Compost maturity - problems associated with testing

Merja Itävaara, Olli Venelampi, Minna Vikman, Anu Kapanen

    Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional


    Safe use of compost in plant cultivation requires the utilization of mature compost. The complex composition of the organic matter and the changes occurring during biodegradation make maturity assessment a difficult task. In the present study we give an overview of the test methods applied, and some scientific background for the immaturity and toxicity of the compost samples.

    The results of the acute toxicity test, Flash bioluminescent bacteria test Vibrio fisheri, correlated well with those of the plant growth assays. The immature composts studied were toxic in the Flash test and plant growth assays when processed for less than 3 months, but nontoxic after maturing during six months of composting.

    In the present study we showed that oxygen deficiency during composting processing resulted in the development of toxicity in the compost. It was also confirmed that oxygen is a requirement for good quality compost, insufficient aeration during processing resulting in poor quality and retarded growth of the plants.

    In order to evaluate the maturity of compost, stability and toxicity at least should be studied. Special attention should also be paid to the moisture content when testing stability with respirometric tests. This avoids the problem of false evaluation due to the lack of water needed for microbial respiration. Large-scale composting facilities very often run their composting processes with insufficient moisture content and aeration, resulting in reduced biodegradation and an increase in the length of time required to reach maturity. The moisture content of samples taken from such a composting facility should be balanced before testing for maturity.
    Original languageEnglish
    Title of host publicationMicrobiology of Composting
    EditorsHeribet Insam, Nuntavun Riddech, Susanne Klammer
    Place of PublicationBerlin - Heidelberg
    ISBN (Electronic)978-3-662-08724-4
    ISBN (Print)978-3-642-08705-9
    Publication statusPublished - 2002
    MoE publication typeD2 Article in professional manuals or guides or professional information systems or text book material


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