Variation of microbial necromass carbon and its potential relationship with humification during composting of chicken manure with and without biochar addition

• DOI: 10.1016/j.biortech.2024.131258
• Publication Date: 2024-08-10T15:43:31Z
• Authors: Penghui Jia; Yimei Huang; Haixin Zhang; Qian Huang; Jinmei Chen; Lijing Feng; Ying Tuo; Longyu Yuan; Jinyi Xie
• Keywords: Humus; Chicken manure; Carbon fibers

Microbial necromass carbon (MNC) is an important stable organic C component. However, the variation of MNC and its potential relationship with humus components in composting remains uncertain. During a 45-day chicken manure composting study with and without biochar, MNC ranged from 24.9 to 77.9 g/kg and increased significantly by 80.9 % to 133 %. MNC constituted 5.77 % to 21.3 % of total organic C, with bacterial/fungal necromass C ratio ranging from 0.82 to 1.78. The MNC/humus C ratio ranged from 0.15 to 0.55, and humic acid C showed significant positive associations with bacterial necromass C (R2 = 0.63) and fungal necromass C (R2 = 0.43). Biochar addition reduced electrical conductivity and moisture content, increased pH, and induced microbial phosphorus limitation, thereby enhancing MNC content by 29.2 % and promoting humification. Our study is the first to elucidate the relationship between microbial necromass and humus substances, providing fundamental data for advancing the microbial carbon pump theory in composting.