The physical properties of compost

The trend toward more efficient methods of compost production and handling requires a complete understanding of the process, the materials involved, and the physical parameters of the materials such as moisture content, bulk density, and various mechanical properties. These properties influence the process and product in various ways from aeration effectiveness to compost-soil interactions. This paper reviews the influence of the physical properties of composting materials on the production and utilisation of compost. Methods for measuring moisture content, bulk density, particle size distribution, airflow resistance and the thermal and optical properties of compost are summarised. In addition to techniques for determining theses properties, typical values for particle density, porosity, and mechanical and electrical properties of composting materials are presented. Empirical formulas also are included for bulk density, particle density, free air space, and specific heat capacity, as cited in the reviewed literature. In the majority of cases, there is a lack of a specific standard for describing and measuring compost physical properties. In order to achieve uniformity, in reporting and comparability of data from various sources, acceptable standard. methods of measuring compost properties need to be adopted.