Aerification: Updates and Process Description

Old Date: May 24 and 25

New Date: May 26 and 27
Aerification of the greens is a necessary process to reduce thatch and provide a healthy playing surface for the members at Oakfield. There are certain environmental conditions that are necessary to a successful aerification and the recent inclement weather will impede steps of the process. With double the amount of precipitation that is average for May (and approaching triple); this month has been one of the wettest in history.

As of today, the aerification process has been rescheduled for Thursday May 26 and Friday May 27.  

Because of the forcasted weather for the weekend, and the desire to reduce conflict with the golfers on Saturday, the time line for completing the process is a less of a window than normal. To compensate for this, the spaces between aerification holes will be increased.  Increasing the hole spacing reduces the amount of surface affected, but will produce less cores to be picked up and required less sand to fill the holes.  With the greens being so soft, the increased distance between the holes will help to reduce depressions from the equipment driving over the green.  

In the event that the conditions do not improve and the process cannot be under taken, the Greens Committee is recommending that the spring aerification, for this year, be replaced with cultural practices that target the reduction of thatch and compaction.

Aerification is a vital portion of the Maintenance Program at Oakfield and omitting the spring aeration should not be taken lightly. It is recommended that each year 15% of the surface of the green be removed in order to combat a build up of thatch. Thatch reduces the infiltration of water, nutrients and provides an excellent home for pests. With the absence of the of the spring aeration the impacted surface of the greens will be reduced to 7.5%. To increase the percentage of surface area de-thatched, a more aggressive cultural program will be followed throughout the playing season. These practices will include more frequent topdressing, more frequent verti-cutting and venting the greens with pencil sized tine on a monthly basis.

These steps are all necessary to keep the playing surfaces as healthy as possible, while providing excellent playing conditions for the Membership at Oakfield Golf and country club. 

Below is an in depth description of the process.   

Aerification

“Why do we aerify the greens just when they seem to be doing so well?”

Every year during the golf season we are asked this question. The process can be disruptive to play and detrimental to playing conditions, however it is a necessary evil to keep the greens healthy. Aerification has many benefits that outweigh the disruption that it causes. Some of the benefits include compaction relief, increased nutrient infiltration, increased water infiltration, increased gas exchange, increased plant growth due to the removal of competing plants, creation of new plant by severing stolons and strengthening of the plant mass to prevent weed invasion. Perhaps the most important benefit of aerification is the removal of thatch from the playing surface.

Thatch is the layer formed from plants regenerating new leaves and the old dying down. The older leaves fall to the surface and mix with soil to form a mat, which if not removed, can prevent water and nutrient infiltration, gas exchange, increased insect population (a perfect home), increased disease and compaction issues. There are two ways that we monitor the thatch levels on the playing surfaces. The tried and true way is with a soil profiler, a device that pulls a section view of the soil profile from the surface to approx five inches below the surface.

The second is by sending soil and surface samples to a soil testing company that measures the organic matter levels in the sampled area.

Aeration is the most effective way to physically remove organic matter from any playing surface.

There are some steps that we take in preparation of Aerification that you may not be aware of. The greens are fertilized with fast release nitrogen a few days prior to the event to encourage a growth spurt during the event. This helps to facilitate the filling of the holes and increase stress resistance. Watering is reduced to limit the surface moisture for cleaner core removal.

In the fall of 2009 Oakfield golf club purchased a Pro Core 648 made by Toro. This machine is wider and faster than the old machine and much cleaner at removing the cores. The aerification process is basically a series of steps, with aerofying being the first. The quicker that the cores are pulled than the faster we can move on the next step.

The cores, which are approximately two inches long, are pushed off the green using snow shovels. Although very labour intensive, the use of plastic snow shovels prevents tearing or gouging to the green during this step.

After being piled the cores are then picked up and carried off site. The cores are stock piled and used to level low areas like trench lines and cart path edges. Because the cores are plugs of entire plants, they continue to grow just as sod might. It’s recommended that we impact 15% of the playing surface during the course of the season, spread out over three coring events. Using a mathematical equation we determine that half-inch thick tines at two inch spacing will meet the requirement to remove 15 % of organic matter from the surface of the green.

The next step in the aerification process is to fill the holes and return the green to normal putting conditions.

Even before greens keepers were cutting grass to improve playing conditions they were adding sand to surfaces. During that time period most of the sand was applied using shovels and horse drawn carts. Obviously there have been many advances in the technology since that era. Oakfield has three topdressing units, two for heavy topdressing and one for the lighter applications. Using a combination of speed and setting the units can be setup to distribute varying amounts of sand. All three units are implements that attach to utility carts and can be exchanged to boxes for regular duty.

Top-dressing sand is unlike beach sand or brick sand, it’s made up of reasonably uniform particles that when piled together don’t compact or bind. Concrete sand, by comparison, is made up of aggregates of different sizes to fill the air spaces between particles with the intent of creating a dense solid. By using sand that doesn’t compact we are able to create air spaces for nutrients water and gases travel through. This allows for more air for microbial activity.

The USGA has recommendations as to the size and shape, or gradient index, of sand that should be used for both the building and top-dressing of a golf course green. Frequency and amount at which sand is applied is also recommended by the USGA and our agronomist. The current year’s recommendations for are .5 cubic yards of sand per 5000 square feet of green space per topdressing event. This delivers just slightly less than one centimetre of sand per year. These events are considered light top-dressing and are performed once a month (weather permitting). At the lighter rate the sand can be worked in to the lower canopy of the turf by simply rolling and watering.

During the Aerification process application rates are drastically increased. Because the goal is to replace the material removed from coring sand is applied at a rate of six cubic yards per 5000 square feet, and in some cases, an additional application in the days following may be required to top off the holes. The weather plays a critical role in heavy topdressing because the initial application is quite thick and requires time in sun to become dry enough to work. Wet sand will not percolate into the coring hole and has a tendency to “crust” when worked.

After topdressing the next step is to apply seed to the green. Bent grass seed is very small and is difficult to broadcast in a uniform fashion. We mix the “Alpha” species of bent grass seed with an organic fertilizer as a medium for delivery. The seed and fertilizer is then broadcast using a walk behind spreader. When sufficiently dry the sand is brushed in three directions using a coarse brush. The coarse brush stands the turf up and works the sand under the canopy. The bristles of the course brush are stiff and have the tendency to aggressively move the sand, therefore as a final step the green is dragged using a cocoa mat. The coco mat is made up from fibres of the cocoa tree embedded in a rubber sheet. The rubber backing of the coco mat flexes with the undulations in the green and gently drops the sand into the aerification holes. Due to the abrasive nature of the sand, the number of times the brush and cocoa mat can travel over the green is limited. Too many trips can bruise the grass blades and cause damage.

The next step is to heavily water the greens. The water washes the sand farther into the aerification holes and exposes any unfilled areas. The water also relieves some of the stress from the abuse of the brushing and matting process. Each green is watered for approximately 45 min. Green speeds become very slow during this process largely due to the amount of sand but also because the height of cut is increased to help the grass recover faster. After a few days of cutting and watering the sand settles down and green speed returns to normal.