International Journal of Recycling of Organic Waste in Agriculture (IJROWA) Co-composting of coir pith and cow manure: initial C/N ratio vs physico-chemical changes Volume 1 (2012) Issue 1, December 2012 2024 02 01 Co-composting of coir pith and cow manure: initial C/N ratio vs physico-chemical changes EN Sudarut Tripetchkul Natural Resource Management and Sustainability program, School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi, Tha Kham, Bang Khun Thian, Bangkok, 10150 Thailand Kanokwan Pundee College of Multidisciplinary Sciences, King Mongkut’s University of Technology Thonburi, Tha Kham, Bang Khun Thian, Bangkok, 10150 Thailand Songpon Koonsrisuk Pilot Plant Development and Training Institute,King Mongkut's University of Technology Thonburi, Bangkok,Thailand Saengchai Akeprathumchai Biotechnology program, School of Bioresources and Technology, King Mongkut’s University of Tech-nology Thonburi, Tha Kham, Bang Khun Thian, Bangkok, 10150 Thailand Journal Article 2024 02 01 Background: As objective of this study was focused on efficacy of composting of a recalcitrant organic waste material, co-composting of coir pith with cow manure and rice bran was endeavored to evaluate influence of initial C/N ratios, i.e., 30, 25, and 20, on physico-chemical changes, e.g., temperature, pH, organic matter (OM) degradation, and total nitrogen (TN) losses. Results: Results showed that OM and TN losses were significantly affected by C/N ratio (p < 0.05), whereas C/N ratio played insignificant role on temperature and pH evolution within the pile (p > 0.05) during composting process. OM and TN losses were highest within the first 2 weeks of thermophilic phase. Through the composting process, pile with 25 C/N ratio showed the highest biodegradation rate constant of organic matter (k = 0.309 day−1 ) and the highest TN losses (41.9%), while pile with C/N ratio of 30 showed the lowest N loss (−7.3%). However, for all three compost piles, maturity, as indicated by the pile temperature converging to the ambient temperature, was attained within 1 month post-composting. Conclusion: Results suggested that simple pile turning yielded effective co-composting of coir pith under comparatively low C/N ratio. Considering the composting performance and the amount of coir pith to be utilized, the initial C/N ratio of 30 was considered suitable for coir pith composting.