Ask the Superintendent – ABCs of Aeration

Welcome back, avid golfers, and I hope that you all made it through the cold weather in good shape. While March can still experience cold weather, we start to see the days getting longer and there are some pretty good golf days during the month. It is also the time of year when we start hearing the “A” word around the club, Aeration. There are a lot of mysteries surrounding aeration practices and why we even do these disruptive things to turf grass, especially to putting greens. 

Which brings me to this month’s Ask the Superintendent question: what is aeration and why do we need to do it? So, sit back and let me give you the ABCs of aeration so you can understand the methods behind the madness and help teach others the impact a quality aeration program has on highly maintained turf grass, both on the course and on our home lawns.

Aeration Basics

Aeration, by the most basic of definitions, is the process of puncturing the soil’s surface with small holes or slices to reduce compaction and help air, water and nutrients better penetrate the soil. This helps improve overall turf/plant health and reduces the need for pesticides and other inputs. Depending on the type of grass, aerations are scheduled to improve growing conditions during the peak season for the turf. Warm-season grasses are usually aerated during the middle of the summer, allowing for the most positive impact to the soil and plant, especially roots, while cool-season grasses are aerated when temperatures are cooler, allowing the turf to respond to the process with optimum results. 

When it comes to putting greens, I am sure you have asked your favorite golf club and superintendent why we are aerating the greens when they are just really getting good. The answer is complex, but we are highly maintaining putting green turf and often mowing it at or below .125 or one-eighth of an inch. It is critical that we manage the root zone for optimal health and part of that requires us to manage the amount of organic matter in the root zone upper four inches. Organic matter is essential for a smooth surface, but if the percentage of organic matter becomes too high it can seriously damage the grass. 

We use aeration to control organic matter, often we target 18 percent removal of organic matter annually, which is verified by advanced soil testing. We often incorporate topdressing with clean and properly sized sand to help us manage organic matter, reduce healing time and smooth the surface (which helps increase ball roll or green speed). Aeration is a critical cultural practice that produces healthy turf and sustainable playing conditions for golf courses. Superintendents schedule aerations well in advance but can shift these dates if weather conditions warrant a shift to protect the turf. Ask your superintendent or golf professional for the current schedule and plan your expectations accordingly. 

What is an Aerifier and Aeration Tines?

The machine that actually performs the aeration is called an aerifier, and there are many quality makers and models available for greens or fairways. They come in many colors and sizes. Most golfers are familiar with the term aerifier, but there is a lot of confusion around the aeration tine. Let’s take a quick look at the basics. The aeration tine is the replaceable part of the aerifier that actually penetrates the soil. A coring or hollow tine is hollow in the center and actually removes a section of soil and roots when used, thus creating a core that can be removed from the area and replaced with sand or other amendments. Hollow tines can be specially tipped with harder metals to last longer and take a cleaner, less stressful core, and they may also be side-eject or top-eject. The side-eject tine is better for small-sized tines, preventing soil and roots from clogging the tine. These tines are available in various sizes; the most popular are ¼,” ½”and 5/8”.  A pro tip is to know if these sizes are OD or ID, short for Outside Diameter or Inside Diameter; a half-inch OD tine is smaller than a half-inch ID tine. 

This matters when you are recovering from aeration and trying to reach a specific percentage of organic removal in a certain number of aerations. The size and spacing of aeration tines determine how much material is actually removed. Conversely, solid aeration tines do not remove a core, but rather are a single metal piece that opens a channel for air and water exchange by forcing materials outward and downward. This allows recovery much sooner but does not actually remove organic matter from the soil. Often superintendents use both types of tines, especially on putting greens or tees at different times during the year to balance playability and cultivation requirements. We also use spooning tines on larger aerifiers to cultivate lesser maintained turf areas such as roughs, as well as commercial and home lawns. Spooning tines are usually attached to a roller or drum that is lifted and lowered and is ground-driven. This type of aeration is aggressive and does create a core. You can rent smaller walk-behind models from most garden centers or hire a local lawn care contractor.

Honorable Mention

There are several other types of cultivation/aeration that are tools that superintendents use to manage turf that should be mentioned, as they are commonly partners to the larger aeration processes. Slicing or spiking is using a metal blade to make a slit or slice in the upper part of the soil and root zone to relieve surface tension and improve water absorption and increase root health. 

Vertical mowing or verticutting when the blades are set below the soil line to remove small amounts of compacted soil. Vertical mowing to remove leaf tissue only helps with leaf and light management but does not have the same impact as mowing below the soil line. Deep drill aerations or verti-drain aerations are very helpful with managing secondary organic matter layering and managing the health of the entire rootzone. These can often go up to 8” deep and can also be paired with other traditional core aerations in extreme circumstances. 

DryJect aerations are another option where we blast sand into the root zone usually with other amendments to quickly change the composition of the root zone soil. We will cover these in greater detail in future articles, but for now know that these are specialty processes that are designed to address specific conditions that impact soil health and turf quality. If you have questions, by all means, ask your superintendent. 

Conclusions

Aeration is a cultural practice that helps create healthy soils, plants and excellent playing conditions. The processes around aeration can include multiple types of tines (sizes and spacing) as well as sand topdressing and the addition of fertility and soil amendments. Turf type and maintenance history dictate when and how often aeration occurs. It is best to aerate turf when it’s at its healthiest. Soil samples and testing can accurately determine organic content of soils and help establish goals to remove a percentage of the organic matter annually; 18 percent is a common amount. 

Aeration is a normal part of the maintenance of high-quality turf, and you should ask your superintendent any questions regarding aeration scheduling and processes. Aeration is an inconvenience today that protects the future of the turf assets, but it is the “ounce of prevention being worth a pound of cure” adage. Be patient, stay informed and work with club management to make things optimum for everyone.