There’s a big difference between topsoil that is formed naturally, and commercial topsoil that can be purchased from the gardening or home/outdoors shop.
In this guide we outline the differences between the two, and summarise how commercial topsoil is made.
How Natural Topsoil Is Made/Formed
Natural topsoil is formed from natural processes involving the breakdown of organic matter, and take a very long time to form on its own:
- … it takes time for topsoil to develop from the break down of organic matter (500 to 1000 years for 1-2 cms in some places).
How Is Commercial Topsoil Made?
Commercial topsoil can be purchased from the garden or home/outdoors shop, and is widely available to individuals. It can even be used on the industrial scale.
There’s many different types and quality of topsoil available.
For example, there might be a difference between an economy, and a premium topsoil mix. There might also be a difference in topsoils intended for landscaping vs gardening vs farming applications.
Different topsoils might also contain different mixes of soil types – such as sand, silt and clay. They might also contain different balances of macro nutrients and micro nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur are some of the most important macro nutrients).
Some soil is mined from one site with controlled or specific conditions, where as others might have soil sourced from several different sites with varying conditions.
Depending on the brand and product of topsoil, it can be made in different ways.
Despite the above variables and factors that make each commercial topsoil product different, they generally follow the same process in being made:
- Soil Is Sourced – different types of soil are sourced from one, or several soil sites. Different sites might have different conditions for the soil
- Clearing & Grubbing – soils are cleared of vegetation, and roots below the surface are removed
- Grading – the soil is pushed into manageable piles
- Pre Mixing Of Other Soils – the right quantities of sand, silt and clay can be mixed together to get the right topsoil texture. Adding more sand can help the soil drain better
- Pre Mixing Of Organic Matter – organic matter such as compost is mixed with soil. Organic matter is used to add nutrients to the soil mix.
- Screening – the soil is put into a topsoil screening plant which screens out materials bigger than a certain size – for example, stones, rocks, pieces of wood and plastic, metal or other types of manufactured waste. (note, not all topsoils are screened)
- Tumbling – the same plant tumbles the soil. This helps the soil become more uniform and gives it a better consistency
- Bagging & Delivery – the soil is now ready to be bagged and delivered to a shop, or straight to the customer
Topsoil should meet quality standards in your country.
Companies should also list on their website or packaging how they source and make their topsoil, and what it’s best for (different topsoil blends and products might be suitable for different applications).
So, research the topsoil you need, and also what you are buying, before you buy it.