How to Break Down Clay Soil Fast for an Auger

With the right techniques and tools, you can break down clay soil fast and make post hole digging much easier.

In this article, we’ll cover some tips and tricks for breaking down clay soil fast for post holes. 

Break Down Clay Soil Fast
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How to Break Down Clay Soil Fast for an Auger

If you’re planning on installing fence posts or any other structures that require digging post holes, you may have encountered the challenge of working with clay soil. Clay soil is known for being dense, sticky, and difficult to dig through, making it a frustrating obstacle for many DIY projects. We discuss many methods you can try to break down clay soil fast below.

Why is it so Hard to Use an Auger in Clay Soil

To effectively work with clay soil, it’s important to understand its characteristics. Clay soil is made up of very fine particles that bind together tightly, creating a dense and compacted soil structure. This makes it difficult for water to penetrate and for plant roots to grow. Clay soil typically has poor drainage, which can lead to standing water and soil erosion. 

When digging post holes in clay soil, you may encounter several challenges. The dense soil structure can make it difficult to penetrate with a post hole digger or auger. The soil may also stick to the sides of the hole, making it hard to create a clean and even hole. However, there are several techniques you can use to break down clay soil fast and make post hole digging easier. 

How to Break Down Clay Soil Fast

Here is our recommended ways to try and break down clay soil for an auger. You will probably have to use more than one because clay soil is one of the toughest soil conditions to deal with when drilling post holes.

  • Gypsum for Clay Soil
  • Clay Soil Treatment (Liquid Gypsum)
  • Water
  • Choosing the Right Auger
  • Using Proper Technique

What Chemical Breaks up Clay Soil : Using Gypsum for Clay Soil

Is gypsum the best way to break down clay soil? Gypsum works by attracting clay particles together, which helps to loosen the soil and create better air and water flow. It also adds calcium and sulfur to the soil, which can benefit plant growth. 

Using gypsum to drill post holes in clay soil can be helpful in some cases. Gypsum is a powdered clay soil treatment that can improve soil structure and reduce soil compaction. When added to clay soil, gypsum can help break up the soil particles, allowing water to drain more easily and reducing the likelihood of soil becoming compacted around the post.

To use powdered gypsum for drilling post holes in clay soil, you can mix gypsum into the soil before digging the hole. A typical recommendation is to add about 20 pounds of gypsum per square foot of soil. Alternatively, you can apply the gypsum directly to the bottom of the hole before setting the post.

To use gypsum, spread a layer of it over the soil surface and mix it into the top few inches of soil. Be sure to follow the manufacturer’s instructions for application rates. 

Gypsum for clay soil may not be a complete solution for drilling post holes in clay soil and you might need to use gypsum plus one or more of the other methods here to break down clay soil fast for an auger.

Does Water Loosen Clay?

Clay soil can be difficult to dig through when it’s dry, so wetting the soil can make it easier to work with. Water helps to soften the soil and reduce its density, making it easier to penetrate with a post hole digger or auger. Additionally, wet soil is less likely to stick to the sides of the hole. 

To wet the soil, use a garden hose or sprinkler to saturate the soil surface. Be sure to avoid overwatering, as this can lead to soil erosion and standing water. 

Choosing the Right Auger for Drilling in Clay

When using a power auger in clay soil, it’s important to choose the right auger attachment. Augers come in different sizes and shapes, and the right one for your project will depend on the size and depth of the holes you need to dig. 

For clay soil, a spiral auger with a narrow diameter may be more effective than a wider auger. This is because the narrow diameter can penetrate the dense soil more easily, while a wider auger may struggle to dig through the soil. 

Proper Drilling Technique for Working with an Auger

If you’re planning to put in a much longer fence line, soften the soil by digging pilot holes 6 to 10 inches deep then fill each with water from a garden hose. Allow the water to percolate down through the soil before attempting to dig out the hole using a post hole digging shovel, also called a clamshell shovel.

To make digging the pilot holes easier, use a spade shovel. It will slice through grass and clay more easily than other shovel types. Place the soil you dig up on a tarp so it will be easy to backfill the hole with and carry off the excess. 

When using a power auger in clay soil, it’s important to use proper technique to ensure safe and effective operation. 

First, stand firmly with your feet shoulder-width apart and hold the auger firmly with both hands. Keep your fingers and clothing away from the moving parts of the machine. 

Next, slowly lower the auger into the soil while keeping it level. Avoid jerky movements or pushing the auger too hard, as this can cause the machine to become stuck or damaged. 

As the auger digs deeper into the soil, you may need to lift it up periodically to remove soil from the hole. Use a shovel or trowel to remove the soil and clear the hole. 

Finally, once you’ve reached the desired depth, slowly lift the auger out of the hole while keeping it level. Be careful not to hit any obstacles or damage the hole. 

Other Clay Soil Treatments to Break Down Clay Soil Fast

Another way to break down soil fast is another version of gypsum. Liquid clay breaker is actually liquid gypsum. You can find many different brands, sizes and types HERE. Liquid gypsum is a concentrated version of the powdered formula we talked about above. It’s a great way to soften clay soil quickly and efficiently.

Tools You Need to Break Down Clay Soil Fast

On top of having an earth auger, you will need a few extra tools on hand to make sure the job gets done. 

You will need a shovel to start your hole, a wheelbarrow for the extra dirt, a digging bar to chop away at roots, dislodge rocks, and working at the clay soil.   Some folks prefer a different kind of digging tool called a Root Slayer Shovel. While it’s made for roots, it can really help with clay soils too.

You might also need a clamshell digger to get rid of the dirt at the bottom of your hole or to dig deeper, past the limits of your auger machine.  The best tool we recommend for digging in clay is a digging bar (and the other tools listed below).

Best Way to Dig Hard Ground By Hand

We have many detailed posts on how to use post hole augers to dig holes and even which ones are the best to buy for the job, please follow the links below for more information.

Best Tool for Digging In Clay

Digging Bar (Landscape Bar) 


digging bar is an essential tool here.  In our opinion, it’s the best tool for breaking up clay soil (or any kind of tough soils).

With clay soil being so difficult, you will have to use more elbow grease than when drilling in easier soil conditions. This take extra labor and time.  But you can’t break down clay soil without using a TON of elbow grease. 

Warning: Call Before You Dig! 

You never know what is underneath your top soil.  You could have gas and water lines, power, just about anything.  Don’t take any risks.   

Always give yourself enough time to find out what is underneath the areas you are planning on digging and call 811 to connect with your local utilities services for full details. 

Also, a little know fact here, you will want to make sure that your tetanus shots are up to date before digging around in the dirt.  Apparently, you need them updated every 10 years. 

Make sure that you have all your safety gear on hand which includes glasses, hearing protection, gloves and steel toed boots. Also wear tight fitting clothing to avoid having your clothes get caught up in the auger.

Remember to shred up the sides of the holes you’re drilling so any roots can penetrate the soil and so that there is a more textured surface for your fence posts.


How to break up clay soil for an auger will require you to use a few of the techniques above and a lot of elbow grease. Using a power auger in clay soil can be an effective way to dig post holes quickly and easily. However, it’s important to choose the right auger attachment, prepare the soil properly, and use proper technique. With these tips and tricks, you can make digging post holes in clay soil a breeze. 


What is a clay soil?

Clay soil is a soil type that contains a high percentage of fine mineral particles, such as clay, silt, and sand. It has a sticky texture when wet and can become hard and compacted when dry.

Why is it important to break down clay soils?

Clay soils are often difficult to work with as they can be hard to dig or penetrate. Breaking down clay soils is important to create a better growing environment for plants and allow for better drainage and aeration.