the surface per pass, requiring additional passes for a tighter pattern. Their effectiveness also depends heavily on the soil's moisture level-dry conditions don't allow for deep penetration by drum aerators. "They can actually disrupt the surface more than they penetrate it, so sometimes they can do more harm than good," says Stier, adding, "If they're properly used, they're still a heck of a lot better than not using anything at all."
Circular-motion units are also the more affordable aeration alternative, costing a few hundred dollars in most cases. Vertical-motion aerators can reach price levels closer to $10,000.
Core aeration, in which soil cores are removed from the profile with hollow tines and deposited on the field surface, is among the most effective forms of aeration for a number of reasons. Not only does this technique greatly enhance water and oxygen infiltration, it also effectively relieves soil compaction, it can be used to facilitate necessary seed-to-soil contact during overseeding and it can help set the stage for topdressing with the goal of amending or completely changing a field's soil composition. The latter benefit involves removing all cores from the field and filling their holes with a soil type, such as sand, that differs from the original profile-a process that may span several seasons. This is most efficiently accomplished using a topdresser, a unit similar to fertilizer spreaders in that both drop and broadcast options exist. However, topdressers spread a greater volume of material on the field and therefore come in heavy-duty self-contained or pullbehind models.
Coring can be time-consuming, since the process carries with it the added task of ridding the field of thousands of cores. Some groundskeepers attach a tarp to the rear of their aerator to catch cores as they are created, though this method rarely retains the vast majority of cores. Removal can be accomplished by passively letting irrigation naturally dissolve the cores or by actively pulverizing them with a mower or the type of drag mat used on a baseball infield. Core harvesters, meanwhile, efficiently remove cores by sweeping them into a rear-mounted tub with a rotating broom.
The entire unit may be offset from the towing vehicle's wheelbase, preventing unwanted pulverization of cores by rolling tires and creating a perfectly clean surface for topdressing. Most groundskeepers would like to core aerate two or three times each year, though once annually is more realistic given limitations of time (a heavily cored field can take a month to repair itself) and money (if the aerator must be rented).
Solid-tine aeration, in which solid spikes create holes in the soil but bring no product to the surface, isn't as disruptive as core aeration and can be applied several times during the playing season. However, solid tines are less effective than hollow tines in relieving compaction, and their holes seize up quicker, resulting in less-expansive root growth. A solid-tine unit that uses shorter, thinner tines is called a spiker. Limited in its compaction relief capabilities, these aerators are often used to assist seeding applications by pushing seed down into the soil. As with vertical-motion aerators, a number of different tines can be interchanged on circular-motion, or drum, aerators to produce varying results.
Shattertines and spoons are tines that are specially shaped to offer slightly better compaction relief than simple solid tines. Shattertines are blades configured to enter the soil, twist and then exit, shattering the profile. Spoons are tines with a small opening at the tip that, like coring tines, bring product to the soil surface, but in a form more easily broken down than solid cores.
Triangular knives can also be affixed to drum aerators to form what's called a slicer. The slicer cuts thin slits several inches deep in the soil in patterns parallel to the tractor's course and at relatively high speeds. "We can do close to an acre an hour with a slicer, whereas we can't do even a fifth of that with a core aerator," says Kurcab.
Lowest in the compaction-relief pecking order, slicers nonetheless serve two important purposes: they improve a field's drainage capacity in anticipation of rain and they propagate thicker turf growth by splitting rhizomes. The ease with which a slicer's blades penetrate the soil also means minimal surface disruption, and a field sliced in the morning can be game-ready by afternoon.
Like mowing, aeration has seen several recent technological advances. One model now available adds vibration to deep-tine penetration, thoroughly shattering even hardened soil profiles a foot or more below the surface. Cam-type action has also been employed to push tines outward after they reach full penetration, lifting soil and greatly enhancing compaction relief. A recent aeration advance to reach sports fields from the golf realm is a unit that emits high-pressure, pencil-thin jets of water, penetrating soil 8 inches or so deep. Once below the surface, this water tends to channel out from the original hole, further promoting root growth. On the surface, little if any disruption is noticeable. "You can hardly tell you were even there," Kurcab says.
Finding the right equipment to effectively and affordably maintain sports fields may mean renting the services of an aerator once a year, or purchasing one if multiple applications are desired. Certain pieces of equipment might be shared within a school district or between a university's athletic department and the campus golf course. Purchasing decisions can be made with attention to whether the equipment can serve multiple purposes, such as core aerating and slicing.
"That's the way I like to buy my machines," says Iowa State's Andresen. thing." Andresen feels fortunate that upon his arrival in Ames-which coincided with the conversion of Jack Trice Stadium from synthetic turf to natural grass in 1996-he was able to successfully lobby administrators for a $100,000 field maintenance budget. He argued equipment purchased for the football field would also benefit ISU's other facilities, right down to its cross-country course.
His superiors were finally swayed, he says, by one of his favorite equipment-related mantras: "You can't build a house with a tack hammer."
One groundskeeper's take on field maintenance equipment and its usage may not match another's, but that's only natural. A school district in Florida will face very different field-maintenance demands than a professional sports franchise in Colorado, and invariably with different equipment at its disposal. Finding what machine works best within the context of climate, schedule, financial resources and desired results is what's key, according to Floyd Perry, president of Grounds Maintenance Services for Sports Fields, an Orlando, Fla.-based consultancy.
"It's whatever works best for you," Perry says. "Somebody might say, 'Well, that's not the best for me, because I can't afford that. This is what's best for me, because it's what I can afford.' That's why I say, 'Whatever is best under your present circumstance, that's what's best for you.'"