How to Amend Clay Soil for Organic Gardening

Some gardeners do not need to make much of an effort to amend their soil, but for others, especially those with clay soil, there is a lot of groundwork to be done before planting can happen. Clay soil is far too dense and compact to allow the roots of plants to receive the oxygen and nutrients they need. By adding organic matter to the soil, you can add healthy, soil-dwelling microbes, improve oxygen and water flow, and discourage compaction.

Difficulty: Moderate

Instructions

Things You'll Need:

• Trowel
• Soil test results
• Decomposed plant materials (compost)
• Rototiller
• Wheelbarrow
• Shovel
• Pitchfork
• Rake

1. Have your soil tested by the local county Agricultural Extension Office. The results give you an idea of the specific nutrients your soil lacks.

2. Form a homemade compost pile with last fall's leaves, spent mulch and kitchen scraps. Make sure it is thoroughly decomposed before you add it to your soil. Avoid using compost if you recognize items in it. Good compost is dark and crumbly with a fresh, loamy aroma. Alternately, purchase commercial bulk compost from a home and garden store.

3. Till the soil to about 8 inches deep. Avoid working with the clay when it is wet. Ideally, it should be a little moist.

4. Spread a 2-inch layer of organic soil amendment (compost) on top of the soil.

5. Work the organic soil amendment into the soil, using a pitchfork and rake to break up clumps of clay. Work the top layer of soil until it is well-mixed, smooth and crumbly.

6. Add a second 2-inch layer of organic soil amendment and any necessary nutrients (fertilizer, lime) indicated by the soil test results. Work this into the soil thoroughly. Aim to use roughly 25 to 50 percent organic soil amendment in your garden.

Tips & Warnings

• Avoid adding peat moss, sand, gypsum, fresh manure, fresh wood chips or sawdust to your clay soil. These items are not likely to improve the soil's condition for planting.

References

• North Carolina State University-North Carolina Cooperative Extension Service: Amending Soils; 2007