Homeowners have likely heard of core aeration as a way to relieve soil compaction in the lawn. While that is certainly true, coring has several more benefits for the grass plant, microbial activity in the ground, and thatch management.
When the soil beneath the lawn is compacted, grass roots grow poorly, staying nearer the surface and more readily impacted by droughts. Coring allows the soil to relax and expand into the vacated core. This promotes deeper roots because it allows more soil oxygen into profile along with water, and it also means better disease resistance. Another benefit is the lawn has greater ability to remain green and actively growing during a brief drought.
If any topdressing is done with quality black dirt or using well composted organic matter, this material will find its way into the core as well, improving the soil profile. Any kind of organic matter also will support the microbial life in the ground, improving the symbiotic relationship between the grass root system and the microbes in the soil. Organic matter supports the microbes by supplying carbon, which is key to their existence. Research shows that if the soil is in good health, teaming microbial activity, they in turn support good grass growth by providing critical elements to the plant.
Core aeration also will assist the homeowner with maintaining thatch levels under a half-inch. Homeowners hearing the word “thatch” often think the worst. In fact, having some thatch has benefits to the lawn. Thatch will act as insulation protecting the crown of the grass plant from quick changes in the weather, such as a sudden drop in temperature. Thatch also provides a cushion from foot traffic, again protecting the grass plant crown from being crushed or damaged. Coring breaks through the thatch layer opening up those opportunities for air and water movement already mentioned. When the core is ejected by the machine, there is a plug of soil that is left on the surface. That soil contains those microbes that can now begin to break down the thatch layer.
Core aeration alone will benefit the health of the lawn. Combining top-dressing with any re-seeding or over-seeding, along with regular watering for at least three weeks will really turn the lawn around. A late summer, early fall fertilizer (lower in nitrogen than spring formulations) will provide the lawn that last bit of energy to assist in loading up the root system with food reserves to get it through the winter and give the lawn a head start next spring.
About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.