Property changes in the Castanea mollissima Blume shell during composting and an evaluation of the compost maturity

The recycling and utilization of the Castanea mollissima Blume shell can ensure the sustainable development of its processing industry. Composting the C. mollissima shell yields a safe compost product with a high maturity level. In this study, the changes in the temperature, carbon to nitrogen ratio, ammonium-nitrogen levels, nitrate-nitrogen levels, and the seed germination index of composting C. mollissima shells were monitored during its co-composting process with sheep and chicken manure, and a compost maturity index system was established. The results suggested that livestock and poultry manure could accelerate the composting process of C. mollissima shells and prolong the thermophilic phase during the composting. Both the carbon to nitrogen ratio and the ammonium-nitrogen levels in the compost decreased with the prolongation of the composting time, while the nitrate-nitrogen levels and the seed germination index increased during the compositing process. A Pearson correlation analysis indicated that carbon-nitrogen ratio, nitrate-nitrogen levels, and the seed germination index could be used to evaluate the compost maturity of C. mollissima shells.