Tips for working with clay soil

Our part of the state is heavy in clay soils, literally. If you have clay for your garden, you know exactly what I mean. Clay soil is hard to work with due to its characteristics.

Clay has the smallest particle size of any soil type, which means a large quantity of clay particles exist in a relatively small space, eliminating gaps that would be present within other soil types. Clay’s dense structure and large water-holding capacity creates poor drainage and prohibits good root penetration. It can become so compacted that it deprives roots of oxygen. This soil type takes longer to warm up in the spring. Clay contains very little organic material and often lacks nutrients essential for plant growth and health. Some clay soils may also be alkaline because they are heavy with minerals, so the pH level may need to be adjusted before planting.

Because I can’t plant everything in my three raised beds, we still plant items like corn, squash and potatoes directly into the ground. Our garden suffers from all of the above ailments. The soil is cold well into spring and it doesn’t drain well despite the fact that is on a slope. The soil is heavy and turns to concrete after it rains, and the only thing that grows readily in it are weeds.

Clay soil can be amended to compensate for some of its problems. There are two broad categories of soil amendments – organic and inorganic. Amendments can improve drainage, aeration, soil texture and structure and the workability of the soil. Organics, such as peat moss, compost, sawdust, wood chips and manure are all from something that was alive. Inorganic amendments, such as vermiculite, perlite and sand, have either been mined or are man-made.

Over the years we’ve added most of the organics to our garden and some sand. Our biggest mistake has been not putting enough on at a time. Large amounts must be used before results are seen. Ideally, three to four inches of organic matter should be applied, along with one to two inches of coarse sand (fine sand, when added to clay, tends to make a concrete-like product). The amendments then need to be incorporated into the top six to 10 inches of soil. Depending upon the organics used, some nitrogen fertilizer many be needed to assist with the decomposition of the organic materials so that the plants don’t experience a temporary nitrogen deficiency.

Remember, this is an on-going process and you aren’t going to turn your clay into loam in one growing season, but improvements can be made. We add soil amendments all year long – leaves and a cover crop in the fall, manure through the winter and grass clippings and other mulches during the growing season.

Regardless of your soil type, the best place to start is always a soil test. It will tell you what you already have, so you know what to do next.

Lisa Crock is district program administrator with the Muskingum Soil and Water Conservation District. She can be reached at 740-454-2027.