Understanding Manufactured Topsoil

What is manufactured topsoil?

Before I started working in the landscape industry, I thought soil was just soil.  Yes, there are different types depending on where you live.  And yes, you can improve what’s there by adding compost, manure, sand or grit according to what needs changing.

One thing I was sure of – soil is a natural thing.  Made by Mother Nature by centuries of weathering bedrock and adding compost.  So what the dickens is manufactured soil?

Having listened to Andy Spetch from British Sugar Topsoil talking at Soilscon 2016 I learned that manufactured topsoil isn’t manufactured at all.  It’s blended.  It’s different soil types mixed together to produce a consistent product with specific and measurable qualities.

What types of topsoil are available to buy?

When you start researching topsoil – either as a gardener, and engineer or a landscape architect; you realise that there is a lot of choice out there.

As-dug topsoil – is exactly what it says it is; You will find that the price is relatively attractive but you can’t be 100% sure of what you’re getting.  You may end up buying a something with a high proportion rubble, roots, weeds and rubbish.  It might even be contaminated. Probably best to avoid this unless you can inspect it thoroughly before you buy.

Screened topsoil has been passed through a big sieve to take out most of the debris.  A 20mm screened soil will only contain stones that are less than 2cm at their widest point.  It’s usually a nice texture for gardening.  However, unless you ask, you can’t always be sure if it will be sandy, silty, chalky or clay, acid or alkaline, nutrient rich or depleted. 

Blended (or manufactured) topsoil will have been tested thoroughly as part of the manufacturing process.  You can be confident that it contains no contaminants.  The supplier will be able to give you a breakdown of what nutrients are in the soil and what the handling properties are like.   

Why choose manufactured topsoil

With manufactured topsoil, you can select a grade that exactly meets your requirements.  Maybe you’re growing vegetables and need a slightly alkaline soil to deter soil borne diseases.  Perhaps you need acidity for plants like blueberries or camellias.  Maybe you want to grow wild flowers and need low nutrient soil

The best thing about manufactured topsoil is that if you have yours delivered in batches, each batch will be the same. 

Buying soil for general landscaping

Manufactured topsoil does have a price premium - which is perfectly understandable.  If you are gardening on a budget, buying screened soil from a reputable supplier might offer better value for money.

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