Evaluation of compost quality and the environmental effects of semipermeable membrane composting with poultry manure using sawdust or mushroom residue as the bulking agent*

Herein, the effects of different bulking agents (sawdust and mushroom residue), on compost quality and the environmental benefits of semipermeable film composting with poultry manure were investigated. The results show that composting with sawdust as the bulking agent resulted in greater efficiency and more cost benefits than composting with mushroom residue, and the cost of sawdust for treating an equal volume of manure was only 1/6 of that of mushroom residue. Additionally, lignin degradation and potential carbon emission reduction in the sawdust group were better than those in the mushroom residue group, and the lignin degradation efficiency of the bottom sample in the sawdust group was 48.57 %. Coupling between lignin degradation and potential carbon emission reduction was also closer in sawdust piles than in mushroom residue piles, and sawdust is more environmentally friendly. The abundance of key functional genes was higher at the bottom of each pile relative to the top and middle. Limnochordaceae, Lactobacillus and Enterococcus were the core microorganisms involved in coupling between lignin degradation and potential carbon emission reduction, and the coupled relationship was influenced by electric conductivity, ammonia nitrogen and total nitrogen in the compost piles. This study provides important data for supporting bulking agent selection in semipermeable film composting and for improving the composting process. The results have high value for compost production and process application.