We’ve all got it — clay soil, that is
GREATER AKRON — Clay soil is a soil that is composed of mostly clay particles, and soil that consists of more than 50 percent clay particles is referred to as heavy clay. There is no doubt that Ohio was built on top of a huge mound of icky, sticky thick clay that becomes stone hard, cracks and crusts over when dry and nothing much likes to grow in it. If you are a gardener, you can relate, right?
Among other negatives, clay soil is also slow draining; it is slow to warm in spring; it heaves in winter; and it leans towards alkalinity. Clay soils are so compacted that the plant’s root system is unable to access essential oxygen required for growth. In contrast, coarse, sandy soils dry out rapidly and usually have a low level of fertility.
But overall, if I had my choice between a quick-draining sandy soil or clay, I’d choose clay. That’s because clay soil is actually a very dense, nutrient-rich soil. Because of its density, clay soil retains moisture well. The reason it is more nutrient-rich than other soil types is because clay soil particles are negatively charged. They attract and pick up positively charged particles, such as calcium, potassium and magnesium.
Still, you can’t grow plants successfully in clay soil without some help from organic amendments to loosen clay so that plant roots can breathe and access those nutrients.
It takes some work to improve soil, but it is well worth it and you’ll see the benefits right away. After that, you can continue to improve the soil with some annual maintenance.
If your bed has existing plants, dig them out and set aside the ones you wish to keep. If you are planning a new garden bed, plan to improve the entire planting area at the same time, rather than amending the soil only in individual planting holes.
If you amend only the individual planting holes before planting, you’ve basically created an underground flower pot that will restrict the long-term health and growth of the young tree, shrub or perennial that you have planted. When the plant roots grow enough to reach the sides of the earthen flower pot you have created, they will encounter the heavy clay soil that will take effort to penetrate. Count on it that the roots will decide to begin circling the earthen pot, rather than struggle to spread out into the surrounding original clay soil.
So, decide on the area you want for your new garden and measure it out. You will need to incorporate 6 to 8 inches of organic matter into the entire bed. Organic matter can be a mixture of any or all of the following: chemical-free grass clippings, shredded leaves, well-rotted manure, aged sawdust, peat moss and compost. First spread the organic matter evenly over top of the soil. Then mix the organic matter into the top 6 to 12 inches of soil. Use a rototiller or use a shovel to manually dig deep and turn over the soil. The garden bed will be higher than normal but will settle as time goes on and microorganisms get to work on transforming the soil. Once the garden is planted, it is a simple matter to add a top-dressing of organic matter each year to supplement the nutrients in the soil.
The garden can be planted immediately if you amend a garden bed during the gardening season, but I prefer to make these types of changes that can be somewhat unsightly to the garden in the fall.
Twenty years ago, I used this method to transform the heavy clay soil in my own garden: For three years each October, I mowed the yard with a grass catcher in place to capture grass clippings, as well as chop the leaves that had fallen from the trees. The contents of the mower bag were dumped in piles on my garden. I repeated this procedure throughout the month until I had collected enough clippings and leaves so that the garden was about knee deep in this mixture from one end to the other.
The last step before putting the garden to bed for the winter was to sink a shovel deeply into the soil and flip the shovelful of soil onto the clippings. I did this the entire width and length of the bed. When finished, it was a lumpy, bumpy mess. But by spring time, the freezing and thawing that occurs over the winter months had worked its magic on the garden to help break down those lumps as the organic matter decomposed.
It’s a good idea to collect a soil sample after about a year and have it tested for nutrient deficiencies and pH. The test results will let you know what you need to do to further improve the soil. Add organic fertilizers and/or soil amendments per the recommendations in the report.
Keep in mind that organic matter in soil also serves as food for earthworms, insects, bacteria and fungi, which all work together to transform the organic matter into soil nutrients and humus. In turn, these nutrients are made available to growing plants.
For details, call The Ohio State University Summit County Extension Hotline Tuesdays from 9 a.m. to noon at 330-928-4769, ext. 3, and request Bulletin SAG 17-10, “Inoculants and Soil Amendments for Organic Growers.”
Dayle Davis is a freelance writer and avid perennial gardener, with a B.A. in communications and course work in botany, geology and wildflowers. Davis is a master gardener emeritus under The Ohio State University’s Horticultural Extension.
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