Virginia Turfgrass Council – Mid-Season Field Checkup

March 30, 2022 | Virginia Turfgrass Council | PODCAST

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Virginia Turfgrass Journal – Tom Serensits and Andy McNitt

The heart of the fall sports season is now upon us. Although the stresses of summer heat have passed, the rigors of games and practices are not only hard on players and coaches, but the playing field too (Fig 1).

A few simple tips can help minimize the effects of field wear and tear whether you are managing natural or synthetic turf – or both.

Seed Early and Often

The importance of overseeding heavily-used fields and heavily-used areas within a field cannot be emphasized enough. Seeding is one of the most important in-season maintenance practices on heavily-used fields (Fig. 2).

You should not wait until the turf begins to thin. Seeding high-use areas before significant turf loss creates a “temporary seed bank” in the soil, which is ready to spring into action as the existing turf stand thins.

In almost all cases, perennial ryegrass provides the most in-season seeding success. Compared to other options such as Kentucky bluegrass and tall fescue, perennial ryegrass offers several advantages.

First is speed. Perennial ryegrass germinates in five to seven days and grows quickly after germinating. Germination and maturation time for both Kentucky bluegrass and tall fescue is much slower. Plus, perennial ryegrass will establish under slightly cooler temperatures compared to bluegrass or tall fescue.

Second, perennial ryegrass is less expensive (even though seed costs are up this year). You often will see blends of Kentucky bluegrass and perennial ryegrass, but for the best bang for your buck, stick with 100% perennial ryegrass. You don’t have time for Kentucky bluegrass to get established and it’s not very traffic tolerant when it’s young and immature. Plus it’s expensive in comparison to ryegrass. Previous research at Penn State shows that ryegrass is more traffic tolerant than tall fescue until both have been established for 14 weeks. That’s three and half months. You don’t have that kind of time, stick with ryegrass.

As for selecting the cultivar of perennial ryegrass to use, visit www.ntep.org and select the latest perennial ryegrass test date. The National Turfgrass Evaluation Program consists of turfgrass cultivar evaluations conducted at universities throughout the United States.

When looking at the perennial ryegrass data for several of the NTEP test sites closest to your location, don’t get hung up selecting the cultivar at the top of the list. Pick the cheapest cultivar in the top two-thirds of the list. Quality is important, but so is quantity, and if you can pick a good cultivar that is inexpensive, you can buy more seed. Also, the textbook suggestion of always mixing a minimum of three cultivars can be ignored in the case of highly trafficked turf.

First, the breeders tell us that there is already significant genetic variation within perennial ryegrass cultivars. Secondly, you are growing this grass almost like an annual. It gets worn out and replaced via additional seeding often. So the mantra is: cheap price for adequate quality and most importantly volume, volume, volume. Shoot for a minimum of 30 lbs per 1000 square feet per year. That seems like a lot, but we believe it should be set as your minimum for highly trafficked locations. Lower trafficked areas likely require much less (Fig 3.).

Timing — Dr. Dave Minner and Dr. Andrew Hoiberg (2013), authored several foundational research publications on this topic. Their conclusions were that seeding early in the season was more beneficial than seeding later. Upon reflection, this makes sense. Seed spread in mid-November doesn’t help the surface much during our fall season. Maybe it’s around to help next spring, but it’s not helping your field right now because it’s still in the bag. We’ve discussed this with Minner et al. over some adult beverages on more than one occasion. The one thing their research didn’t account for was divots. If a divot is removed, chances are the seed in that spot is also displaced (Fig. 4.).

We came to a bit of a compromise. Let’s consider the 30 pounds that the researchers found provided the highest return on investment (more seed continued to yield a better surface). The bulk of that seed (20 pounds) should be applied to the typical high wear areas at the beginning of the fall season. In Pennsylvania that would be sometime between the third week in August and Labor Day. Now with the remaining 10 pounds, apply about two pounds per 1000 square feet after each varsity football game. That will allow the JV or JH football team to cleat it in. Again, more seed is better and it’s not too late to seed right now.

Focus on the high wear areas – soccer and lacrosse goal mouths, between the hashes on a football field, etc. Low use areas may not require any seeding so spread your seed where it is needed most.

Fertilizing

For heavily-used fields, a target amount of nitrogen over the course of the growing season is 3–5 pounds per 1000 square feet. Fertilization will help your field grow out of damage and recover along with providing nutrients to newly germinating plants.

The best bang for your buck comes from quick release forms of nitrogen such as urea. There are many fertilizers on the market, but fertilizer research trials continue to show that urea often outperforms other much more expensive formulations.

