The big and the small of it

Aerification is a dirty word to some golfers. It conveys images of greens filled with holes and putting surfaces that are at best inconsistent and, at worst, may not be playable at all.

But serious golfers understand that aerification is necessary to sustain healthy turf. Aerification counters the effects of foot traffic and compaction while also minimizing the risk of disease.

“You need to have an ongoing program,” says USGA Greens Section Course Consulting Service senior agronomist Chris Hartwiger, “to remove organic material and replace it with sand for the purpose of keeping desirable physical properties in the upper root zone.”

Organic material begins to accumulate in a green complex literally from the moment grass is planted on it. Ideally, the grass takes root and grows downward through the soil; the root system provides the plant with the necessary water, oxygen and nutrients.

But over time, the level of organic material on the soil increases to the point where it collects in the soil pores and stymies the growth of the plant.

Dr. Bob Carrow, a renowned turfgrass specialist from the University of Georgia, did a study on the issue of organic material in green complexes. His data, which was compiled during the mid-1990s and published in 1998, indicated that when the amount of organic material in a sand-based green reaches 3 to 4 percent by weight, the amount of pore space in the green complex begins to decrease, making the turf more susceptible to oxygen deprivation, heat stress and disease, among other things.

So it’s a given that organic material must periodically be expunged from greens and fairways and replaced with sand.

But what’s the best way to achieve that aim? Are large tines or smaller ones the best approach? Opinions vary on the subject.
 

Finding a fit

Many superintendents prefer larger tines, with a diameter of perhaps a half- or five-eighths-of-an-inch, with a 2-by-2-inch spacing pattern.

Dr. Beth Guertal has taught at Auburn University for more than two decades and has done extensive research in the field of turf management. She notes the advantages of using larger tines, whether hollow or solid.

“Those significantly reduce compaction in that top two inches,” she says. “They remove a little bit of thatch, they stimulate root density, they stimulate chute density … If you don’t have deep compaction or a layering problem, they work really well.

“The only thing is, you need to make sure it has a little bit of a shaking or quaking effect so you don’t see the development of a sub-surface tillage pan. [But] today’s newer equipment takes care of some of that.”

Some superintendents will choose smaller tines with a diameter of one-quarter or three-eighths-of-an-inch with a 1-by-1-inch or 11⁄8-by-11⁄8-inch spacing pattern.

There are some advantages to smaller tines. Aeration holes heal more quickly which results in less disruption of play. The downside of this practice is the aeration holes are more difficult to fill. As the hole size decreases, the likelihood of sand particles bridging over the surface of the holes increases.

“The larger the hole, the easier it is to fill it with sand,” says Hartwiger, who’s based in Birmingham, Ala., and works with golf facilities throughout the southeast.

A superintendent must develop an approach best suited to his or her own circumstances.

Don Brown has spent 34 years as the superintendent at White Manor Country Club in Malvern, Pa., outside Philadelphia. During that span he hosted an LPGA Tour event for six seasons and has also hosted what was then the Senior PGA Tour.

While some superintendents tend to rely on one particular size of tine, Brown has taken a different approach over the course of his career.

“We have changed a little bit back and forth over the years kind of adjusting for the need at the time,” he says. “I don’t think you can say that, ‘This is the size you use and that’s the size you’re always going to use forever.’ We have varied our size, not so much year to year, but every couple years it seems like we get into a slightly different aeration mentality.”

It’s a matter of choosing the tine that’s suitable for the soil conditions at a given time, Brown says.

“There was a time when we had a good bit of organic material in our greens and we went to a larger tine,” he says. “We were punching holes that might have been .580 inches and spaced very closely together, about an inch-and-a-half apart, but then we reached a point where we didn’t feel we had to remove as much organic, so we went to a smaller tine, .406-something and maybe did more like two- to two-and-a-half-inch spacing because I didn’t feel like I needed that much material removed.”

Aeration changes and evolves depending on the real need, Brown says.

“Is there a lot of organic that we need to remove? Or is there not enough to create an issue and we can back off?” he says. “We can have fewer holes, or holes that are a little bit smaller, which impact play less.”

In 2002-03, White Manor was completely redesigned by architect Bobby Weed. The golf course was closed for most of two seasons before reopening in late summer of 2003. The new course featured bentgrass greens and fairways, giving Brown a new a new set of conditions to deal with.

“We were maintaining a sand-based green that had a very aggressive-growing bentgrass,” he says. “That creates a lot of organic matter. We made some significant changes to our aeration program.”

Those changes included using a smaller tine in a quad time holder.

“Initially we used a very, very small tine in very tight spacing in order to keep the air channels open. Once the greens became established and started to develop some organic material, we started to get a little bit bigger with the tines and a little closer in our spacing until we reached the point where we had the organic issue under control. We still punch as often, but not as big a hole and not as close together.”

Brown aerifies twice a year, usually the last week of March or first week of April and again during the third or fourth week of October. Ideally, he’d prefer to schedule aerification in May and early to mid-September, but the busy golf schedule at the club makes that impractical.
 

Timing is everything

Steve Aitken has spent 21 years at Aspen Golf Club where he’s not only the head superintendent but also the director of golf.

The Colorado municipal facility sits 8,000 feet above sea level. The golf course is open from mid-April to late October, but the peak season is short, spanning the period from late June to mid-September. The club hosts 28,000 to 30,000 rounds each year.

Because of the shortened season, the cooler temperatures (even during the summer temperatures dip into the 40s at night) and the dry climate, Aitken aerifies just once each season; in late April or early May, theoretically after the last snow of the season has melted. He’s toyed with the idea of aerifying in the fall instead.

“I really feel at elevation you need only one core aeration a year,” he says. “Otherwise you’d have the place torn up most of the time.”

Aitken prefers to utilize a half-inch tine with a 2-by-2-inch spacing pattern. “We’re not using a solid tine,” he says.

“We’re using a solid tine that actually holds the core. That lets us keep our head above water as far as thatch accumulation is concerned.

“We’re trying to eliminate thatch and create a firm surface. When we do go in, we’re not using a solid tine. We’re using a hollow tine one-half inch in size that actually holds the core. You’re at least keeping your head above water as far as thatch accumulation. You don’t want it to accumulate.”

Aitken says the dry climate in the Rocky Mountains accelerates the aerification process. “I think it makes it go a little quicker,” he says. “We can pull out our cores and they’re fairly dry and they’re light, so the pickup process goes pretty quickly.

“And when you’re applying sand, the drying time is minimal. I think the whole procedure goes pretty quickly. You’ve just got to make sure you’ve got irrigation to water everything in afterwards because everything is so dry.”

Some facilities and golf course owners are reluctant to aerify at all. They cite the revenue lost while the golf course is closed for aerification.

But for a daily-fee operator looking to turn a profit, aerification is part of the cost of doing business, just as the owner-operator must change the oil regularly in his car.

Delaying aeration may save money in the short term, but it puts a golf course at risk. Too much organic material in the soil can lead to other problems, although Hartwiger points out those problems don’t always manifest themselves immediately.

“When you defer aeration, you definitely run the risk of poor plant health,” he says. “But sometimes, for greens to really turn up their noses, you need another catalyst like a super-hot summer. You can go a long time without terrible secondary problems and then you get a really hot summer and ‘boom.’ The greens don’t perform at all and you’re wondering what happened.”