Your
YARD AND GARDEN

Dave Robson

Poor turf growth, thin lawns infested with weeds, thatch problems and disease infestations often are directly due to a soil problem.

Soil compaction frequently is the cause of lawn troubles. Compacted soils drain poorly, contain little air for roots and severely retard root growth.

Cultivating with machines can reduce compaction that creates openings into the soil. Coring machines or aerators which remove small cores of soil, are the most effective type of equipment for this job. The surrounding soil will collapse into the hole, providing a loose environment for the roots to grow. Any machine or tool that just punches a hole in the soil without removing a core may be doing more harm than good. While a hole is created, the soil around the hole has been compacted, essentially defeat the purpose of creating a loose soil.

Aerify the soil when it thaws in the spring. The soil should be moist, not soggy or dry. Aerify yearly in early September if the soil is heavy clay. It doesn't hurt to aerify the soil twice a year.

Another important way to prevent compaction is to keep heavy equipment off the lawn and avoid heavy foot traffic over the same area. Even dogs running in the same area can compact soil.

Extremely severe compaction may require total renovation of the lawn and a thorough tilling. Trying to grow lawn grasses on a heavy clay soil can be difficult. Before seeding or sodding, work the soil thoroughly and mix in 6 to 8 inches of organic matter, such as compost, rotted manure or leaf mold. If you use topsoil to solve a heavy clay situation, be sure to mix it in with the existing soil on the site, rather than just laying it over the surface. If you don't, roots will grow only in the good soil, resulting in more weather related problems.

The best way to help improve heavy clay under an existing turf would be to aerify it with a coring machine and then topdress with organic matter or an organic soil. The organic matter or organic soil will filter down into the holes created by the aerifying.

Compaction and heavy clay usually cause poor drainage in the lawn, so adding organic matter can help that problem as well. If the drainage problem is not caused by compaction or heavy clay, and if it is serious enough, you may have to tile or regrade the area.

Soil pH will directly affect the availability of soil nutrients. Lawn grasses prefer pH values between 6 and 7, slightly acidic.

The only way to determine soil pH values is with a soil test. Once a soil pH value is known, sulfur will lower it (make it more acidic) and limestone will raise it (make it more alkaline). Nevertheless, don't add either without knowing the pH value.

The Illinois Specialty Growers Association is sponsoring a three-day conference on Jan. 9-11 in Springfield. In addition to the wide range of educational programming, the convention will feature a trade show with approximately 80 exhibits and popular cider judging contests. An added feature to this year's show is a direct marketing publications contest in which growers are asked to bring copies of their original promotional materials. Sessions will be offered on growing and marketing fruits, vegetables, irrigation, herbs, ginseng, Christmas trees, and labor issues. For more details and fee information, call (309)557-2107.

David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, Cooperative Extension Service, University of Illinois. You can write to Robson in care of Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. Telephone: 217-782-6515.
E-Mail: robsond@idea.ag.uiuc.edu

ILLINOIS COUNTRY LIVING • JANUARY 1997 16