Soil compaction is the primary reason you want to aerate your lawn. You can determine if your lawn needs aerating by looking for the visible tell-tale signs of compaction or by testing the force required to penetrate the soil using a penetrometer. Either way, aerating your lawn to reduce soil compaction is important whenever needed. So, let’s take a closer look at how to tell if your lawn needs aerating and what tests and methods you can use.
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How to Tell When a Lawn Needs Aerating (My Overview)
Lawns that are suffering from soil compaction typically show signs of poor health. For example, a lawn suffering from soil compaction could have visible issues such as hard soil, thinning grass, loss of blade color, uneven grass growth, shallow root growth, and standing water. These symptoms typically occur once the soil compaction is close to or exceeds 200 PSI of penetrative force which can be confirmed using a penetrometer.
Problems Caused by Soil Compaction
Soil compaction and aeration are essential lawn care tasks that many homeowners overlook. Unfortunately, dismissing them can lead to a suffering and unhealthy lawn. Here are the main issues your lawn will face if you don’t aerate compacted soil.
- Reduced Water Absorption
- Limited Nutrient Access
- Limited Nutrient Intake
- Restricted Air Exchange
- Poor Root Growth
- Reduced Drainage
Visible Signs of Soil Compaction (What to Look Out For)
The best way to tell if your lawn needs aerating is to keep an eye on it. Here are several visible signs to look for that signify your lawn needs aerating. Let’s take a closer look.
Hard Soil Beneath Your Lawn
Soil compaction results from the soil being compressed by its weight or by above-ground forces such as foot traffic or heavy equipment such as a lawn mower. The compressed soil dramatically reduces vital resources from reaching the roots of your lawn, leading to several issues.
Thinning Grass & Patchy Grass
Soil compaction restricts air, nutrients, and water from reaching your lawn roots, limiting root growth. Once this happens, the roots of your lawn will die and cause your lawn to die. As this happens, your lawn will progressively become thinner and thinner and appear patchy.
Loss of Color
Once your lawn can no longer receive the nutrients it needs, you will notice a loss of color. This is mainly due to a lack of nitrogen. Excessive soil compaction can even restrict the effectiveness of newly added fertilizer to a lawn. So, if you notice fertilizer has no effect on your lawn, you are likely dealing with soil compaction.
Uneven Growth
Usually, soil compaction is present in different amounts around a yard. For example, areas with a lot of foot traffic, such as a pathway, will be more compacted than areas with very little foot traffic. This means you are likely to notice uneven growth across your lawn. The path will have stunted grass, whereas the open areas with little traffic will be much healthier.
Shallow Root System
Depending on the grass type, roots normally grow from a few inches to a few feet deep. So, if you dig into the ground and find that your roots are shallower than expected, soil compaction is likely the cause.
Standing Water
Last on the list is standing water on your lawn. If your lawn usually drains after watering or rain, then this is a sign that you have good drainage. But if the water starts taking longer and longer to disappear, this is likely due to soil compaction.
Testing Soil Compaction
One thing to be aware of when it comes to identifying soil compaction is that many of the symptoms are also symptoms of other issues. For example, loss of color in your lawn could be down to the lack of feed and fertilizer, a patchy lawn could result from disease, and standing water could be down to over-watering. So, to confirm soil compaction, it’s best to conduct a test. So, let’s take a closer look at how to test your lawn’s soil.
Penetrometer Testing
So what is a soil penetrometer? It’s a spike that you push into the ground to measure the force needed to penetrate the soil. These devices have PSI gauges that display the force used as you drive the spike into the ground. So if the gauge stays between 0-200 PSI, your lawn is good, but any higher means your soil is compacted. A reading higher than 200 PSI is classified as “Root Restrictive” soil compaction and means your lawn will be affected.
To use a penetrometer, you only need to drive the tool into the ground and keep an eye on the gauge. Depending on your lawn’s size, you may want to test several areas to understand the bigger picture. For sections with higher compaction, you might need extra passes with your aerator or choose a more efficient aerator, say core aeration vs. spike aeration.
So where do you get hold of a soil penetrometer that isn’t going to break the bank? You might find them in the box store or specialist landscaping suppliers, but I found that online has more choices and better prices.
My preferred soil testing tool: AgraTronix 08180, Soil Compaction Tester Made in the USA
Alternate Testing Methods
If penetrometer testing sounds a bit much, then other options are available. For example, you could determine if your soil is compacted by seeing how much effort it takes to drive a long screwdriver into the ground. I have used this method in the past, and it works to some degree. But without an actual PSI gauge, it’s complete guesswork and easy to misjudge. So I personally keep a penetrometer on hand.
Check out my 5 methods for testing soil compaction on your lawn.
Lawn Aeration Frequently Asked Questions
Lawn aeration tends to raise many questions and concerns when you’re first starting out with the topic. I’ve compiled a few of the common questions people ask me when they want to add lawn aeration to their lawn care program. Let’s take a look.
| QUESTION | ANSWER |
|---|---|
| When should you aerate a lawn? | Aerate when your lawn is actively growing. |
| How often should you aerate a lawn? | Twice a year during spring & fall. |
| What do you do before aerating a lawn? | Mow, then water to soften the soil. |
| What do you do after aerating a lawn? | Overseed if needed and fertilize. |
| Can aeration hurt your lawn? | Yes, if done excessively. |
| How do you avoid soil compaction? | Limit traffic on your lawn. |
| How deep do you aerate a lawn? | 0-6 inches (The deeper, the better). |
| What tools do you use to aerate a lawn? | Manual, powered, & towable spike & core aerators. |
