There are many different grades of topsoil, with classification defined by characteristics such as structure, fertility, contents and chemical composition.
Much of this is governed by the source of the product and its raw materials because, in some instances, topsoils have been found to contain unwanted elements. These elements can include Potentially Toxic Elements (PTEs) or high concentrations of certain chemical elements, both of which can result in total plant failure.
Therefore, selecting the right product, designed for the job in hand and from a trusted supplier, is essential to achieve the best outcome for your garden or landscaping scheme.
What is the topsoil going to be used for?
The starting point is to determine what the topsoil is to be used for as the specification will vary depending on the application. For example, is it going to be used for laying turf or lawn seeding, growing vegetables and fruit, constructing raised beds or general landscaping?
Once the application has been determined, it is important to obtain answers to the following questions before buying:
What is in the soil?
Where is it from?
What task is it designed for?
Does it meet British Standard BS 3882:2015 AND has it been classified as being suitable for residential home-grown use?
Is a copy available of the independent test analysis required to prove compliance to the British Standard, along with the required report of suitability?
Does the testing include analysis of PTEs (Potentially Toxic Elements)?
Are the supplier’s quality and environmental management systems certified to BS EN ISO 9001:2015 and BS EN ISO 14001:2015?
Your topsoil supplier should be able to answer all the above questions and provide evidence of test results and certification.
Watch our 'Topsoil you can trust' video for advice on which Rolawn topsoil is right for your needs.
Creating a topsoil specification
For larger projects, creating a topsoil specification will help to ensure the quality and suitability of any imported topsoil. It details what should and should not be in the topsoil. The topsoil specification therefore needs to include the technical elements that will ensure an effective growing medium is provided.
The most functional specifications are those that list which properties the topsoil should possess prior to turfing, planting or seeding.
These normally include:
Visual examination - soil structure, consistency, foreign matter, etc.
Particle size analysis (texture) and stone content
pH and salinity values
Major plant nutrients (N,P,K)
Organic matter content
Potential contaminants (e.g. heavy metals, hydrocarbons, cyanide, phenols)
The values set against each property will depend on the required performance of the topsoil. Do not be tempted to use the same specification for every landscape project. Usually some modification to a 'template specification' is required and it may be necessary to have more than one specification if a variety of different landscaped areas are to be created. The specification also needs to take site considerations into account, such as the local climate, drainage, aspect of the site and construction constraints.
Once you have issued a specification, stick to it and do not be persuaded to change it on price alone.
For further information on Rolawn topsoils click here or contact us.