By Bob Dailey
The old adage “it’s better to put a $1 plant into a $10 hole than it is to put a $10 plant into a $1 hole” also holds true for lawns.
The amount of soil that lies beneath many lawns in the area is woefully inadequate. Sample plugs taken show that some sod has less than a half inch of soil beneath them. Beneath that, more often than not, lies an impermeable layer of clay. Grass roots have a difficult time penetrating that clay barrier. It also causes irrigation water and rain to sheet off into the streets, making watering more expensive and wasteful. In some places, sod was laid directly over clay or even gravel, with no soil added. Be wary of contractors who leave behind a thin layer of soil under the sod.
As the adage above alludes to, soil is the most important component when installing a new lawn. The soil under the lawn should cost more than the lawn. The first and most important thing a homeowner can do is to have their soil tested. Texas A&M’s Soil, Water and Forage Testing Laboratory provides homeowners with analysis of soil. For more information on soil tests, residents can call the Montgomery Master Gardeners Hotline at 936-539-7824. Test results will indicate the pH of the soil, any deficits in macro-nutrients (like nitrogen, potassium and phosphates), and organic content. For instance, if the soil is low in nitrogen, blood meal or other organics can remedy that problem. It’s good to test any new soil brought in as well.
Don’t be stingy when it comes to soil Lawn experts agree that the ideal soil depth should be at least four inches for a healthy, long-lived lawn. If affordable, experts recommend more than that. Adding enough soil is not cheap. Adding four inches of soil to a 5,000 square foot lawn requires about 62 cubic yards of soil. While sod for that much area will cost about $700, adding four inches of soil could cost upwards of $1,000. Believe it or not, in time this will pay for itself, through increased health of the lawn, less watering, fertilizing and weeding, and, of course, a considerably improved appearance.
|AreaDepth (in inches)|
|100 sq. ft.||1/3||2/3||1||1 1/4||1 2/3||2 1/6|
|500 sq. ft.||1 1/2||3||4 2/3||6 1/4||7 1/2||9|
|1,000 sq. ft.||3||6||9 1/4||12 1/3||15||18|
|2,500 sq. ft.||7 3/4||15 1/2||23 1/4||31||37 3/4||45|
|5,000 sq. ft.||15 1/2||31||46 1/3||61 3/4||77 1/2||93|
Amount of soil needed (in cubic yeards)