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what is topsoil made of

What Is Topsoil Made Of: A Gardener’s Guide

Topsoil: it’s the nutritious bed in which plants grow and thrive. But what is topsoil made of, exactly? If you’ve ever wondered that exact question, you’re in luck. We’re going to answer that question and more below by explaining everything you should know about topsoil.

At A Garden Patch, we love to help people learn all about the joy of gardening. With our GrowBox planter, you can grow healthy plants with no guesswork involved thanks to our Nutrient Patch™, which ensures correct spacing and automatically fertilizes your plants. Plus, we offer helpful accessories to make gardening even easier, like Jobe’s Organic Fertilizer and the GrowBox Support Cage.

Now, let’s get started learning more about topsoil!

What is Topsoil?

Topsoil is the uppermost layer of soil (~ 2” to 10” in depth) and contains a mix of water, mineral particles, air, organic matter, and microorganisms. So technically, the top layers of earth or any type of dirt can be considered topsoil.

You may think that the top soil layer doesn’t do much besides providing ground for you to walk on — but that’s just not the case. In fact, topsoil is where the most important actions occur to stimulate plant growth, like nutrient delivery, ventilation, etc. To put it simply, it’s where all the magic happens!  

You can identify topsoil by evaluating its composition and texture, although it varies by geological location. The most common topsoil types include:


Clay topsoil is a heavy, dense soil that isn’t ideal for gardening, as it lacks the proper drainage and aeration necessary for growing plants.


Loam is a medium-textured topsoil that consists of silt, sand, and clay. It’s dark, can hold its shape, and is chock-full of beneficial organic matter. Plus, its texture and drainage make it suitable for planting.


Silt is nutrient-rich, and its fine texture does a relatively good job of retaining moisture. It’s light-colored with a neutral pH.  


Sandy soil isn’t an ideal choice on its own for gardening, as it’s too lightweight and low in nutrients. However, its texture makes it perfect for mixing into heavier, denser soils.


Peat soil only occurs naturally in a few places. It’s full of lightweight organic matter and provides superior drainage.

What is Topsoil Made Of?

Now, you know that topsoil can come in all different forms. But what is topsoil made of? The ideal topsoil composition would be 25% air, 25% liquid, <50% solid particles, and <5% organic material. Of course, these percentages vary by region. However, the type and amount of organic matter present is the key to having rich, fertile topsoil.

Water and Air

The best types of gardening topsoil contain small capillary pores to hold water and large capillary pores to hold air, ensuring easy access for the plant. The number, size, and type of capillary pores differ in each topsoil. For example, sandy topsoils have pores that improve water retention, but they have too much air, which causes excessive drainage. Clay topsoils are denser and have numerous pores that enable superior water retention. But, those pores also limit airflow, and their small size restricts water access.


Did you know most soils consist of 95% mineral particles, which originate from bedrock and other rock deposits? The size of mineral particles also directly affects soil type. For example, clay soil has the smallest size of particles. The microorganisms in topsoil continuously break down these particles, releasing acid and minerals that provide nutrients vital for plant growth.

Organic Matter

The term “organic matter” can refer to a wide variety of living organisms and decomposing residues from plants and animals. All those tiny microorganisms in the soil work tirelessly to break down the organic matter. This process releases essential elements that plants use for food, like sulfur, nitrogen, and phosphorous.

Topsoil vs. Other Kinds of Soil and Dirt: What’s the Difference?

You’ve probably heard people use terms like “topsoil” and “dirt” interchangeably, but all types of dirt have fundamental differences and purposes.

Topsoil vs. Gardening Soil

Gardening soil is technically topsoil. However, it undergoes a screening process and then receives an infusion of compost. It’s too heavy for planters but is ideal for lawns or garden beds.

Topsoil vs. Potting Soil

The name “potting soil” is a misnomer — it doesn’t actually contain any soil! Instead, it’s a super lightweight mix of perlite and peat moss. Some types also contain slow-release fertilizer or wetting agents.

Topsoil vs. Dirt

Topsoil is for growing plants, whereas dirt is not. Dirt’s specific purposes include filling in holes, landscaping, and grading. 

topsoil made of

Having Topsoil Trouble? Let GrowBox Solve All Your Gardening Woes!

Not everyone is born with a green thumb. In fact, growing a garden full of happy, healthy plants is no easy task. You have to know which topsoil to use, when to fertilize, how to follow a proper watering schedule, and so much more. If you’d love to have a garden full of juicy red tomatoes and other veggies, but you’re struggling to get started, our GrowBox planter is the solution to all your gardening problems.

We designed GrowBox to deliver constant nutrition, oxygen, and water to your plants for maximum growth and productivity. Our Nutrient Patch™ ensures proper plant spacing and automatic fertilization, providing essential nutrients and stopping weeds right in their tracks. It couldn’t be easier: fill up your GrowBox with potting mix, lay the Nutrient Patch™ on top, follow the numbers to plant your seeds, then water it every couple of days and watch your plants flourish and thrive!

So, if you used to wonder, “What is topsoil made of?” hopefully, we’ve now answered that question. Topsoil is the uppermost layer of soil and consists of water and air, organic matter, and minerals. For answers to all your gardening questions – like signs of a healthy soil, how to set up your GrowBox, and more – browse our blog and additional resources. Call A Garden Patch now at (800) 519-1555 to order your GrowBox over the phone or head to our website to order online.

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