The Quick Trick That Makes It Easy To Know If It's Time To Aerate Your Lawn

Lawn aeration isn't exactly something you look forward to. Unless you're the sort of person who relishes the opportunity to change a car tire or spend an afternoon spreading mulch, dealing with aeration equipment is one of the worst fall maintenance jobs and is probably something like a necessary evil for you. But here's the question ... and it might be one that you will come to love ... Whether it's evil or not, is it actually necessary?

Fortunately, it's really easy to tell, in most situations. The main purpose of aeration is to relieve soil compaction, and one way to tell if your soil is compacted is to jam a screwdriver into it. Sure, there are other ways to do it, if you want to buy some equipment or involve a laboratory, but for most residential grass farmers, what you really want ot know is how easily turfgrass roots can penetrate the soil under your lawn, and the screwdriver test can usually tell you that, at least in broad terms.

Before we take a closer look, let's consider what we're trying to accomplish by abusing a tool in this way. It's usually not necessary to aerate on a regular seasonal schedule. Unless the screwdriver test, or some alternative, says otherwise, you can probably get by with the usual "cultural practices" that help keep your soil loose and root-friendly, like properly watering, fertilizing, and mowing. In fact, too much aeration can be counterproductive, leading to more compaction rather than less, as well as to general damage to your lawn.

The idea of the screwdriver test is to figure out how compacted your soil is by pushing a 4-to-8-inch screwdriver into the soil in a number of places and assessing how easy it is. For the sake of accuracy, you want to test soil that has had a good, soaking rain in the past 24 hours. Apply force evenly for every test, and determine if you're consistently hitting a compacted layer before your final depth.

What that final depth is depends on who you ask. Some say 4 inches is sufficient, while others recommend 6 inches, or even 8. (Agricultural testing can involve depths to 15 inches or more, far more than your lawn requires.) While a simple screwdriver is a common way to conduct this test, others have reliably used wire marking flags or even an electric fence post.

Of course, these aren't the most precise tests. Since root growth is believed to normally stop at around 300 psi of required pressure, you can use a soil penetrometer with a built-in pressure gauge, and it will tell you at what depth(s) that pressure becomes necessary. Compacted soil with enough pores and cracks will allow for meaningful root growth in spite of exceeding the 300 psi target. So, since there's a bit of guesswork involved in even fairly precise testing, why not give the simple screwdriver test a try first? Of course, this won't tell you anything about related issues, like the soil percolation rate, and note that this is different from calculating soil compaction for construction purposes, which is critical on a whole other level.