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Back in 2016, my wife and I built a house on a couple of acres of what we felt could be transformed into a beautiful oasis. This was my first introduction to the challenges of clay soil.
Since moving in, I’ve tried a multitude of strategies to improve the quality of the soil in my yard. Topdressing with good soil should certainly be part of your strategy but where I’ve seen the largest improvement is through deep soil amendment.
Drilling holes and Infusing organic material deep into the ground throughout the lawn has proven to be the most effective means for truly improving the condition of clay soil.
First, let’s make sure we understand the typical approaches to improving clay soil and why they are only addressing part of the problem.
Topdressing Clay Soil: A Shallow Approach
The concept of topdressing a lawn with good soil is based in part on the root system of your lawn. By adding a nutrient-rich topdressing of soil, you can reduce thatch and build a better environment for surface root growth (source).
This approach has merit and certainly should be a part of your soil improvement strategy but it is not an end-all-be-all solution. The soil underneath is still compacted clay.
Plus, if you live on an incline as I do, a lot of that good soil will wash away with heavy rain. I’ve experienced this personally several times and it is very frustrating.
Core Aeration Improves Integration Of Organic Material Into Clay Soil
A common approach to overcoming the shortcomings of topdressing alone is lawn aeration. Throw away those spike lawn shoes, they are not effective. We are talking about true core aeration where small cores of soil are literally pulled from the ground.
When core aeration is followed by and combined with topdressing, you create holes where at least some of that good soil can work its way into the ground. This offers tremendous benefit over topdressing alone but it is still not the perfect solution.
Why? Because even with proper core aeration you are still only penetrating a few inches into the ground. The hard, compacted clay soil below will continue to cause issues.
It will resist water absorption (reducing facilitation of drainage during downpours) and will cause your lawn to brown during dry spells.
I know this because I have dealt with both of these issues regularly.
The Missing Ingredient To Amending Clay Soil – Deep Integration
Where topdressing and core aeration fall short is in their ability to improve the clay soil deep underneath.
A couple of years ago, I wondered beyond the path of conformity and began to experiment with an approach to soil improvement that I picked up from a local farmer.
Years before I had seen him in his pasture with his tractor, drilling into the ground with an auger. I asked him later about this and he explained that he dumps chicken manure and leftovers from his kitchen scraps in these holes.
He said that the clay soil we have in this area didn’t allow for enough nutrition in the grass for his cows.
The old farmer then pointed out several areas in the pasture where the grass was noticeably greener, noticeably healthier. He explained that those were the areas where he had drilled down and buried scraps and chicken manure over the years.
He also emphasized that these were the areas where the cows frequented the most, indicating that they were getting the nutrition they needed from these treated areas.
Drilling Down To A Solution
At the time we hadn’t yet built our house so I would say that at best I was amused. I pondered this for a few years and even read about gardeners who use similar techniques not only to improve the condition of the soil but to also improve drainage.
When we built our new home and I was faced with starting a lawn in red clay soil, I began thinking about the old farmer again. It took some thinking and a little research but I finally found just what I was looking for.
This is a 24-inch drilling bit specially designed for soil. It connects to a standard drill. It’s described use is for drilling into the ground to facilitate planting bulbs, etc. But I’ve found a much better use for it!
By drilling down deep into the soil, you can pull up a lot of clay and replace it with organic material like kitchen leftovers, coffee grounds, and of course plenty of carbon-rich browns such as dried leaves, twigs, and pine straw.
Here’s a close up of the business end of this device.
Best of all, you do can this in an existing lawn without making a huge mess of your yard. Yes, it does result in holes in your yard but I’ve found that once I get rid of the clay that it pulled up and fill the last two or three inches of the hole with good dirt, it’s hardly noticeable.
And it doesn’t take long before your grass starts growing back over it anyway.
Fast Lawn Recovery From Drilled Holes
Here’s a hole from just three weeks ago in my front yard. You can see that the grass is already beginning to grow back over it. You would never see it unless you were looking for it.
Here’s an area where I used this process last summer on a part of my back yard that has sod. Do you see that patch of deep green grass? That’s directly over the area I filled with organic material.
Here’s a closer look at the treated area. Notice the deep, rich green texture of the grass blades.
Compare that to the grass color and thickness of the area right next to it. You can see the treated area just to the left in this picture which I hope really helps to show the contrast.
I believe that part of the reason that this technique is so effective is that you aren’t just treating the symptoms and covering up the real problem. You are digging into the core underlying issue and correcting it!
