AERATING LAWNS

Homeowners often overlook problems with soil compaction when aerating lawns. A variety of events, including regular lawn use, can severely restrict turfgrass growth due to soil compaction.. Traffic, both human and vehicular, over a lawn, is likely the leading cause of soil compaction. This includes activities like walking, pets running, and vehicles moving over the grass. “The movement of heavy equipment during residential or commercial construction can also compact the soil.

Turfgrass stress

Compacted soils weaken grass plants over time, reducing their ability to compete with weeds and slowing their recovery from injury. Compacted soils weaken grass plants over time, reducing their ability to compete with weeds and slowing their recovery from injury. Ensure you don’t mistake compacted soil for inherently poorly drained soil, though they can coexist. Soils in low areas, flood plains, high in clay, or swampy locations naturally hold water but might not be compacted. Soils in low areas, flood plains, high in clay, or swampy locations naturally hold water but might not be compacted.

Compacted soil

Can also contribute to the accumulation of thatch. Restricted oxygen levels in highly compacted soils, due to the compaction itself or from poor drainage, impair the activity of earthworms and other thatch-decomposing organisms. Left unmanaged, thatch can lead to serious maintenance and pest problems. Thatch accumulates faster on compacted soils and heavy clay soils than on well-aerified soils. Therefore, alleviating soil compaction in lawns will aid in thatch control.

Preventing Soil Compaction

Ideally, the best way to avoid turf problems due to compacted soils is to alleviate any compaction prior to turf establishment. However, this may not always be feasible. If the situation arises where an established turf is planted on a soil prone to compaction, consider the following tips:

• Analyze and monitor all traffic on the turf.
• Avoid continuous traffic patterns over the same turf area. This can include foot traffic, pet traffic, or tire traffic.
• If heavy traffic is unavoidable, remove the turf from the area and replace it with a non-turf pathway such as permeable pavers, flagstone steps, or mulch.
• Keep foot traffic off turf areas by using properly placed pathways and using landscape design that includes hardscape, as well as trees and shrubs, to direct traffic.
• Be careful when using large, heavy mowing equipment. Change mowing patterns often and use lightweight mowing equipment when the soil is wet. Consider avoiding the use of heavy mowers altogether on compactable soils.
• Incorporate into your turfgrass management program one or more turfgrass cultivation practices. This can include core aerification, slicing, or spiking. Of these, core aerification will be most effective.
• Keep in mind that one particular practice in itself may not be enough to relieve a compacted soil. It may take a combination of several to achieve the desired goal.

When soil is compacted, the solution is straightforward: aerify. The practice of physically removing cores of soil and leaving holes or cavities in the lawn is defined as core aeration or aerification.

Benefits of Core Aeration

• Loosens compacted soil and increases the availability of water and nutrients.
• Enhances oxygen levels in the soil, which stimulates root growth and enhances the activity of thatch-decomposing organisms.
• While removing cores of soil, the spoons or tines also sever the roots, rhizomes, and stolons. Grass plants are stimulated to produce new shoots and roots that “fill up” the holes in the lawn and increase the density of the turf.
• Reduces water runoff, increases water infiltration and percolation, and improves drainage.
• Increases the lawn’s drought tolerance due to enhanced root growth and improves its overall health.

Timing

The type of grass in a lawn dictates the best time to aerate, either in the fall or summer. For lawns with cool-season grasses like Kentucky bluegrass and tall fescue, fall aerification is ideal due to reduced heat stress and lower risk of weedy annual invasions. Ensure at least four weeks of favorable growing weather post-aerification for grass recovery.

Regularly aerating home lawns is essential for addressing soil compaction. To assess the need for aeration, probe the soil with a screwdriver. Easy penetration suggests no need for aeration, while difficulty indicates compaction. Observe the lawn’s overall health and note any thinning turf. A soil that feels hard as concrete underfoot likely suffers from compaction.

Turfgrass in high-traffic areas often requires more frequent aeration. Grasses like centipedegrass and St. Augustinegrass, which are less tolerant of traffic, need aerating more often than resilient varieties like bermudagrass, zoysiagrass, tall fescue, and some Kentucky bluegrass. These high-traffic zones can be aerated by hand, as outlined in the following section.

Ultimately, the need for and frequency of aeration depend on soil type and foot traffic. Heavy, poorly drained soils with intense traffic require more initial cultivation compared to lighter, less trafficked soils. Depending on these factors, aeration might be necessary anywhere from once every couple of years to 2-4 times per growing season.

Small Areas

Aerification can be quite affordable. For small lawns, the simplest and most cost-effective method is using a spading fork. To aerate, push the tines at least 4 inches into the soil and rock the fork back and forth. This action loosens the soil and creates space for new grass roots to grow. However, this method does have a drawback: while creating holes, it also compacts the soil around them. Additionally, using a spading fork requires considerable effort, making it less practical for large areas.

Large Areas

Aerifying larger lawns require a power-driven core aerator or aerifier, which can be rented at lawn and garden supply centers or equipment rental centers. The working parts of these machines are spoon-shaped tines or hollow tubes. As the tubes are driven into the lawn, cores of soil are removed from the ground and strewn across the lawn. Both types of tines work equally well, but the hollow tine makes a somewhat cleaner hole than the spoon type and brings up less soil. The tine size varies from one-fourth of an inch up to three-fourth of an inch and can penetrate the soil to a depth of 2 to 3 inches, depending on the manufacturer’s specifications

Ultimately penetration depth depends on soil type, soil moisture, tine diameter, and the weight and power of the aerifier. Soil cores should be left on the lawn to be broken up by rainfall and traffic. If their appearance bothers you, you can speed up their disappearance by raking them into the grass. Whichever machine you use, go over the lawn twice, once in one direction, and then in a perpendicular direction for best results.

Aerifying & Reseeding

Aerification can be combined with seeding, particularly on sparse or bare areas. If you are going to seed the lawn, you should make six to 10 passes over the area with a machine. You need to produce a number of holes, at least 4 inches apart, to improve the appearance and density of the stand. Allow the holes about a month to heal before seeding. If you overseed immediately after coring, seeds that land in or near the aerifier holes will germinate and grow much better than those between the holes, giving the lawn an uneven, speckled appearance. With a fraction of the effort and expense of tilling up the entire area, combining aerification with seeding will give the lawn a brand-new look.

Aerifying & Weed Control

When using a preemergent weed control program for annual weed control, do not apply a preemergent weed control product before aerifying. The aerifying process will open up the protective layer of herbicide and allow weeds to grow. Make all preemergent herbicide applications after the turf has been aerified.

To summarize, soil compaction is the hidden enemy to any lawn. Commercial, as well as homeowner turfgrass managers, need to be aware of the possible problems associated with soil compaction. Once soil compaction becomes a problem, remediation can be a long process. The best approach to dealing with soil compaction is to prevent it from the beginning. Anticipate compaction occurrences and implement the proper turf cultivation practices to reduce the chance of turf failure.