It’s no secret among turf management professionals that it isn’t easy to properly maintain a natural grass athletic field. Athletic turf managers not only have the usual challenges faced by any turf professional such as adverse weather conditions and tight budgets, they also face unique difficulties such as coordinating turf maintenance with busy practice schedules and dealing with multiple types of users who may have competing interests (in the case of facilities who serve both amateur and professional athletes).
The good news is that through careful planning and a systematic approach, these challenges are not insurmountable. The first step in any successful natural grass athletic turf maintenance program is education, and to that end we’re providing a high-level overview of what exactly goes into properly maintaining a typical natural grass athletic field, including field scheduling, mowing, fertilization, irrigation, aeration, and overseeding.
Scheduling athletic field turf maintenance
A successful athletic field turf maintenance program begins and ends with scheduling. In a perfect world, a field would begin the season of primary use with 100% turf coverage and grass that is at least four months old. The reality is that more often than not this is simply not possible, but one thing that will make it more likely is proper scheduling of maintenance.
First and foremost, this means that there must be excellent communication and mutual respect between everyone who uses and maintains the facility, including coaches, players, athletic directors, and turf professionals.
When everyone has a voice and feels like their needs are being met, it will create a working environment much more conducive to healthy turf:
- It will allow for rotating areas of play to allow for better turf recovery
- It will allow discussions to occur about finding alternate areas for some activities if possible (such as holding band practice on a parking lot instead of the football field)
- It will make it possible for field managers to have the authority to restrict field use during times when damage to turf is more likely to occur
Given the fact that a typical athletic field will start to show wear after 10 events and will be significantly reduced after 25 events, if proper maintenance is not scheduled from the get-go, it will be difficult or even impossible to catch up later.
Mowing a natural grass athletic field
Of all the activities associated with maintaining a natural grass athletic field, mowing is the one that needs to be done the most often. In fact, in most cases, athletic fields should be mowed at least twice per week starting in early spring as the turf begins to grow (NFL teams with natural grass fields mow 3-5 times per week).
The need for frequent mowing is due to the fact that for good turf health, at no time should more than 1/3rd of the leaf blade be removed during mowing. Also, frequent mowing promotes a dense playing surface and reduces clumps that block sunlight and become tripping hazards.
Obviously, most athletic fields are not going to have the maintenance budget of a typical NFL stadium, so the need to mow frequently must be balanced with the need to save money. Therefore, the question becomes, how high can the grass be allowed to get without causing damage to the turf when it’s cut?
Here are some factors that must be considered when answering that question:
- How mowing relates to wear tolerance: A field mowed at a lower mowing height will wear out faster than a field mowed at a higher height.
- How mowing heights affect turf density: Higher mowing heights produce less dense turf. Conversely, the lower you mow, the denser the turf.
- Mowing height also affects the depth of turf roots: The lower the mowing height, the shorter the roots.
As a rule of thumb, Bermudagrass should generally be mowed at a height between ¾ and 1¾ inches, and Kentucky bluegrass, perennial ryegrass or tall fescue should be mowed at a height between 1½ to 3 inches. Whatever mowing height is used at the beginning of the growing season should be maintained throughout the year—do not adjust mowing height up or down during the year.
Fertilization of natural grass athletic fields
Creating a good fertilization plan for natural athletic turf really comes down to answering two questions: how much fertilizer do you need to apply, and when do you need to apply it?
How much fertilizer to apply
The answer to the first question begins with soil testing, which should be done once every 2-3 years. The soil test results will provide data about how much of each of the three main nutrients needed by turf are in the soil: nitrogen, phosphorus (phosphate) and potassium (potash). Higher levels of nutrients in the soil means less fertilizer will be needed.
Fertilizer is labeled according to how much of each key nutrient it contains by percentage. So, for example, a fertilizer with the label 15-10-5 fertilizer contains 15 percent nitrogen, 10 percent phosphate and 5 percent potash.
Along with data about how much nutrients are in the soil, the test results should also include recommendations about how much fertilizer to use, which is typically given in pounds of nitrogen per 1,000 square feet of turf. You can then combine this information with the label on your fertilizer to calculate how many pounds of that particular fertilizer you need to use to get the recommended level of nitrogen.
When to apply fertilizer
Fertilizer should be applied during the time of year that grass is actively growing.
