Toward a Compost Pharmacopoeia—A Conceptual Framework for Standardisation and Classification of Compost Quality

Abstract

Compost quality assessment remains challenging due to substantial variation in standards, analytical methods, and reporting practices across jurisdictions and end-use applications. Differences in testing protocols and quality criteria limit data comparability among studies and compost products, while the absence of a common classification architecture hinders consistent interpretation of compost quality. This study proposes the Compost Pharmacopoeia Framework (CPF), a conceptual framework inspired by the organisational structure of pharmacopoeial systems. Existing standards, including AS 4454:2012, PAS 100:2018, and Regulation (EU) 2019/1009, were critically analysed to identify inconsistencies in physical, chemical, and biological quality assessment. Based on this analysis, the CPF integrates hierarchical classification, analytical methods, application-specific quality criteria, and reference materials within a unified framework for compost characterisation and reporting. The framework further introduces method equivalence concepts to facilitate comparison across non-equivalent analytical approaches. A representative experimental system is used to illustrate how compost quality information can be organised and interpreted within the proposed structure. In the representative nitrogen-regulated green-waste composting case, total nitrogen loss remained below 20%, while treatments were differentiated according to pH stability, nitrogen conservation, and germination performance, illustrating how CPF-organised data can support specific function interpretation. The CPF provides a foundation for improved data comparability, knowledge integration, and application-oriented compost classification, supporting more consistent communication among researchers, regulators, producers, and end-users.