Effects of biochar size and type on gaseous emissions during pig manure/wheat straw aerobic composting: Insights into multivariate-microscale characterization and microbial mechanism.

•Granular-biochar improved pore volume and was benefit to methanotrophs activities.•Higher aromatic compounds on surface of bamboo biochar and NO3− formed π–π EDA.•Rice straw biochar is rich in reactive functional groups to adsorb NH4+.•Powder bamboo biochar was most suitable for controlling GHG and ammonia emissions.