For grasses grown in the north (Kentucky bluegrass, perennial ryegrass, tall fescue), this means applying fertilizer in the spring and fall seasons.
For bermudagrass, which is normally grown in the south, fertilizer should be applied in the summer.
Fertilizer should also be applied to an athletic field if the turn is damaged from heavy traffic or a game played on wet soil.
Regardless of when fertilizer is applied, it should be watered in as soon as possible after application, which brings us to the next step in natural grass athletic turf maintenance—irrigation.
Irrigation of Natural Grass Athletic Turf
As with fertilizer, the questions that need to be answered in a maintenance plan are “how much” and “when”, but unlike with fertilizer the issue is slightly complicated due to the fact that mother nature will participate in the irrigation process—and she doesn’t know or care about your irrigation schedule.
Another factor that must be considered is how water is going to be applied to turf on an athletic field. If water is applied at a rate faster than it can be applied to the soil, it will be wasted, so it’s important to have a way to closely monitor and control the amount of water applied to a given area.
The best way to do this is with an automatic pop-up irrigation system. Systems that rely on manual movement and positioning of sprinklers will inevitably end up wasting water.
As to the question of how much water to apply, that is determined by three factors: the water-holding capacity of the soil, the amount of moisture present when irrigation is started, and drainage. The idea is to ensure that the entire root zone of the plants will be wetted.
A good rule of thumb for determining when to water turfgrass is to irrigate deeply just as the plants are beginning to wilt. A common mistake is to water natural grass athletic fields too often and for too short a time. If you notice a bluish-gray hue to the grass in the heat of the afternoon or footprints that do not recover immediately, it’s a sign of drought and means the turf is not being properly irrigated.
Whenever possible, fields should be irrigated in the morning so that it is less likely to encourage disease. Also, avoid irrigation just before heavy use of the field to avoid compacting the surface.
Aeration is an often neglected part of natural turf athletic field maintenance, but it is very important in order to help prevent soil compaction and to allow air, water, and nutrients to reach the grass roots.
Ideally, it should be done 4-8 times during the season of primary use, concentrating in the high use areas like soccer goal posts and between the hashes of football fields.
There are many different methods of aeration. Most athletic fields use tractor-drawn aeration units such as the Toro ProCore 1298, but some use walk-behind units. Some units simply rely on the weight of the equipment to push tines into the ground, but others mechanical or hydraulic systems to drive the tines deeper.
There is also the question of whether to use solid or hollow tines. It is generally recommended that hollow tines are better for soil-based fields, whereas solid tines are better for sand-based fields. Whichever type of tine is used, the diameter should be a minimum of half an inch, and should penetrate 2-4 inches deep. About 20-40 holes should be punched per square foot of turf.
The final natural grass athletic field maintenance task that must be scheduled in order to maintain healthy turf is overseeding. Overseeding is the process of applying seed to an existing field in order to improve turf density and help it recover from frequent use.
Research has shown that the best grass to use for overseeding is perennial ryegrass, even if a different species was used originally. Using Kentucky bluegrass for overseeding, on the other hand, is completely ineffective due to the long germination requirement.
If the budget allows for overseeding of an entire field, that is ideal, but if not then concentrating on high-traffic areas is the next best option. Overseeding should be done after aerification and after the cores have been broken up, which will provide a better seedbed. After applying the seed, water the field before the seedbed has a chance to dry out.
Is it worth the cost to maintain a natural grass athletic field?
When considering everything we’ve mentioned above that needs to go into properly maintaining a natural-grass athletic field, it’s understandable why some athletic facilities consider switching to artificial turf fields. However, the decision is not as clear-cut as it may seem.
Artificial turf fields have their own maintenance needs and expenses, which are comparable to the expenses for maintaining a natural grass field. In fact, studies have shown that over the long term, natural grass athletic fields are actually cheaper than artificial turf.
There’s also the health and safety of the athletes to consider, and environmental concerns.
While an in-depth discussion of natural grass athletic fields vs artificial turf fields is beyond the scope of this article, the bottom line is this: while the maintenance needs for each type of field are different, neither type can be sustained without a comprehensive maintenance plan.
For natural grass athletic fields, a maintenance plan based on known best practices and the latest turf science that includes mowing, fertilization, irrigation, aeration, and overseeding will keep the grass healthy year-round and provide a safe playing surface throughout the season.