Causes and Cures of Compacted Soil

Compaction results in turf tearing, injury, thinning, and even death from crushed leaves, stems, and crowns. Your lawn is meant to be used, but maybe you have used it excessively. Too much traffic leads to creating compacted soil. As tires roll and you step on the grass, the soil below becomes denser and denser.

While the other symptoms may be evident, compaction occurs out of sight. When the soil no longer has that big pore space, it can’t transport nutrients, water, and air that grasses require. Hence, the grass suffers and plant growth is limited.

4 Causes of Soil Compaction

There are four ways that turf managers and homeowners cause their dirt to pack very tightly:

1. Over-Tilling

Does your soil appear like an alligator’s skin? You may have tilled it excessively. Making a few passes with a tiller breaks down the preferable clumps of little aggregates that let water and air pass through, promoting root growth. It’s an indication of over-tilled soil if water ponds up and leaves behind a straight pattern of cracked soil. 

2. Working on Very Wet Soil

Avoid working on the soil when it is too wet, because that can also make it overly compact. Before tilling the turf or garden area in spring, take a handful of soil and press it into a ball. Then poke it. It must crumble. If it doesn’t, the soil is excessively wet.

3. Mixing Sand Into Clay Soils

Adding sand to clayey soil is a wrong move. Adding sand to clay forms a compact mass that’s similar to concrete. You can loosen the soil with organic matter like peat moss or compost.

4. Compressing Soil WIth Weight

Vehicles or heavy machinery parked or driven over an area, rebuilding or home construction— even heavy frequent foot traffic can compact soil. A riding mower’s tires that run over an area frequently may be responsible.

Cures of Soil Compaction

Listed below are some cures for compacted soil that you can implement:

1. Traffic Control

Riding lawn mowers, golf carts, cars, bicycles and foot traffic all compact soil to some extent. Controlling the when, what, and where of that traffic can shield your soil.

Appropriate operation of motorized vehicles makes a difference. Avoid quick starts and stops and sharp turns. Don’t drive on your lawn when it’s too wet. Irrigation should also be timed so the topsoil isn’t too wet when you’re expecting heavy traffic on your lawn.

2.  Dealing With Preferred Tracks and Shortcuts

Maybe your lawn experiences frequent traffic in the same spot, such as a shortcut to the bus stop for neighborhood children. That can become a path of bare dirt that can lead to more  compaction and stress. Those trails occur where pedestrians find the shortest route from A to B avoiding the sidewalks.

However, you have options even if that desired path ends up in an undesirable place like your lawn. Shrubs and trees can direct traffic. Ornamental trees or shrubs can be kept instead of fences. You may want to go ahead and make it permanent with mulch, pavers, or wood chips.

If that’s out of the question, compaction issues can be reduced. Add some coarse sands or other materials such as calcined clay where that traffic happens.

Your lawn itself can also help end compaction. Dethatching turf and cutting higher can help absorb some of the pressure and keep it from compacting the soil.

3. Core Aeration

Lawn aeration is the best method to deal with compacted soil. Both hollow-tine and solid-tine aeration are good, but hollow-tine core aerating is the more helpful option.

A pitchfork inserted into the ground and pushed back and forth may be sufficient for a single small area of light compaction. For bigger turf areas, you will require an aeration machine. The first choice is a core aerator, a machine that compels tines into the soil, tugging plugs of it out. That makes gaps in the lawn for the root system to grow deep down. Timing is everything when it comes to appropriate aeration. 

If you want your turf to recover well, aerate when its best growing season is going to arrive. Warm-season grasses can be aerified beginning in late spring through late summer. Cool-season grasses are best aerified in early fall or early spring. Slicing and spiking are two other ways, but they don’t really remove any soil from the lawn. Therefore, slicing and spiking can really compact the soil further.

To learn more about aeration, read the article ‒ What is aeration?

4. Add Topdressing after aeration

Topdressing after aeration can assist in the long run. Topdressing is just adding a small layer of compost, sand, or a mix of the two over the top of your lawn. Topdressing will help even small areas, can enhance drainage and restore microbes to help manage with future thatch buildup.

Simply rake over the exposed plugs if you used a core aerator. Breaking them up changes them into top dressing. Be vigilant about using a topdressing that is very different from your base soil. The best choice is topdressing with compost, since the soils don’t have a lot of organic matter. Adding that material can help the soil hold air and water better. Whichever you select, be cautious not to apply excessive topdressing for your long-term lawn care.

Excess material can make a layered soil and lead to the same issues you had with compaction in the first place. Whatever the reason, once you have aerated and top dressed, your soil must be able to breathe again and your grass will thank you for it.

How To Identify Compacted Soil?

Generally, home lawns experience soil compaction with regular, frequent pressure like parking a car on the lawn. You may have a dog in the backyard that has a path that it runs over and over again.

Riding lawn mowers can also be responsible, but only once or twice a week over the turf is not enough by itself to leave you with excessively compacted soil. It’s a larger problem for public spaces like ball parks and fields, which experience intense traffic. However, homes aren’t spared.

What Compaction Does to Your Soil

Compaction is responsible for damaging the soil structure. And that’s unpleasant news for your lawn. Most compaction occurs in your lawn’s root zone, the first two or three inches below the soil surface and eventually soil density increases.

Air can’t move through it, leading to a buildup of carbon dioxide and other gasses harmful to grass roots. Water can’t permeate either, raising runoff and reducing water infiltration in the soil and ceasing water uptake by the grass roots. Temperature highs and lows can become maximum. And there is more open space down there than you can imagine.

Your Grass Requires Wide Open Spades

Healthy soil contains pores, leaving space for air, beneficial earthworms, and grass roots.

Half of a healthy soil’s composition is pore space. Very dense soil hinders roots from getting to the nutrients, water, and structural support they require.

Compaction also brings numerous other issues. First, low shoot density promotes the invasion of weeds and disease activity.

The low rate of nutrient intake means an increased fertilizer schedule to keep your lawn healthy. However, that can make a bad situation worse, as the issue isn’t the absence of nutrients but the root’s inability to soak them. Providing nitrogen can further lessen the turf’s rooting ability.

For the same reason you need to fertilize more, you may need to irrigate more. And with the increased stress, your grass will become less resilient to environmental factors like drought, heat and cold.

Warning Signs of Soil Compaction

Healthy moist soil (above) develops clumpy mass when moist, compared to dry compacted soil (below). Soil compaction occurs more often in the spring when conditions are wetter and heavy rains more persistent.

Check out for places where weeds have started to take over. Some types of weeds, like goosegrass, grow better with compacted soils. At times that weedy patch is an indication that the soil below is compacted.

Some grasses such as Bermuda are hardy and tough when it comes to compacted soil, but even Bermuda will not be as happy as a weed in those conditions.

It can also be an issue for other plants, such as trees. People may notice a declining tree in their yard but not think the issue is compacted soil hindering the plant roots from their favored shady parking spot.

In conclusion, soil compaction is caused by over-tilling, working on very wet soil, mixing sand into clay soil, and compressing soil with weight. Cures of soil compaction include ‒ traffic control, dealing with preferred tracks and shortcuts, core aeration, and adding topdressing after aeration. Implement appropriate cures for your lawn to eliminate soil compaction.

Contact the experts of Eden today to help you eliminate soil compaction from your lawn and suggest ways to prevent it.