Effect of spent mushroom substrate as a bulking agent on gaseous emissions and compost quality during pig manure composting

Abstract

The aim of this study was to investigate the gaseous emissions (CH₄, N₂O, and NH₃) and compost quality during the pig manure composting by adding spent mushroom substrate (SMS) as a bulking agent. The control treatment was also studied using corn stalk (CS) as a bulking agent. The experiment was conducted in a pilot scale composting reactor under aerobic condition with the initial C/N ratio of 20. Results showed that bulking agents significantly affected gaseous emissions and compost quality. Using SMS as a bulking agent improved composting efficiency by shortening the time for maturity. SMS increased germination index and humic acid of the final compost (by 13.44 and 41.94%, respectively) compared with CS. Furthermore, composting with SMS as a bulking agent could reduce nitrogen loss, NH₃, and N₂O emissions (by 13.57, 35.56, and 46.48%, respectively) compared with the control. SMS slightly increased CH₄ emission about 1.1 times of the CS. However, a 33.95% decrease in the global warming potential of CH₄ and N₂O was obtained by adding SMS treatment. These results indicate that SMS is a favorable bulking agent for reducing gaseous emissions and increasing compost quality.