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The central aim is to assess the impact of koohbanan organic biochar on microbial activity and enzyme activities during in-vessel co-composting of animal manures.

March 10, 2026Open Access

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Assessing Compost Stability: Microbial Activity and Maturity Indices in In-Vessel Co-Composting of Animal Manure

MMMitra MohammadiKermanshah University of Medical Sciences AAAli AlmasiKermanshah University of Medical Sciences

Key Points

The central aim is to assess the impact of koohbanan organic biochar on microbial activity and enzyme activities during in-vessel co-composting of animal manures.
Analyzed 12 treatments with three cow manure/poultry manure mixtures (50:50, 25:50, 75:25).
Applied varying levels of biochar (5%, 10%, 15%) to each treatment.
Measured enzymatic activities (dehydrogenase, alkaline phosphatase, urease) over time.
Optimal enzyme activities occurred at 75% poultry manure with 15% biochar.
Enzyme activity increased significantly with biochar amendments, particularly dehydrogenase and alkaline phosphatase.
Up to a 210% increase in alkaline phosphatase activity was observed at 10% biochar.

Abstract

• Effect of innovative biochar on enzyme activity in Invessel composting was studied. • Dehydrogenase, alkaline phosphatase, and urease were the enzymes affecting compost. • Biochar dosage: 10 % and CM/PM: 1:3 was optimal for the process advancement. Effective animal waste management is essential to prevent environmental pollution, protect public health, and promote sustainable agricultural practices. This study evaluated the co-composting of animal manures (AMs) in an in-vessel system, focusing on the impact of koohbanan organic biochar (KOB) on physical–chemical properties and enzymatic activities. 12 treatments were analyzed across three groups (50:50, 25:50 and 75:25 mixture of cow manure/ poultry manure), with KOB amendments (5 %, 10 %, and 15 %). Enzymatic activities, including dehydrogenase and urease, increased and decreased, respectively, during the bio-oxidation process. Adding KOB significantly enhanced enzyme activities, improved physical properties and accelerated organic matter mineralization. The higher proportion of cow manure at lower KOB showed limited performance, as enzyme activity (Dehydrogenase: 0.21 mg TPF/gDW.h; alkaline phosphatase: 0.19 mg Phenol/gDW.h; Ureas: 18.65 µg NH4/g.d) was lower at KOB, 5%. The 75% poultry manure groups exhibited high enzyme activities at 15% KOB (Dehydrogenase: 0.23 mg TPF/gDW.h; alkaline phosphatase: 0.27 mg Phenol/gDW.h; Ureas: 16.14 µg NH4/g.d). The highest APH activity was observed in treatments with up to 10% KOB, with T11 showing about a 210% increase compared to the control. No significant differences were observed in URS activity among days 40- 60. These results indicate that KOB amendments and poultry manure play a very important role in increasing microbial activity and consequently enzyme activity, improving physical properties, and efficient decomposition of animal manures. The findings emphasize the co-composting of animal waste as a sustainable management strategy.

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Assessing Compost Stability: Microbial Activity and Maturity Indices in In-Vessel Co-Composting of Animal Manure

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