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Soil and Site Preparation for Lawns

Soil

Properly preparing the soil is critical to the success of home lawns.

Success or failure of a home lawn is closely tied into how well the soil and site was prepared prior to lawn establishment.

Eliminating weed problems existing on the site is an important first step. Perennial weeds, such as quackgrass or tall fescue, need to be controlled prior to lawn seeding or sodding. Weed control options include digging by hand, repeated soil tillage or using a systemic (moves within plant) nonselective herbicide, such as glyphosate, sold as Roundup and other trade names. Organic products are becoming more popular as well. Read, understand, and follow all label directions whenever using any type of control product to be sure you will be getting the expected level of control necessary.

Before seeding or sodding, it's important to thoroughly work the soil. Amend poor soils, such as heavy clay, by adding organic matter. Sources include compost, rotted manure, peat, and quality topsoil. Sand is not suggested as a material to improve clay soils for home lawns.

In addition to modifying the soil structure organic matter contains micro organisms that work together with the roots of plants to absorb the nutrients in the soil, so there are additional benefits of using organic matter as part of the soil building program. Incorporate these materials into the existing soil, rather than layering them on the surface. A goal is to have six inches or more of well prepared soil, and beyond that is impractical around large trees where many roots are found within the dripline.

Soil testing is suggested prior to establishment and should be done during the planning process. Soil testing reveals the oil pH and amount of available nutrients such as phosphorus (P) and potassium (K). If major modifications are needed, it is easier to make these prior to establishing the lawn. Check with your local Cooperative Extension Office for details on how to take a soil test and go to (http://urbanext.illinois.edu/soiltest/) for a listing of soil test laboratories that provide homeowner recommendations.

Starter fertilizers should be mixed into the soil surface prior to lawn establishment. These are typically high in phosphorous. Balanced fertilizers typically have balanced ratios of nitrogen, phosphorus, and potassium (N, P, K), such as 10-10-10 or 12-12-12. Balanced fertilizers can be used if a starter fertilizer is not available. Soil test results may show a shortage of phosphorus or potassium, which would influence the decision of the fertilizer formulation used.

When preparing the soil, it's important to establish a favorable final grade. Rough grading should include removal of any rock or other debris. Avoid burying construction debris, as this could cause problems for the grass later. Eliminate any depressions or raised areas. Final slopes should be one to two percent away from buildings (1 to 2 feet drop per 100 feet of run) to assure good surface drainage.

Soil preparation should be done when the soil is not too dry or wet as tillage will destroy soil structure, and create problems with air and water holding capacity and drainage after a rain event. It can take years to return to its former state.

Taking shortcuts in soil and site preparation often leads to assorted lawn problems later. Take the time and effort to do a thorough job before seeding or sodding that includes soil testing, nutrient and soil amendments, creating uniformity of the subsoil and final grading.