This report details the research into a standardised stability test method that is capable of being used to measure compost stability consistently in laboratory conditions and can be used as a standard test throughout the UK and potentially Europe.


Compost stability is a key characteristic which determines the value and marketability of composted materials. A previous WRAP project (STA0005) assessed a range of potential options for measuring compost stability in the laboratory. For the purposes of this project, stability was defined as the aerobic biological activity and the project concentrated on developing a method to assess this.

Numerous options were assessed, mostly involving respirometry, using measurements of oxygen demand, carbon dioxide emission or heat production. The project developed a “Standardised Method for the Determination of Compost Stability by Measurement of Evolved Carbon Dioxide” under controlled conditions.

The previous WRAP project, initiating this work (STA0005) recommended that more work was needed to optimise and validate the method. This project finalises that standardised method by optimising the conditions under which the test is conducted, namely moisture adjustment, pre-incubation conditioning, incubation temperature and nutrient supplementation, to quantify its precision, and develop a matrix of limit levels for each relevant end-use.

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  • WRAP-DevLabTestCompostStability.pdf

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