Aeration: hollow-tine, solid-tine, or both? When and where?

We recently asked turf managers four questions about their aerification practices:

  • Do you incorporate hollow-tine, solid-tine, or both?
  • When do you conduct these practices?
  • What are the biggest benefits you observe in turf health with these practices?
  • Are there any problems or challenges associated with these practices?

We also asked aerator machine manufacturers two questions:

  • For what turf conditions do you recommend using hollow tines and when for solid tines?
  • How can sports turf managers avoid problems or challenges when aerating?

The response was so good that we were forced to divide it into two parts; the 2nd installment will appear in our September issue.

Scott MacVicar, University of Washington

We have 150,000 sq. ft. of natural, sand-based sports turf at the UW and another 130,000 sq. ft. of natural, native soil landscape turf. On the game fields (track, soccer and softball) we core aerify with 2” x 3” spacing 3 times per year and 2” x 4” spacing 3 times per year. We also solid tine these fields once each at 2” x 3” and 2” x 4”. Core and solid tines are both 7” long by 7/8” diameter, producing a hole about 5” deep. These fields also get sliced with a 3-point hitch rolling slicer to a depth of about 5 inches approximately 3 times per year. We have also begun using the AIR2G2 on all of these fields and we air inject all of our fields about 3 times per year. We also spot aerify with a walk behind machine called a PLUG’R, which produces a 2” deep hole and is propelled by the tines going in at an angle and moving it forward, so the operator can hold the machine back to produce numerous holes in a small space. We use this around irrigation heads and along concrete or rubber track field edges. All of the above does not include the times that we will spot aerify certain areas of compaction, usually with the slicer or solid tines.

The benefits of this amount of aerification is overall plant health, relieving compaction and increased drainage because our biggest challenges that we have to deal with is the amount of use our fields get during that same 8.5 month window of time that we have to work on them.  Most sports in college have spring and fall seasons; one is the regular season that you see on TV but the other one always includes practice and games that don’t make that much difference to groundskeepers because we still have to have it set up optimally, whether it is a drizzly practice during the spring for a soccer game or hosting an NCAA tournament game on that field in November. The main challenge is scheduling our grounds practices around the teams wants for field use. Luckily we at the UW have a very understanding group of coaches that want our fields to be in great condition at tournament time so they have learned to listen to some of our suggestions with regards to how much use they put on those fields earlier in the season, so that they still have something left toward the end.

All of our aerification happens from March 1 through November 15 because the plant is not repairing itself during those winter months here at 47 degrees latitude.

We also use the PLUG’R machine on our landscape turf areas about 3 times per year at a spacing of 3” x 6”.

One of the aerification tricks I learned at a previous job (minimum crown baseball field) was to solid tine aerify about 3 passes (the width of the trap), in advance of the rain, along the back edge of the infield skin, right where the tarp will be dumped, to help that large mass of water to percolate faster and not flow back onto the infield skin.

Bruce Suddeth, University of South Carolina Upstate

We use only hollow tines with various pieces of equipment: a Toro 687 3point hitch with ¾” hollow tines, a Deere AerCore 1500 with ½” tines, and an AerCore 800 with 3/8” tines. We also contract out some of our deep tine aerification and that is done with 13/16” tines. What we consider our solid tine type method is using a Ryan TracAire 3-point hitch unit with slicing tines and a SISIS MaxiSlit with slicing blades.

Beginning in early May we aerify any field not overseeded with perennial rye with the Toro 687 with ¾” tines. Depending on when softball and baseball, which is overseeded, complete their schedules, it could be late May when we begin aerifying with the Toro 687 with ¾” tines.

In June and July we deep tine with either the JD AerCore 1500 with ½” tines or contract some deep tining with 13/16” tines.

The Deere 800 with 3/8” tines is used on our baseball infield, practice area, and Mini Verde golf green in late June, then again in late July while the turf is actively growing.

