Holes in None

A soil sample reflects sand movement into the soil. All images: Ty McClellan.

The only thing constant is change. While superintendents continue aerification as a must in maintaining a healthy course, the last five years has seen quite a bit of change.

Agronomists Ty McClellan, manager of the USGA Green Section’s Education Program, and Adam Moeller of the USGA’s Northeast Region, have both seen growing differences on when courses are being aerated.

Timing. McClellan has found many golf facilities aerate less frequently in the spring and fall than they have in the past. “Much of this movement to aerate less was in response to a challenging economic climate,” he says.

An increase in scheduled outings to make up for lost revenues, declining membership and fewer rounds played all contribute to the economic shortfall. Increased outings combined with reduced maintenance budgets and less staff make it difficult to maintain recommended, aggressive aeration in the spring and fall.

“When aeration is performed it seems the golfing calendar trumps sound agronomic principles, meaning aeration has been pushed earlier into the spring and later in the fall so as to lessen the impact on play,” McClellan adds. “Unfortunately, when aeration is not performed at the ideal times of year, i.e. when the turf is most actively growing, recovery of aeration holes is slowed from as little as 7 to 10 days to a month or more.”

Aerating too early in the spring or too late in the fall, while trying to maintain pure bentgrass greens, is an open invitation for Poa annua encroachment into slow-to-heal aeration holes because it is actively growing, while bentgrass is not.

Moeller has seen the same push of “off-season” aerifying to better accommodate golfers, but understands the dilemma.

“Core aeration when the turf is actively growing and moderate air temperatures occur – late April/early May and late August/early September in the Northeast – is optimal for fast recovery with the least amount of risks,” he says. “These have been the traditional timing for the last few decades, but some are changing primarily to reduce disrupting the golf calendar. Clubs weigh the risks of core aeration in sub-optimal times with the potential benefits of non-disrupted golf in April/May and September and make their decision.

“Core aeration in a sub-optimal time is better than no core aeration at all, though,” he says.

While spring and fall aeration seem to have decreased, minimally disruptive aeration performed in the summer months is on the rise. This is generally performed using small-diameter tines – also referred to as needle or pencil tines that are approximately ¼-inch in diameter – slicing tines or water injection, Moeller says.

“Using these options there is very little, if any, impact on playability of putting surfaces,” he says. “The purpose is to safeguard turf health against summer heat stress by increasing oxygen levels in the rootzone, promoting gas exchange and minimizing root dieback.”
 

Observations. There are many theories regarding aeration strategies, McClellan says. And while some work, many do not.

The most successful aeration programs for bentgrass or Poa annua greens generally involve a combination of core aeration and deep, solid-tine aeration each spring and fall using tines ½-inch in diameter or larger combined with minimally disruptive aeration techniques (i.e. summer venting) every three weeks or so throughout the growing season, he says. For Bermudagrass greens, the most aggressive aeration practices are performed in the summer during active growth.

“Any aeration program that deviates too much from these standard aeration schedules probably isn’t all that successful long-term,” McClellan says.

Because solid-tine aeration is a very clean process that does not bring soil to the surface, many facilities have gotten away from using hollow tines, or core aeration, he says.

“In very few instances can a golf facility get away from core aeration for more than a few years, but the need to use hollow tines can be reduced if an excellent sand topdressing program is in place,” says McClellan. “With more sand applied more often there is better thatch dilution, less layering in the rootzone and a playing surface that is more traffic-tolerant because sand resists compaction. This means there is less dependency on core aeration, but it does not mean it can be eliminated, just possibly reduced and substituted instead with solid tine aeration more often.”

Moeller, too, has seen increased interest with superintendents following a non-disturbance or zero-disturbance philosophy and thatch control only through dilution with regular topdressing. “This theory supports the idea of thatch dilution and solid tine aeration only; never pulling a core through tradition core aeration,” he says. “While this may work on a limited basis, the concept is largely unsuccessful in the field and increases the chances of thatch buildup.”

In most instances, superintendents adopting the non-disturbance theory benefit from happy golfers when other courses are dealing with core aeration disruption, but at some point they realize thatch is building despite topdressing routinely.

The absence of core aeration concerns Moeller because thatch removal is one of many benefits from core aeration: compaction relief, soil modification, alleviating layering issues and improved rooting are lost or greatly reduced if this process is abandoned.

“Solid-tine aeration in place of core aeration can aid in compaction relief and rooting, but soil modification and addressing any layering issues is very limited unless core aeration is used,” he says. “If people are going to follow the non-disturbance theory, it is essential to frequently test the soil’s physical properties in the upper profile to ensure thatch, porosity and infiltration are not moving in the wrong direction.”
 

Results. There are few shortcuts when it comes to aeration that won’t ultimately result in deteriorating course conditions down the line, McClellan says. “Whereas a number of golf facilities have remained committed to sound agronomic principles throughout difficult economic times, during my travels and onsite visits to golf courses in recent years, it is obvious that turf problems resulting from soil-related problems are on the rise at a majority of courses visited,” he says.

Less aeration and less sand topdressing leads to higher organic matter accumulation in the root zones and increased soil layering problems. In fairways and approaches, soil compaction problems are becoming increasingly apparent if aeration programs are scaled back or eliminated. Increased organic matter levels and more soil compaction leads to increased soil moisture, reduced soil oxygen and stunted root systems.

“Combine this with record-breaking heat each of the last two summers for much of the United States and it is no surprise that golf facilities experiencing devastating turf loss generally were those that were not on excellent aeration and topdressing programs,” McClellan says.
 

Rob Thomas is a Cleveland-based freelance writer and frequent GCI contributor.