George,

In lawns, core aeration is the best way to reduce soil compaction. Plan to aerate compacted areas at least once yearly, but if the compaction is severe, aeration twice yearly is even better. Due to the high levels of clay and silt in Nebraska soils, hollow-tine core aeration is most effective.

Other parts of the country with sandier soil may use solid-tine or spike aeration, but those methods are not effective in clay/silt soil. This includes “aeration shoes,” which are basically spiked aeration tools worn on your feet. Solid-tine and spike aeration push soil particles apart to allow the spike to enter the ground but increase compaction between the spike holes.

Hollow-tine core aeration pulls small plugs of soil out of the turf canopy, opening up the soil surface. As the soil cores break up, they filter back down into the grass canopy and speed up thatch break-down. This adds organic matter to the soil and improves soil particle aggregation. The soil openings are quickly filled by the growth of new grassroots. Repeated aeration improves soil structure, oxygen, water infiltration, and grass root growth.

Cores should be at least three inches deep to be most effective. If weather conditions are dry at the time you plan to aerate, water the lawn deeply two days beforehand to make it easier for the aerification machine to penetrate compacted soil and increase the depth of cores.

Wait until your lawn is actively growing to aerify. This allows the grass to recover from any damage done during aerification quickly and maximizes new root growth. Cool season grasses, including Kentucky bluegrass, fescues, and perennial ryegrass, can be aerated in spring from early April through the end of May and again in fall from late August through the end of October. Warm-season grasses, such as zoysia and buffalograss, should also be aerated when they are growing actively, from late May to late August.

Liquid Lawn Aeration

Recently, a homeowner called Nebraska Extension asked if liquid aeration is effective. They found products online claiming to provide an easy way to relieve soil compaction and wondered if they were effective. Many such products, mostly from web-based companies, claim to reduce soil compaction, but you might also find some lawn companies promoting similar products.

One web-based product claims it is "The ultimate soil conditioner for clay or compacted soil. Replaces the need for mechanical or core aeration. Reduces soil compaction and loosens clay.”

Each company has its own private mixture, but they often contain soap-like materials, such as sodium lauryl sulfate, liquid humates (basically liquid organic matter like seaweed), and “biostimulants” like molasses. The directions are to spray the mixture onto the grass and water it in.

There is no evidence that any of these products have been scientifically evaluated for effectiveness. Bottom line - it is wishful thinking to believe such a solution will have any effect on compacted soil.

1545 – Liquid Lawn Aeration – PlantTalk Colorado

1505 – Lawn Aeration – PlantTalk Colorado