How to Compost Clay Soil


Clay soil is a heavy soil that compacts easily due to the small particles that pack together. This soil type is unable to properly grow plants or grass unless amendments of organic matter are added to lighten the texture, decrease compaction and increase the drainage and nutrient properties. Begin amending clay soil in the fall so the composition changes enough to allow for planting in the spring. The quality of clay soil will improve in two to three years with regular maintenance.

Step 1

Estimate the type of soil present by placing about 1/2 cup soil in your hand and adding a small amount of water and knead it into a soil ball.

Step 2

Create a flat ribbon of soil by pressing the ball between your pointer finger and thumb. A clay loam soil breaks at 1 to 2 inches while a clay soil creates a 2-inch or longer ribbon.

Step 3

Add 4 to 6 inches of organic compost to the top of a clay loam soil and 6 to 8 inches of organic compost to the top of a clay soil. Till the compost into the soil to a depth of 10 to 12 inches to break the heavy soil apart and increase the organic matter. Let the soil rest for a minimum of two months.

Step 4

Contact your county extension office to have a full soil test completed on the area. The results of the test will give recommendations for nutrient amendments.

Step 5

Take 10 soil samples throughout the amended area and mix them together. Measure 2 cups of soil and place it into the sample bag for testing. Follow the package instructions for submitting the sample for testing.

Step 6

Add fertilizer to the soil based on the recommendations provided with the soil test results. Apply an organic fertilizer if possible as the nutrients will stay in the soil longer and it will require fewer applications.

Things You'll Need

  • Water
  • Organic compost
  • Tiller
  • Shovel
  • Soil test kit
  • Organic fertilizer


  • North Carolina State University: Amending Clay Soils
  • University of Minnesota: Amending Soils for Perennial Beds
  • Fine Gardening: Improving Clay Soils
Keywords: amend clay soil, plant clay soil, compost clay soil

About this Author

Jennifer Loucks has over 10 years of experience as a former technical writer for a software development company in Wisconsin. Her writing experience includes creating software documentation and help documents for clients and staff along with training curriculum. Loucks holds a Bachelor of Science major from the University of Wisconsin - River Falls specializing in animal science and business.