We don’t do much deep tining after the end of July or first of August due to the teams coming back on campus for practice and games.

We do use our TracAire slicer and MaxiSlit a good bit. The TracAire is used on all fields beginning in May on a 2 to 3 week interval. We try to alternate in the MaxiSlit about once a month during the growing season of the hybrid bermuda.

The TracAire is also used on our baseball grass base paths to help with compaction during the season whether the bermuda is overseeded or not. It’s not obtrusive and doesn’t impact play.

Any cultural practice to help open up the soil for better gas exchange and relieve some compaction is a benefit. I don’t think you can beat up hybrid bermuda enough with an aerifier.  It’s pretty obvious when you see the turf around each aerification hole greener than where not aerified. Coupled with frequent topdressing and correct nutrients and water management the bermuda responds to aerification well.

The only challenges with aerification, and this mainly pertains to our fields with installed drainage and sand channels, is that we like to remove the cores so it doesn’t contaminate the sand channels as much. Being in the Upstate of South Carolina we have a heavy clay content.  The other challenge is being able to perform the aerification during activities on the fields whether it is practice, games, camps, weather, etc.  You have to be flexible and get it done when you can.

Ken Tanner, AerWay

For what turf conditions do you recommend using hollow tines and when for solid tines?

The style of tine really depends on what are you trying to accomplish with your turf maintenance: compaction relief, alter soil profile, rejuvenation, material removal, thatch control, standing water control, nutrient incorporation, etc. All of these may require different tine styles, different depths of penetration and repetition while being cognizant of the turf use requirements.

Any tines, whether core, round solid or slicer style, have their place but all are most effective if used during a period of plant growth because it allows the plant to recover faster from the mechanical intrusion. The three key variable factors to be aware of are the plant type, soil type and soil moisture content.

How can sports turf managers avoid problems or challenges when aerating?

The #1 enemy of turfgrass is compaction and the only way to relieve it is with mechanical aerate. Period. This one soil condition is the root cause (no pun intended) of so many turfgrass challenges so a sports turf manager needs to do whatever he can to relieve that problem and restore air /water percolation in the soil as often as necessary.

The biggest problems to avoid are: 1) aerating during hot, dry conditions. This can severely dry the soil allowing plant burn around the surface openings. Recommended only if irrigation is immediately available; 2) trying to aerate when the soil is too wet. This only compounds the compaction problem; 3) not varying the tine penetration depth. Continual operation at the same depth can actually contribute to hard pan (compaction layer); 4) forgetting to get back to the basics, e.g., physically looking at your soil profile and recording the cause and effect of the various procedures. Only then will you be able to decide the correct actions beneficial for your operation.

Taking and recording compaction readings regularly in different areas will significantly improve your knowledge of what is happening sub-surface. As an added bonus those records will provide legacy proof of your compaction relief protocol for insurance purposes should they be necessary or eventually become mandatory.

Randy M. Haffling, Moravian College (PA)

We hollow tine (4″) all of our fields (baseball, field hockey, soccer/LAX, softball and a practice field) immediately following our fall sports season and again immediately following our spring sports season. We use deep (10″) soil-tines on our fields in early August before our fall sports pre-seasons start.

We couldn’t ask for better turf cover. Our aeration program has contributed toward thickening the turf and when we take samples it is not uncommon to find the roots extending 8″ or more into the soil. Our soccer field held water to the point that it was almost unplayable 6 years ago, now for approximately 4 years because of aerating the field drains and is playable after 1 1/2″ of rain.

The challenges for us have been scheduling the aerations. We used to deep solid-tine the baseball and softball fields in the spring, before the start of their seasons. However the coaches didn’t like that because they felt that it disturbed to surface of the field too much even though I always followed up with rolling the fields. The only other thing we face is making sure that the cores that we pull with the hallow-tine aerator are broken up enough as to not cause damage to turf because soil is left on top of the grass.

