The Blog

How to Improve Clay Soil with Compost and Amendments

Written by Minick Materials | Oct 22, 2025 2:24:25 PM

Soil is composed of three primary materials: sand, silt, and clay in different proportions. Even without having soil formally tested, it’s pretty easy to tell if your soil is high in clay content: maybe it doesn’t drain well, it compacts easily, or your plants don’t grow well in it.

Unfortunately, in many parts of the U.S., and especially in Oklahoma, clay soil is common. The good news is that there are ways to improve soil quality to support healthy root growth, drainage, and a looser structure. Compost and other soil amendments are great options that homeowners and professionals can use for short- and long-term soil improvement season after season.

Here, we’ll look at the characteristics of clay soil, the benefits of compost and other materials for countering the negative effects of clay soil, and how to start building better, more productive soil!

Understanding Clay Soil

Clay is made of fine minerals and sand that form tiny, dense particles. Handfuls of clay will compress when squeezed and hold that shape when you let go. Puddles tend to form on top of clay soil instead of absorbing it. Clay is fertile because it retains minerals; however, most plants have difficulty growing roots into it because it is dense and heavy. Roots also can’t get the oxygen they need in heavy clay, and they tend to become waterlogged because clay retains water. 

Many parts of Oklahoma have clay soil due to underground bedrock made of sandstone, siltstone, and shale that break down over time into tiny mineral and sand particles found in clay. The soil is also very high in iron oxide, which gives it its characteristic red color.

Why Compost Improves Clay Soil for Planting and Growing

If you have clay soil, the good news is you’re not destined to only grow in raised beds or containers; however, you will need to put in some time, effort, and above all, compost. 

Compost is made of decomposed organic material, like food scraps, plant waste, and sometimes animal waste. It is rich in nutrients, but importantly for clay soil, compost is an excellent source of organic matter. When mixed into clay soil, compost loosens the dense, clumpy structure so it crumbles, drains better, and is easier for roots to grow in. Compost is also naturally rich in beneficial bacteria and microorganisms that improve soil health.

Minick Materials carries several different compost products for amending clay soil, plus we offer soil amendments in bulk delivery and expert advice for transforming your clay into healthier, more balanced beds. 

Other Soil Amendments for Clay

There are several other soil amendments that benefit clay soils, including:

  • Sand: Improves drainage and texture, but must not be added alone to avoid creating a concrete-like mixture.
  • Gypsum: Loosens soil structure and adds calcium without changing pH. 
  • Mulch: Can be layered on the surface to prevent compaction and erosion; some options, like shredded bark, finely chipped wood, or fall leaves, can be mixed in.
  • Blended topsoil or specialty mixes: Adds targeted nutrients and organic materials; available in bulk.
  • Cover crops: Buckwheat, legumes, and some grasses are grown intentionally to pull up, turn under, and work into the soil. This releases organic matter, bulky plant waste, and nitrogen back into the soil as they decompose.

Step-by-Step Guide to Improving Clay Soil

Improving clay soil is a process, and you probably won’t fix it completely in a single season, or even a few. Don’t worry! The sooner you start, the sooner you’ll see lasting results and healthier plants. Here are our top clay-busting tips:

  • Test your soil annually. Soil tests look at texture and structure, as well as pH. Buy a DIY test or send a soil sample to your area cooperative extension office, such as the Oklahoma extension office
    • Ratios. If the proportions of clay, sand, and silt show more than 50% clay, the soil is considered heavy clay; however, problems frequently occur at lower concentrations, too. 
    • pH level. Clay soil typically has a higher, or more alkaline, pH value. Most plants and vegetables grow best in neutral soil, so your test results may include directions for lowering the pH with precise amounts of sulfur amendments or peat moss.
  • Apply compost for clay soil. Spread a generous layer of compost, 6 to 8 or more inches deep, on top of your soil. 
  • Add amendments. Evenly spread sulfur, peat moss, organic matter, or other targeted amendments in the quantities specified by your soil test results or a qualified expert
  • Blend thoroughly. Work compost and amendments into the top several inches to one foot of the soil with a pitchfork, spade, or tiller. 
  • Mulch. Layer mulch on the surface to protect against compaction and erosion.
  • Repeat. Add these steps to your regular spring yard and garden tasks to build long-term soil health, fine-tune nutrients, and maintain the improved structure and texture you’ve built.

Choosing the Right Products

If your goal is to fix clay soil in Oklahoma (or anywhere else!), it’s critical to blend in high-quality compost, gypsum, soil blends, and amendments. Find a supplier that specializes in the materials you need, and who can help you understand how to apply them correctly, such as the team at Minick Materials. 

We serve homeowners, professional gardeners, and landscapers with bulk ordering and delivery for larger projects (lawns, farms, landscapes). It’s more convenient than hauling bags yourself, and you can easily see just what you’re getting.

Clay Control Starts with Minick Materials

Clay soil doesn’t have to mean permanently poor growing conditions. Talk to our experts about the right mix of compost and gypsum for your soil. Adding compost and other soil amendments regularly makes soil healthier and improves its texture and structure, so lawns, landscaping, flowers, and veggies thrive.

Contact Minick Materials for all the products you need to transform your clay-heavy soil!