There are three main ways that topdressing benefits athletic fields, says Scott Kinkead, executive vice president of Turfco Manufacturing. “First, is the ability to change your growing medium to make it more beneficial…for instance, if you have a heavy clay or you have drainage issues or compaction issues,” he explains. Sending a soil sample to your local turfgrass extension or private lab can help to identify these problems, and the best topdressing sand or mixture to help address them. Second, topdressing helps with thatch management. “Finally, and critically, topdressing helps with field safety,” says Kinkead, noting that the practice helps to smooth out the field by filling in low spots.
Randy Dufault, sales manager at Dakota Peat & Equipment, says that, of these, the most common response he hears from sports turf managers for why they topdress their field is to improve playability. “It helps to level out the field…the number one reason sports field managers are topdressing, I think, is to smooth the field out and fill in all the little divots and marks, which makes the field beautiful and level. And a lot of times it’s done to help with drainage. Soccer fields, for example, are built without a crown like you would have on a football field. So you need better drainage, and topdressing with sand helps to get that water off the surface.”
For Mike Viersma with The Viersma Companies, who is both an athletic field contractor and a dealer for TurfTime topdressers, topdressing is, first and foremost, a way to add organic material to sports fields. “We’re typically working on native soil fields that have poor soil, and we’re usually adding compost to them to help get the organic content up and help green-up the fields,” he states, while noting that he sometimes uses a compost/sand blend to get a little more sand in there.
Adding organic material through topdressing is a practice that can quickly pay dividends for the health of the turf; actually improving the drainage of the field or changing the soil structure by adding more sand can take years, says Viersma. For him, the ability of topdressing to help level the surface of a field is less significant than its ability to improve what’s beneath the surface: “The most you can put down at a time is a quarter-inch – if you put more than that down, you start to smother the existing turf. So, yes, topdressing does put down material to help level a field, but if you’re doing it one-quarter inch at a time, it takes many applications to get there.”
The right mix and materials
Whenever you topdress, Viersma says that the first step should be to take a soil sample “to see where the organic content is.” It’s a step that’s frequently overlooked, but essential to understand what type of topdressing material should be used.
“In a lot of cases, sports turf managers are testing and finding out that they don’t have enough organics,” says Dufault. A material like Dakota’s peat and sand mix can then be used. Organics are important to help hold moisture and feed the turf, he explains. When topdressing, the ratio of sand to peat (90/10, for example) can be adjusted based on what the soil of a given field needs. Some choose to topdress with straight sand, but this can cause problems by making it difficult for the field to retain moisture and nutrients – “everything is just going to flow right through,” says Dufault. He says that incorporating a high-quality organic material (one that’s fully decomposed) will benefit the health of the turf.
Buying a generic sand is one common mistake that’s made, says Kinkead: “It’s important to find a good topdressing supplier…that’s a pretty critical piece when you’re establishing a topdressing program.” Using the wrong type of material or one with incorrect particle sizes – too many fines, for example – can create a perched water table and actually make field conditions worse. “You can create concrete if you’re not doing it right,” he cautions. “Conversely, you want to make sure you don’t have too many larger particle sizes…I’ve seen places where they were getting rocks coming out of the machine.”
The bottom line, says Kinkead: “Just buying the cheapest sand you can get your hands on is not necessarily the best idea.” It’s important to identify the right material to use, find a quality supplier and use that material consistently, he notes.
“And if the field is sand-based, it’s imperative that the field continue to be topdressed with the same sand from which it was constructed or another sand with the same particle size distribution,” emphasizes Troy Carson, senior research agronomist at Toro. “The sand topdressing helps to dilute the organic matter that the plants are producing, thereby preventing the formation of layers and helping to maintain a uniform soil profile that continues to drain properly.”
Similarly, Carson says that once you begin a topdressing program, it’s critical to keep it going and be consistent, “because starting and stopping a topdressing program can create soil layering conditions that can impede water infiltration.”
“Most sports turf managers would like to be able to topdress their fields, but oftentimes budget constraints prevent them from being able to do so,” says Carson.
“However, with the increased emphasis on player safety and injury prevention, a greater number of fields are being topdressed to help make fields more uniform and more predictable. Pressure to increase the amount of play on fields is another factor leading field managers to topdress in order to improve field drainage and reduce downtime after rain events, he adds.
Dufault says that higher-end sports fields are often topdressed at least twice a year, while one application per year is more common on school and rec fields. Generally, topdressing is done at the same time a field is aerified or, if a thatch problem has developed, when the field is verticut; the sand material helps to fill in the holes while also accomplishing the goal of getting air down beneath the surface and into the soil. Dufault says that he sees fields being topdressed at all different times of the year.
“Lots of times, you have to do it when the field isn’t being used,” he notes of the key challenge. “You do it when you can do it.”