It’s not too late to fertilize now but the window is closing. Fast release formulations are suggested this late in the season with a maximum application rate of one pound nitrogen per 1000 square feet.

Mowing

Of course, with fertilization comes the need to mow. Due to limited resources, one of the most common mistakes that people make is not mowing often enough. During the times that grass is actively growing, mowing once per week simply doesn’t cut it.

In most cases, a high-profile football field should be mowed at least twice per week. Believe it or not, this will help the grass resist damage due to wear. Frequent mowing promotes a healthy, dense playing surface, and it avoids post-mowing clumps from being left behind.

Clumping can be reduced by mowing when the grass is dry. Mowing when the grass is dry also results in a healthier turf plant that is better able to withstand the wear and tear of football.

Synthetic Turf

While synthetic turf typically does not wear out in a single season or recover like natural turf, proper management practices are still required to maximize safety and playability.

The infill component of a synthetic turf field helps keep fibers upright, allows for cleat penetration and provides a cushioning effect. Over time, infill levels often drop as small amounts of infill are constantly leaving the field in athletes’ shoes, clothing, equipment bags and from other maintenance activities.

Excessively low infill levels can result in accelerated fiber degradation (from both field use and UV light), fiber layover and increased surface hardness. Routine monitoring of infill levels is an integral part of managing a synthetic turf field. In fact, NFL field managers are required to measure infill depth before every game.

You can find out the target infill depth range from your turf manufacturer. If the infill level drops below that limit, additional infill should be added. That means you should have extra infill on site – crumb rubber in most cases.

Infill depth can be measured using devices specifically designed for measuring infill depth or a less expensive fire-proofing depth gauge (Fig. 5). These can be found from multiple vendors with a simple internet search and typically cost less than $20. Pay particular attention to heavy-use areas such as goal mouths if the field is shared by lacrosse and/or soccer teams.

Infill depth should be measured on a routine (monthly) basis to ensure infill levels have not fallen below your turf manufacturer’s specified infill depth range. Infill depth should be measured across the entire field (at least 20 locations), with the majority of testing taking place at locations of heavy use.

If infill is needed in these or other small areas, a few buckets of crumb rubber likely can do the job. Spread a thin layer of rubber onto the area, brush it into the fibers with a broom and repeat until the infill level is within the acceptable range (Fig. 6 & 7).

For bigger areas, larger pieces of equipment, such as a top- dresser, can be used to spread crumb rubber across the field (Fig. 8). No matter the size of the area, it is important to use the same size and type of rubber originally installed by the turf manufacturer.

Infill depth is highly correlated to surface hardness. In most cases, if infill depth is maintained at the manufacturer-specified depth, surface hardness levels will be within industry standards.

Along with managing infill depth, grooming helps keep turf fibers upright and infill evenly distributed across the field. Grooming refers to both brushing and the loosening of infill granules.

Brushing the field with equipment specifically designed for synthetic turf should be done every three to four weeks during the season. The brush should be set to “tickle” the surface and not so that the entire weight of the unit is on the turf. The brush can be set to a slightly deeper depth when leveling infill on uneven areas (Fig 9).

Aerating also helps loosen infill. Grooming units consisting of vertical star-shaped, non-powered “slicers” that roll through the turf and infill should generally be used no more than two or three times per year.

It is important that you check with your field manufacturer for grooming information that is specific to your field.

Field Inspection

Routine field inspections are another way to ensure you are providing the safest possible conditions for field users. Documenting field conditions is not only a proactive approach to field safety, it also provides a record should you be asked to provide field information or justification for new equipment, supplies, and additional labor.

A field inspection checklist is a great way to be sure to not overlook any elements of your field inspection. It also provides a record that the field was inspected should an injury occur and the safety of the field be questioned. You can make your own checklist or use one that has already been created. The Sports Turf Managers Association has created a thorough field checklist (Fig. 10) that is available on their website – www.stma.org.

For synthetic turf fields, inspections should include items such as infill depth, degree of paint build-up, seam and inlay inspection, fiber condition, and field hardness. Natural turf field inspection items typically include amount of turf cover, amount of weeds present, surface evenness, and field hardness.

Regardless of field type, items such as padding on vertical surfaces close to the field, anchoring of goal posts and goals, and drains should be inspected and conditions documents.

Reference:

Hoiberg, A. H., and D. D. Minner. 2013. Seedbanking potential of Kentucky bluegrass and perennial ryegrass in athletic fields. Int. Turfgrass Soc. Res. J. 12:p. 641-648.