What is the Compost PAS 100 Standard?

Large-scale compost manufacturing in the UK makes compost that conforms to the PAS100 compost standard.

PAS100 leans towards ensuring the composting process has reached a point where the compost is mature and stable. The samples are tested for carbon to nitrogen ratio which is used to ensure it is ‘mature’ and ‘stable'. Available NKP nutrient levels, pathogens and heavy metal potentially toxic elements (PTEs) are also analysed in the laboratory.  

Finished compost should be both stable (resistant to decomposition) and mature (ready for a particular end-use).  

There are a few other Kitemark type schemes (eg Apex), but PAS100 is the main one.