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Your Lawn Sinks When Walking On It (Why + What to Do)

Depositphotos 264612734 XL Your Lawn Sinks When Walking On It (Why + What to Do)

Just because your lawn seems spongy when you walk on it or you see water sitting in new places, don’t panic. It is probably not a sinkhole opening up.

Your sinking lawn is likely a result of too much thatch, poor drainage, soil problems, overwatering, heavy foot traffic, or several other issues. All of these problems can be fixed with the correct lawn care. Fairly easily and without too much expense.

Once you determine the reasons your lawn is sinking, plan on fixing the problems quickly. A spongy sinking lawn can lead to bigger problems.

Here is what you need to know and do to repair the causes of a sinking lawn. 

Nine reasons your lawn sinks when walking on it. And how to fix them.

9 Causes of a Sinking Lawn – And How to Cure Them

Some of the common reasons for your lawn sinks are listed below, along with the repairs you need to make.

Poor Drainage

Too much water and poor drainage is probably the leading cause of sinking lawns. Grass gets waterlogged by rain, overwatering, and accidents like broken pipes or hoses left running.

Drainage is the flow of water in your yard. Most yards are sloped away from the building to prevent foundation water problems. If the gentle slope is continued to the edge of your property or a French drain your yard should be draining well. In addition to sinking into your lawn, you may begin to see standing water–usually in low spots of the yard. 

Solve the Problem

If there is water pooling near or around your house, re-grading your yard is necessary. A fairly common grade is 5%. A half-inch slope every foot. Re-sloping the entire yard is usually not necessary. Take note of any low spots and add topsoil to improve water flow.

Another option might be to add a French drain to a low area. French drains are perforated pipes buried in gravel to pick up and move water to a different location. Sometimes they take water to a buried storage tank or the pipe will daylight (emerge from underground) at a lower location to flow away overland.

Another option is to landscape a grass swale through and from the low areas to drain the water off your lawn. (See North Carolina State University for more details about grass swales.)

Overwatering

Overwatering will eventually have water sitting in any depression in your lawn. The wet spots are prone to sinking as you walk across them or when you mow your lawn.  Overwatering may also cause entire yards to sink because the soil will be compacted. Compacted soil also makes for sickly-looking lawns because fertilizer can’t get down to the roots.

Depositphotos 190910476 XL 2 Your Lawn Sinks When Walking On It (Why + What to Do)

Solve the Problem

Buy an inexpensive soil moisture meter to tell you when you need to water. Packs of 4 meters are available for under $20.00 allowing you to get real-time readings from different locations. Water your lawn accordingly.

Leaking Irrigation System

Underground irrigation systems can leak. If a pipe breaks and no one notices, the water pouring out of it can wash away a lot of soil in a hurry. A cracked pipe will create a wet soft spongy spot in the yard over time.

Driving the mower over the spray head can have it spewing water when it turns on. So can kicking it or walking on it. Not to mention the “timer not turning off” problem for the weekend you are away.

Solve the Problem

  • Broken Pipe. A broken pipe spraying water underground for a couple of hours is pretty obvious. You will have a junior-grade lake on your lawn. Dig up the pipe and replace the broken section. Or call an irrigation company to fix it.
  • Cracked Pipe. Cracked underground pipes are difficult to spot. Until you sink into a wet spot that should not be there. You may have to do a little exploring to find the crack. And get parts to fix it.
  • Broken Heads.  Make sure the heads work properly when they turn on.
  • Timer Problem. Check your timer regularly. Turn it off when you are away if you don’t trust it.

Soil Erosion

Soil erosion can be caused by defective eavestroughs, short or non-existent downspouts or extensions, neighbor’s water runoff, or heavy rain and a natural waterway through your property.

Solve the Problem

  • Install eavestrough properly sloped. Extend downspout runoffs to 10′. Drain them onto splash pads.
  • Construct a French drain or grass swale (See North Carolina State University for more details about grass swales.) to accommodate heavy runoff–from the neighbor or anywhere else.

Excess Thatch Buildup

Thatch is the buildup of non-decayed organic matter in and on the lawn. Thick layers of thatch make your lawn feel very soft when you walk across it. Thick thatch also prevents the effective use of fertilizers and promotes weak root growth. For more details on thatch please see Oklahoma State University Department of Extension “Thatch Management in Lawns”.

Solve the Problem

Use a dethatcher or power rake to remove the thatch from your lawn

Note: Your lawn will look pretty ragged after you dethatch it but the long-term improvement is well worth it.

4 Additional Reasons Why Your Lawn Sinks 

Things that cause sinking lawns can seem endless. Here are a few more.

  • Soil Quality. Clay soil will sink as it compacts. Adding organic matter will improve drainage, and absorption, and prevent further sinking.
  • Aeration. Compacted soil leads to a sinking lawn. It also suffocates grassroots preventing them from growing and improving the soil. Aerating your lawn regularly allows fertilizer and water to get deeper into the soil, improving grass growth.
  • Mowing. Grass that is too long is easily damaged by people walking on it. Too short may cause stress during droughts. Also more weed growth. The ideal length for most grasses is 2 – 3 inches.
  • Decaying Trees. You may have dead trees or roots under your lawn which may collapse as they decay creating soft or low spots on the lawn. You can either dig them out or continue to add topsoil as they sink. Reseed the topsoil.

End Notes

Most healthy lawns do not sink very much. Unless you have some real serious problems like eavestroughs or neighbors, filling in the odd low spot should keep your lawn from sinking. Add topsoil mixed with a little manure and peat moss. Make sure to put on a little extra because it will settle. Sprinkle seeds and fertilizer on the fresh dirt and water well.