When Improving Clay Soil Requires Extensive Dirt Work

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 variety of textures and colors. From reddish orange of Oklahoma clay to darker gumbo clay in the deep south. 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 well. However, the disadvantages often out weigh the advantages and could lead to the necessity of improving clay soil where you live. Below are some of the disadvantages of clay soils.

• Clay soil compacts easily.
• Compacted clay soil will contain less oxygen and water.
• Clay soil can bake in the hot sun becoming hard as a rock.
• Root penetration is more difficult in clay than in lighter soils.

Before Any Work Begins

First, know that sometimes improving clay soil can a difficult process. Please know that it takes skill, knowledge and often the use of heavy equipment to correctly remove surface soil, perform rough grading, prepare a proper subgrade, and to remove or work around in-ground sprinklers. 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.

It may be in your best interest to hire a professional if you have never done this type of work before or if extensive work is needed. However, many homeowners have done this successfully as long as they followed sound practices. At the very least, consult with a professional 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.

Tree location and tree roots need to be considered. Degree of slopes, foundations, percentage of rock, loss of topsoil from erosion, weather, use of equipment, and other factors must be considered. However, modest changes for improving clay soil can be performed when sound principles are applied. Again, if you are in doubt, always consult a local expert before you begin any work.

Considering if Soil Removal is Necessary

You will need to determine if the removal of any soil is 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:

• This may be obvious, but is you lawn surface the exact level as your home entry floor? In other words, will bringing in more topsoil place your lawn above your ground level floor?
• Is your home built on a raised concrete foundation? Determine if you have enough space to work with without removing any surface soil.
• Remember that additions of several more inches of topsoil over the roots of trees can cause damage to trees. The roots are in the position needed to get water and oxygen. The damage will often appear in the tops of the trees first. Severe cases can kill the tree. Trees get their oxygen from the soil and if too much dirt is applied, it could seriously reduce the amount of oxygen the tree is able to get.
• If soil removal is necessary, first call your phone company, electric company, and other utilities to mark any buried lines. In most states it is the law. Most states provide a service such as "dig-rite", or other service that will send someone out free of charge.
• You must consider how a rise in topsoil level will affect sidewalks, driveways, and in-ground sprinkler systems since, to a degree, these things are generally considered permanent fixtures in the lawn.
• When the top six inches of clay soil needs to be removed and replaced with topsoil, water will percolate through the topsoil and flow along the clay subgrade. (Explained in more detail below). Consider if there is anything that would stop the natural flow of water and cause it to pool below the surface. This may create problems you may have to fix later.
• Will the slope of your lawn be changing? The subgrade slope and topsoil surface slope needs to be the same.

Understanding the Subgrade

Unless you are experienced at this you should probably hire a professional. Here’s why. After the removal of six to eight inches of surface soil a subgrade needs to be formed before topsoil is brought in. With clay soil, the subgrade is often clay or whatever soil mixture is found after the surface is removed. This subgrade will need to be carefully rough graded forming the same degree of slope that the finished topsoil will be.

The most important thing: The slope of the subgrade will need to be sloping away from the house. 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 against the house where flooding or foundation problems can occur.

The subgrade needs to be as smooth as possible. This means no low or high spots, no deep tire tracks, no holes where large rocks were removed, etc. Low spots, tire tracks, and holes will collect water that could cause problems with the turf later.

Once the subgrade is formed correctly be sure to remove all the debris before bring in several inches of topsoil. Some contractors get lazy and will leave things on the subgrade to be buried by the topsoil later. In their mind it is a lot easier than hauling them away.

Problems that can occur with burying objects.

• “Fairy Rings” are circular patterns of mushroom growth that form as wood decaying fungi feed on buried wood. The mushrooms are the above surface fruiting bodies of the fungus where spores are released. The fairy rings can last for years and often cause dark green circular streaks where the contamination exists. Grass in the fairy rings tends to grow faster than the rest of the grass and the mushrooms can be unsightly.
• Large flat rocks, buried sheet rock, or other debris can cause spots in the lawn. They often resemble dry spots, dead spots, or diseased spots where the grass is struggling to stay alive. The spots will often be most severe in summer months. Where the rocks come to an inch or two from the surface, they give less room for grass roots and the rocks heat up damaging what roots are there.
• If you live in a rocky area you may need to use a rock rake to work over the surface. This will loosen any rocks and help drag them to the side for removal.

Applying Topsoil To the Subgrade

The weight of a 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 you help to avoid the high and low spots associated with settling soil.

You can also use this stage in the renovation process to install any drainage tiles, retaining walls large or small, sprinkler systems, install planters, or plant trees.

With your project of improving clay soil almost complete, the lawn is ready for seeding or sod.