Soil Basics: What Is Topsoil Composed Of?

To grow a healthy garden or a beautiful landscape, you need a hearty layer of topsoil that will fit your growing needs (and work with the climate you live in). 

Topsoil is exactly that: it’s the soil sits on the outermost layer of the Earth. It’s easy to access and dig through for gardeners and anyone making shallow impressions in the ground. It’s also the layer of Earth where seeds germinate and plants begin to grow. 

Different types of topsoil have different benefits, but in general, all topsoil is made from the same few ingredients. Let’s go through the basics of what we can find in topsoil:

Clay, Sand, and Silt

You’ll find these particles in dirt and in soil. Different combinations of each will determine the density and abilities of your topsoil. The different amounts of clay, sand and silt you find in your topsoil will typically depend on the source of your topsoil and your location. Each ingredient will have different benefits for different types of growing. 

So what’s the difference? 

Sand has particles that are big in size, making it easy for air to circulate. Sand is found in more coastal areas, and is great for growing root vegetables. These types of vegetables require more water drainage and less water retention. 

Clay, on the other hand, can hold more water, and is better suited for growing in dry areas. Clay topsoil is especially dense, as the particles are smaller and easy to pack together.

Silt is a sedimentary particle that is sized somewhere between sand and clay. Soil that is compromised of more silt will provide a nice balance between water drainage and air circulation. It is extremely fertile soil. It’s typically found in areas near floodplains. 

Different types of topsoil will contain different proportions of all of these particles, but “just right”topsoil aims to be 60% sand, 15% clay, and 25% silt.

Organic Matter

Topsoil is unique because it has the highest concentration of organic matter compared to other types of soil or dirt. Organic matter is the leftover material from plants: roots, stems, leaves, etc. 

When a plant dies, the organic matter is left to nourish the topsoil and any new plants that will grow from the topsoil. Decomposed organic matter is also commonly called “humus.”

Nutrients

As organic matter decomposes, it breaks down and leaves the topsoil with nutrients at the most basic level. These nutrients include, but are not limited to:

• Carbon
• Nitrogen
• Calcium
• Sulfur
• Potassium
• Phosphorous

All of these nutrients have their own benefits, and are required for healthy plant growth. 

The Importance of Bugs

The presence of worms, beetles, and other small insects are also common and healthy for topsoil functions. Worms in particular are great for helping plants and organic matter decompose faster. 

Getting nutrient-rich topsoil is a key element to growing a healthy and lively garden. Additionally, there are other benefits that topsoil can provide. To learn more about how topsoil can help you – and which is best for your needs – contact DirtMatch today.