Features Agronomy
Irrigation, drainage need joint budget

In some municipalities, sports turf managers work with separate budgets for irrigation and drainage, but it’s not always the best approach, claims an associate professor of turfgrass science at the University of Guelph.

“We need a water management budget – not necessarily an irrigation budget or a drainage budget – because in wet years you’re going to notice drainage problems and you’ll want to spend money on drainage,” Dr. Eric Lyons said at the Sports Turf Canada fall field day in Richmond Hill, Ont. “In dry years, you’re going to notice irrigation problems, and you’ll want to spend money on irrigation.”

A single budget to cover both irrigation and drainage works, but issues can arise when water matters are divided into two budgets, he added.

“So that means it’s easier to get support for drainage. They’ll pay for it because you’re constantly closing your fields.”

Lyons said drainage issues are easier to identify and rectify in wet years because they can be seen.

“In a dry year, trying to find where you have drainage problems can be quite difficult.”

Hard-surface playing fields are common during dry years, he said, recalling an instance when one municipality’s soccer club requested irrigation be provided on a field to alleviate the hard surface it felt wasn’t safe for its players. Irrigation shortcomings are apparent in dry years, but are more difficult to detect in wet years, “and you can garnish support for your irrigation resources.”

By combining both budgets, sports turf managers can more effectively work on both areas but must have an understanding of both, Lyons said.

“In some years you’re going to be fixing a lot of drainage and putting in a lot of drainage, and some years you’re going to be fixing irrigation and upgrading your irrigation.”

The one important aspect to remember, he said, is that soils impact management.

Among the images Lyons shared during his presentation was a photograph of a University of Guelph sports field whose soil was so bad that the field couldn’t be mowed because it led to tire rutting. He said the field hadn’t been over-irrigated or received excessive rainfall.

Root zones affect the management of a field. Soil is slower to drain than sand and contributes to more field closures after a rainfall. It is, however, more stable than sand and can handle more wear.

“We think we have a sand-based field and can play on it a lot. No, you’re just going to have to cancel less often.”

Soil fields hold water and nutrients better and require less total irrigation and fertilizer. Sand-based fields are faster to drain, leading to fewer closures due to rain.

Communicate with user groups
Communicating with user groups about the need to close some fields is imperative, Lyons said, adding that Field A might be booked and can be played on, yet Field B might be deemed unplayable that same day, even if it, too, was booked.

“That’s a hard thing to do (to communicate to user groups that a field might have to shut down after a rain event), and rather than avoid that communication, I’m encouraging you to start looking at that because as we get more and more sand-based and more and more constructed root zones, it becomes more and more important to realize that they are different assets for the municipality.”

Water and nutrients move quickly through sand, requiring more frequent fertilizing and increased irrigation. Clay holds more water than sand and retains it for a longer period of time. Irrigation, therefore, is required less often.

Municipal sports turf managers are typically responsible for the maintenance of several Category 5 fields, meaning they must pay greater attention to such issues as drainage and tire rutting when mowing.

“You need to know what’s there because you need to have field closure policies that make sense.”

Knowing which fields drain faster than others is something a field operator must know so that he can mow in a logical order. If it rained the previous night and the operator is fairly sure he can mow the next morning if conditions aren’t too wet, he has to know his pecking order.

“Is it the one you go to first typically every Wednesday, or the sand-based field that drained quicker and is a little drier and faster in the morning? It will impact how often you fertilize, it will impact your need for irrigation and the need for the type of drainage to be installed.”

Improvements to drainage begin with the surface.

“Fields wear down the middle and you lose your crown,” Lyons said. “And that’s your surface drainage.”

Water must have the ability to be moved toward drainage lines if they are present, he said.

“If you have a flat field in the middle and parallel drainage lines, is water moving along to hit those drainage lines? No, so you have to fix that problem.”

Drainage lines should run perpendicular to water’s movement.

“If you don’t have good surface drainage, you’re not going to have a good surface.”

Lyons said fields end up with water baths in high areas where the water is unable to move off and reach drainage lines. Maintaining a field’s crown is imperative, he said, adding if there is no way for water to move from the surface down to the drainage lines, nothing is accomplished. If the top three inches of an entire field are impervious to water, putting a drainage line in 45 centimetres deep won’t help. Water must be able to get through, he said.

Slit lines to move water
Slit lines can move water parallel and get it down to the drainage lines. Typically, drainage lines run perpendicular to the crown, but slit drains can run perpendicular to drainage lines. This allows water to move off the surface and towards the drainage lines.

“It’s very effective if you have an impervious layer.”

When backfilling drainage lines, it’s easy to create perched water tables. Putting fine-textured soils atop coarse-textured sands inhibits the movement of water, letting it just sit in the soil.

“When you put soil or clay on top of the sand drainage line, it won’t drain, and that’s a problem.”

If a drainage line is backfilled with sand at the surface, it can be narrow at the surface and work effectively, Lyons said.

