Module 4: Compost Quality

Once the composting process requirements have been met, it is necessary to evaluate the product to determine its suitability as a soil amendment or horticultural growing medium. A number of organizations have developed standards related to compost quality, and in this module, students learn more about these standards and the tests used to assess the suitability of compost for various end uses or markets for compost. In the Module 4 assignment, students use some of these tests to evaluate the maturity of their own compost, and determine the extent of decomposition which has occurred in their mix during composting.

Compost quality may be considered a bridge between compost production and compost use, and therefore contains essential elements of both. Compost quality embraces all of the traits which are important in the use of compost (e.g., stability, nutrient content, disease suppressive properties, and pathogen, weed seed, and other contaminant content), and yet these traits are largely determined by the choice of starting feedstocks and the way in which compost is produced. The on-line discussion forum provides students with an opportunity to exchange views and information on these topics, and thereby deepen their understanding of compost quality.