Litterick, A., Earthcare Technical Ltd.(free)
This project determined, through a combination of visual/tactile assessments of potential constituents, laboratory tests, manufacture of test topsoil blends and glasshouse pot and plot trials, that it was possible to manufacture a range of multi-purpose, calcareous and acidic BS 3882-compliant topsoils from wholly recycled materials including green and food-derived compost. It did not prove possible to manufacture low fertility topsoils using the materials available during the project. Manufacture of topsoils from recycled materials was shown to have advantages in terms of both financial and environmental sustainability in comparison with use of natural topsoils in some situations.
Keywords: Topsoil, green compost, food-derived compost, BS 3882:2007
Introduction and project aims
Both natural and manufactured topsoils of suitable quality can now be considered compliant with the revised British Standard for topsoil (BS 3882:2007). New business opportunities therefore exist for topsoil manufacturers, waste managers and landscapers/developers to create and use topsoils based partly or wholly on recycled waste materials, thus reducing the volumes of organic and inert wastes being sent to landfill and improving resource efficiency. There has been limited work published which shows the potential for using green and food-derived composts to manufacture BS 3882-compliant topsoils.
The main aim of this project was to determine, through a combination of visual/tactile assessments of potential constituents, laboratory tests and manufacture of test topsoil blends whether it was possible to manufacture a range of BS 3882-compliant topsoils from wholly recycled materials including green and food-derived compost. An additional aim was to attempt to manufacture at least two topsoils which were compliant with each of the four BS 3882:2007 categories (i.e. multipurpose, calcareous, acidic and low fertility). Pot and plot trials using BS3882-compliant blends were then conducted using eleven of the best topsoil blends (compared with a single natural topsoil), with the aim of determining the growth and performance of an amenity grass/wild flower seed mixture. A financial and environmental audit of the topsoil manufacturing process was completed, based on cost and revenue estimates obtained from the project partner company, Realm Construction Ltd. The aim of this audit was to determine whether there were financial and/or environmental benefits associated with manufacturing topsoils rather than using natural topsoils. This paper is a summary of work conducted in WRAP project OBF009-020 (Topsoil Manufacture using quality composts, WRAP, unpublished). The full report will be available on the WRAP website shortly.