Will Wolverton, Wiedenmann North America

With the use of coring tines, soil profiles can be exchanged deep into the surface. Also, coring tines offer some elimination of thatch and a reduction in soil compaction. Solid tines do a good job of fracturing the soil, especially when adjusting the angle of entry, without the mess of cleaning up the cores. Another valuable tool is a variety of needle tines and hole spacing with multi-tine holders. Superintendents and managers are partial to these tines because needle tines offer minimal surface disruption and minimal effects on ball roll. Needle tines open the surface, which can become sealed by irrigation practices, while providing all the benefits associated with decompacting the soil.

Preparation is the key to a successful aerification process. Below are some items to consider:

  • Should the surface be heavily irrigated prior to aerification to ensure maximum penetration?
  • Do I have enough tines to finish the job?
  • Do I need any extra springs, belts, etc.?
  • Have I checked the condition of the aerifier and tractor for proper workmanship?
  • Do my operators know how to properly operate the aerifier?
  • What will be the weather conditions?  Will I have to alter my aerification practices depending on the weather?
  • Do I have a backup plan if something goes awry?

Unlike cultural practices that occur daily or weekly, aerification is usually only performed 2 to 3 times a year. Because of this, the condition of the machinery should be inspected far enough in advance to resolve any problems well before the aerification process begins. Re-training of operators should also be part of this process.

Paul Hollis, Redexim North America

We recommend hollow tines for several conditions which include soil exchange, thatch control, and helping new sod get established. The disadvantage of a coding time is a longer heal time, which increases the opportunity for poa annua to get established. Soils times are preferable for decompaction, increasing water infiltration and gas exchange, and giving roots room to grow.

In the end all aeration is good.

Consider the application and decide what is trying to be achieved. Choose the right machine and tine selection for the job. Do the homework[DASH HERE]is the playing field irrigated? What are the soil conditions? What is the root depth? How quickly does the field need to be playable? How frequently has the field been aerated? Don’t expect too much from the machine and make sure that the machine is setup properly and that operator is properly trained.

Allison Moyer, Collegiate School (VA)

We are very aggressive on aeration at Collegiate and we hollow tine. This year we sliced our fields for one of our aerations, using a piece of equipment called a ShockWave.  We were able to get down 15″!

We like to aerify at least 1x/month in the growing seasons (May, June, July, August, Sept). If we can fit more in, we will try.

Aeration improves our fields’ health. Overall, it helps reduce compaction from all the use and gets air to the roots. It also helps keep our fields “soft.”

Scheduling and clean up are the biggest challenges we face with aeration.

Richard Campey, Campey Imants

Hollow tines were originally designed for soil exchange; removing a tube of soil around ½” diameter and up to 3 to 4” deep. The aperture created is filled with new rootzone. Hence we have a much-disrupted playing surface, which leads to unhappy players, but we have aerated only 5 to 9% of the surface area.

Over the past 15 years we have seen micro hollow tines being used on fine turf; these cause less disruption, and they soon heal up. They seem to be used extensively for organic matter removal, only aerating to around 2” deep at close canter’s (up to 1” x 1”).

Solid tines were originally developed for summer aeration, initially ½” diameter and again 3” to 4” deep. They were noted for causing side wall compaction in certain soils, since they push the rootzone sideways. However, they do create holes on the surface that allow water and nutrients to penetrate the root systems of the grass plant.

Again over the past 10 years we have seen an increase in micro solid tining for the summer aeration on most sport surfaces.

Over the past 30 years deep tining gained popularity with machines developed with solid tines able to penetrate up to 16” deep and 1” diameter, and were able to relieve compaction provided the machine was set with maximum heave. Literally we seem to see these machines set to go in and out vertically, like banging an iron bar into the ground.

There are other forms of aeration/techniques that are common practice over in the UK and Europe, like the ShockWave and RotoKnife from Dutch manufacturer Imants BV, which are rotor linear decompactors/aerators. These have proven to be very simple robust machines that leave minimum disturbance.