Is Your Lawn Growing In Clay Instead of Topsoil?

With enough care, a homeowner could probably lay sod down on top of a large slab of concrete and get it to stay green. Of course, no one in their right mind would try this. And yet there are thousands upon thousands of people living in subdivisions who are just about trying to do the same thing.

All too often when a subdivision is being developed and massive re-grading is being performed, large amounts of topsoil are removed and sold at a high price for the rich topsoil that it is. Later, when it’s time to apply seed or sod to the landscape of a newly built home in such a subdivision, it will be applied to what is basically a subsoil. Unfortunately, all too often this subsoil contains a very high percentage of clay. Now mind you, clay has its benefits. Because it perks slowly, it will hold water and remain moist longer than a very sandy soil. Clay also tends to hold beneficial nutrients better than sand. However, between a heavy clay content and a very sandy content of the soil, there lies a much healthier content known as topsoil. Topsoil is ideally suited for growing grass, and in an ideal world your lawn would be growing in four or more inches of topsoil.

Topsoil contains extremely fine particles (such as those found in clay), very coarse particles (such as those found in sand), and - most importantly - lots of organic matter. Topsoil is very well-rounded and, as such, is perfectly suited for growing grass and many other plants. If you are trying to grow turf in soil that has too much clay or too much sand, you can (over time) make applications of topsoil and thus amend your soil, making it more suitable for growing turf.

There are a couple of things that will indicate you have a very high clay content in your soil. One is severe and persistent ponding after a heavy rainfall. Since the very tiny particles of clay do not allow water to drain through (or perk) very quickly, the water will stand on the surface for a long time. If the surface is sloped, another indication of high clay content after heavy rain is that the water will run-off quickly rather than soak in. One more indicator of high clay content in a soil is that once the soil has had most of its water dried out of it, it is hard and brittle - similar to concrete.

If you suspect that the clay content or the sand content of your lawn’s soil is too high, you can always apply topsoil. One dramatic way of doing this would be having large trucks deliver large amounts of topsoil and having this applied evenly all over your turf areas and then reseeding or restarting your lawn. This is NOT a method I recommend. I believe a much better approach would be to have just a few yards of topsoil delivered and dumped in an inconspicuous spot in your yard. Then from once a week to once a month, you can take a bit of this topsoil from the pile and scatter it throughout your lawn using a broadcast type spreader. It will be important to keep your pile of topsoil covered with a tarp or large piece of plastic so that when it is time for your to apply your topsoil it will be dry enough to fall through the hopper of your spreader. When topsoil is applied in this manner (small amounts on a regular basis), it will not destroy or damage your existing lawn.

Special Note: If you’re going to take the time, spend the money and go through the above amendment process in order to get more organic matter into your soil, then you should also be mulching when ever you mow. As I have stated in prior posts, mulching is one of the easiest and least expensive ways of putting organic matter back into the soil. Running a close second is applying compost, particularly if it is compost you have made yourself.

NEXT TIME: Your County Extension Office As An Information Source