The quality of the soil under the grass on your lawn can affect how well your lawn prevents stormwater runoff. The more compacted and thinned out the topsoil layer becomes the harder it is for runoff to infiltrate and absorb into the ground. Limiting runoff absorption can contribute to water quality and long-term drainage issues. Compacted soil also requires more fertilizer, pesticides, and irrigation to maintain a healthy look, which in turn contributes to adding even more chemicals and pollution into local streams and creeks. Soil quality restoration is an easy and effective solution to combat lawns with heavily compacted soils, high in clay content, and low in organic matter. Soils with high organic matter content and porosity have the ability to support rich ecosystems of beneficial organisms, contribute to the overall health of a lawn, and have a positive impact on the quality of the water returning to surrounding creeks and streams.
The soil restoration process can be as simple of a process as spreading quality compost over the existing lawn. Compost can be spread loose between 0.5 to 0.75 inches across the lawn with the aid of a walk behind spreader, pneumatic blower truck, or by hand with a shovel and rake. In some instances, its helpful to aerate the lawn with a plug or deep tine aerator prior to spreading to help increase compost infiltration. New lawns can also be helped by the soil restoration process especially after new construction when soil quality is very poor. With new construction, the soil can be tilled 4 to 8 inches down to break up compacted soils and prior to seeding, a fresh 1 to 3-inch-thick layer of compost may be applied to help increase organic matter content of the new lawn.
A recent State supported project was completed in 2017 by Iowa DNR to display the benefits of soil quality restoration. They partnered with other state agencies to use soil quality restoration on the Iowa State Capitol Terrace lawns to increase water infiltration of Capital lawns, decrease the amount of runoff that goes into storm sewers traveling directly to the Des Moines River, and increase soil health to green up bald patches along several of the walking paths. The takeaway message is that soil quality restoration can be applied anywhere. The process is simple enough that it can easily be done with or without professional help. Rainscaping Iowa is an excellent place to start when searching for professional help with their list of Certified Rainscapers that have experience installing many different Best Management Practices. Also, see the links below to find more information on soil quality restoration.