Topsoil: It’s just dirt, isn’t it?

We catch up with MCM’s Darrel Burgess to discover why there’s a lot more to topsoil than meets the eye.

There was a time when topsoil was simply dug out of one site and delivered to another, with very little thought about what was actually in it. These days, things are rather different. “People tend to think that topsoil is just dirt,” says Darrel Burgess, MCM’s Sales and Soil Development Director. “But there’s a lot more science involved than you might imagine.”

The importance of soil testing

Today, soil recovered from construction sites will often undergo testing for contaminants, including substances such as polycyclic aromatic hydrocarbons (PAHs), before decisions are made about how it can be handled, treated or reused.

“Quite often, we’ll get a call from a contractor who’s about to start excavating a site. They want to know what they can do with all the soil they’re digging out. We’ll arrange testing to establish what we’re dealing with and then see whether we can find a suitable use for it.”

Not all topsoil is created equal

And that’s where things start to get interesting.

Some projects require low-nutrient soils for wildflower meadows, while others need lightweight growing media for roof gardens. Depending on its properties, recovered soil can be taken to one of MCM’s batching facilities and blended with other materials to create something entirely different.

“One of my favourite examples was the Queen Elizabeth II Garden in Regent’s Park,” recalls Darrel. “We supplied concrete from Heathrow Airport, selected from three tested samples, that was used as one of the base ingredients for the low-nutrient growing medium for the wildflower meadows.”

It’s a rather wonderful thought that material recovered from one of the world’s busiest airports could end up helping wildflowers flourish in the middle of London. By incorporating recycled materials, the project also supported its wider sustainability objectives.