Compacted soils allow for quicker turf green-up in the spring, but the turf will go dormant during a drought. Lyons said the presence of annual bluegrass in sod installed on a field in which the soil was always saturated creates an interesting situation.

“Annual bluegrass survives quite well without a root system. That means it can survive with a wet soil.”

Kentucky bluegrass, on the other hand, has rhizomes – good for wear tolerance and recuperative ability – but also has its stem below ground. If the stem is below the surface and the field is always saturated, the stem goes anoxic and dies. The Kentucky bluegrass dies because its rhizomes can’t survive yet the annual bluegrass in the mix survives well with its shallow root system.

High water tables can be detected on sports fields when riding a mower on the surface, Lyons said.

“Before you can fix something, you have to know that it’s broken and you have to know how it’s broken.”

Field operators who mow daily are the ones best suited to see problems on fields as they arise. When stoloniferous grasses dominate a field, the playing surface is usually either being overwatered or there is a drainage problem. They dominate saturated fields because the stem is above ground and doesn’t experience anoxia.

Aeration is a means of improving drainage, but the work should be done cleanly to minimize the impact on the turf. Soil pulled out shouldn’t be left lying on the ground to jeopardize the turf. Nor should the soil get mixed in with the sand being used to backfill lines. The work can be labour intensive, and many municipalities will elect to contract out the job.

Because operators are often the only ones to see fields on a frequent enough basis to recognize soil issues, they must be properly educated.

“Soils impact safety and the use of sports fields,” Lyons said, adding if an operator can’t get on them to mow, there might be safety issues involved. If a mower can’t get on a field, even while equipped with turf tires, allowing play to go on should be questioned.

If a field is bone dry, tire ruts won’t be visible. When they are wet, operators should first mow those they know will be sufficiently dry. These typically sit higher with free draining soils.

Operators normally mow by making their turns along the sides of a field, making the most efficient use of their time. When fields are wet, however, operators have to understand how important they are as an asset to the municipality, and their mowing routines should be adjusted to allow turns to be made well beyond where they would normally be. Instead of turning in front of a goalmouth, for example, the operator can drive through the goalmouth and make his turn behind the field.

“Little things like that can make a huge difference,” Lyons said, acknowledging the adjusted routine will be more time consuming.

Keep outlets clear
Outlets control water flow. Lyons recalled a Hamilton Tiger-Cats football game played in Guelph when a deluge of rain caused enough water to back up onto the field that the contest had to be stopped. Two to three inches of water covered the field, causing some speculation that either the field’s drainage was failing or that the artificial playing surface had been improperly installed. It was discovered that the outlet of a cistern that controlled runoff into a nearby creek to prevent flooding of an adjoining river was unable to keep pace with the amount of precipitation. The cistern’s outlet was only so big and once it filled up, the amount of rainfall had exceeded the outlet’s ability to get rid of the excess water, causing water to back up onto the field.

One of the problems with synthetic fields, he said, is that they can bubble up with air and, when a cistern finally catches up, air lifts the playing surface.

Lyons said the message is to ensure outlets are always kept clean. If fields aren’t draining yet are equipped with drainage, outlets might not be sufficiently clear.

“Poor soils equals poor turf equals poor fields.”

Lyons showed a photograph of a field in which drainage has been installed, but it never seemed to work. It was discovered a two-inch layer of soil sat on top of the drainage lines. It was trenched out and removed until sand was reached. The sand needed to be brought to the surface where it was backfilled with sand to provide dependable drainage.

The new sand was slightly coarser than the old, allowing better water movement. About three centimetres of sand were placed over the entire field with more to follow over the next two to three years to achieve a buildup of about five centimetres.

It’s an effective way to solve some drainage issues, Lyons said.

Green means safer
In Ontario, sports fields rarely need to be irrigated, he said, adding achieving a green colour for aesthetic purposes is not the primary concern. Green turf is softer than brown turf and is therefore safer. A Clegg hammer isn’t needed to detect a field’s hardness. A field’s colour will suggest which is hard and which is soft.

“Brown is the new green in golf, but for sports fields, keeping it green keeps it safe.”

If a field is equipped with irrigation, there is a lot to maintain. Again, it will be the operator on the field on a regular basis who will detect such things as sprinkler heads set too low into the turf or those that haven’t returned to their flush state. Heads set too low won’t properly deliver water and those that don’t return to their flush state create tripping hazards.

Another telltale sign of an irrigation problem is turf that surrounds a sprinkler head is lying down in the same direction, suggesting the head isn’t spinning properly and is delivering water in one direction only. The operator who sees the problem must report the matter to an irrigation technician.

A field that loses its surface drainage might be sodded through the middle, but if it’s filled in with soil as opposed to the sand it was built on, the middle of the field may be overwatered when irrigated, causing water to sit on top and not drain into the sand. This is an irrigation problem that needs fixing. The field could be irrigated to meet the needs of the middle areas, but the field’s shoulders would subsequently be under-watered.

If this is a concern for some fields, Lyons suggested tailoring irrigation to meet the middle’s needs since that is where most play occurs.