At times improving clay soil is a difficult process. I have been to places where "red/orange" is the only color the soil seems to be. It is heartbreaking, but there is help for those who really want to correct it.
Clay soils come in a variety of textures and colors. From Oklahoma's reddish orange clay to the darker gumbo clay of the deep south. There is even an edible white clay, but that is a different story.
The most radical improvement will involve removing the top layer of clay soil and replacing it with good topsoil. This is especially true if you live in a part of the world where clay seems to be the only soil you have. A less radical approach is the addition of topsoil incorporated by topdressing and core aeration. Click here for step by step information on Top Dressing Lawns.
There are also other reasons for removing the top layer to improve clay soil. Home builders are notorious for burying your good topsoil, while leaving the clay sub-surface layer on top. Regardless of your situation, if complete lawn restructuring is your chosen method for improving clay soil, here is where you will find some sound advice.
Problems Planting In Clay Soil
Clay soil has some advantages. The most notable is that it holds water and resists erosion well.
It also has disadvantages that could necessitate improving clay soil where you live. Below are some of the disadvantages of clay soils.
Before Any Work Begins
First, know that sometimes improving clay soil can a difficult process. Please know that it takes skill and knowledge to do the job right.
If you do it yourself, you may need the use of a tractor and dump truck. Tractors you can rent, but not usually dump trucks, which often require a class b commercial license. You need knowledge of rough grading, forming a subgrade, sprinkler installation (if you want them), etc.
You also need to know how your improvements could affect your neighbor’s lawn and the flow of rain water. You may need to get permits before you start any work, so be sure to check first.
Important Legal Information
In many states it is illegal to grade or add to your lawn so the finished work raises the level of your lawn making it higher than your neighbor's lawn. If you cause water to run into or flood your neighbor's lawn (where it didn't before the work was performed) you may be legally responsible to fix it.
Some people may find it best to hire a professional. Improving clay soil can be overwhelming for a beginner. However, many homeowners have done this successfully as long as they follow sound practices. If you want to do the work, but have some reservations, consult with a professional for advice before work begins.
Important: Please Read
The following advice is not a step-by-step guide on improving clay soil where extensive work is involved. Nor is this a complete How to Improve Clay Soil guide for removing the top layer soil. Improving clay soil in each lawn presents its own challenges and there is no single formula that will fit them all.
Considering if Soil Removal is Necessary
You will need to determine if the removal of any soil is actually necessary for improving clay soil at your site. You may determine that you can get by without removing any. Here are a few things to look for:
Understanding the Subgrade
Unless you are experienced at improving clay soil where extensive work is required, you might consider hiring a professional. Here’s why.
After you remove the top layer of soil, the surface you are left with will look pretty rough. There will be holes, low spots, raised areas, etc. Before the topsoil is brought in, the surface will need to be carefully smoothed out. This lower surface is often made of clay and is called the subgrade. It forms the foundation for the topsoil and must be graded just right so the water drains properly. The subgrade will have the same slope and contour as the surface will have after the topsoil is added.
The most important thing: The slope of the subgrade will need to be sloping away from the house. It needs to be as smooth as possible. If the subgrade is made too flat or slopes back toward the house, you will have problems when it rains. The rain water will often follow the subgrade surface and could pool in low spots, against the house or under foundations if it is graded improperly.
Once the subgrade is formed correctly be sure to remove any rocks, wood, or trash from the surface. You will find that some contractors will bury sheetrock, lumber, or other material under that load of topsoil because it is easier than hauling it away. However, they cause their own problems.
Problems that can occur with burying objects.
Applying Topsoil To the Subgrade
After the rough grading, the next step of improving clay soil is to bring in the topsoil. The topsoil should be six to eight inches thick for your grass to develop the best root system. Spread the topsoil evenly over the prepared subgrade or graded surface.
If you performed a soil test on the topsoil, this is the time to apply any corrective amendments, such as lime, compost, phosphorus, etc. Fertilizers can be raked into the surface easily as well.
A riding lawn mower and a pull behind lawn roller will come in handy. Rolling the lawn will not compact the lawn greatly and will help show low and high spots quickly. The lawn will always settle, but by rolling the lawn first you can instantly see where extra raking needs to be done.
You can also use this stage in the renovation process to install any drainage tiles, retaining walls, sprinkler systems, install planters, or for planting trees.
With your project of improving clay soil almost complete, the lawn is ready for seeding or sod.
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