By drilling down and filling the holes with organic material, you are literally changing the organic composition of your soil, a little at a time. This provides multiple benefits, including:
- Improved aeration and drainage immediately since air pockets are created between the materials. Water is able to drain through the soil horizons into more permeable layers (assuming the clay layer is not too deep).
- It also creates a food source within the soil that can attract earthworms. The worms then tunnel into the clay and deposit their castings, improving the soil around the area.
- Finally, you are creating opportunities for deeper root structure with nutrient-rich soil that can feed your lawn and maintain moderate moisture during dry spells.
What Organic Material Should You Use To Fill Drilled Holes In Your Soil?
When it comes to filling the holes, you have more options than you probably realize. Essentially, any organic material can be incorporated into your soil. Stay away from meat and dairy of course but fruit and vegetables that have gone uneaten and coffee grounds are mainstays of this strategy.
If it came from the soil, return it to the soil.
Shredded paper and small pieces of cardboard are also great to include. And as always, leaves and grass clippings. In fact, I like to give my yard a fresh mow before I add the last couple of inches of dirt to fill it up. This allows for fresh green clippings in the holes for some extra nitrogen. Then, I topdress the lawn, allowing the new soil to fill in and completely cover the hole.
Whenever in doubt, remember this: If it came from the soil, it can be returned to the soil. Nature will know what to do with it.
The Step-By-Step Approach To Drilling Holes to Improve Clay Soil
After attaching the bit to your drill, lean into it with a firm grasp as you begin drilling. Don’t push too hard, just apply steady pressure and let the drilling coil do the work.
If you hit a stump or large rock, move a few inches and try again. Your goal is to get at least 10 inches into the ground but whenever possible I like to get a full 20 inches of depth.
You can do this standing up at first but as you work the drill bit into the ground you will need to kneel or have something to sit on to prevent hurting your back.
When you finish drilling you will have a mound of removed soil around the hole. I recommend you get rid of this. You will not want to put any of the clay soil back in the hole.
I prefer to walk around the yard and drill as many holes as I plan to fill that day first, then come back and focus on filling.
Replacing Compacted Soil With Organic Material
With the holes drilled, you simply begin dropping organic material into them. Try to add an even mix of browns and greens. I find it handy to have a stick with me that I can use to push material deep into the hole as I go.
Fill the hole until it is 2 to 3 inches from the top. If you haven’t mowed yet, this is a good time to do it. Let the grass clippings fall into the hole. You can even rake some in if you want.
Finally, add some good soil. If you are planning to topdress your lawn, do it now. If not, get some quality soil and just fill the last two to three inches of the hole.
Spray a little water on it (not too much!) and that’s it. You can add a little water from time to time depending on how dry your yard is but you don’t need to saturate it. Dampness is good enough.
That’s all there is to it. Nature will take it from here. Now you can save up some more kitchen scraps and get ready to do it again when you are ready.
If you are interested in incorporating this soil improvement strategy in your yard, click here for the latest pricing on the 24-inch yard drill bit available on Amazon.
Make This In-Ground Composting Method A Part Of Your Comprehensive Lawn Care Strategy
Drilling holes in your yard and filling them with organic material is not a magic all-in-one solution. But it should be a part of your soil improvement strategy.
Should you topdress your lawn with quality soil or compost? Yes.
Should you aerate regularly? Of course.
But this is the part of the equation that is often left unaddressed: drilling down and literally beginning to change the very structure and texture of your soil by infusing nutrient-rich organic material.
Yes, it takes time but so does every soil amendment strategy out there. The difference with this approach is that you are truly making a lasting change in the quality of the soil, not simply treating the symptoms of poor soil quality and drainage.
Where would you rather invest your time? Treating the symptoms or curing the underlying cause?
I tend to test theories like this with a bit of skepticism. The truth is, I felt like putting organic material into my clay soil lawn was a good idea but I never expected the results that came from it.
You can literally stand in my yard and pick out the areas where I’ve drilled down and added raw organic material. The grass is a deeper green. It’s denser and clearly healthier. A thriving yard needs nutrient-rich soil and aeration to allow for root growth. This approach provides both.
I will continue this endeavor for as long we live here. Every year the soil will improve.
By all means, continue your current lawn care practices. Topdress, fertilize and aerate. But consider adding this approach of deep soil integration. Then you will truly have a complete and comprehensive soil improvement strategy.
To learn more about transforming your clay soil into a Thriving Yard, read this article on Improving Clay Soil For New Or Existing Lawns.