51 / 2023-05-09 14:56:27

Aerobic co-composting of mature compost with cattle manure: Organic matter conversion and microbial community characterization

Cattle manure; Composting; Lignocellulose; Humification; Microbial communities

With the expanding demand for meat, eggs, and dairy products, the livestock industry is gradually changing from a traditional small-scale, small-group dispersed feeding model to an intensive, industrialized farming model. However, the expansive development of the livestock industry fails to support the corresponding infrastructure or provide sufficient management experience. The extensive emissions of livestock manure pose a serious threat to the sustainable development of the ecological environment. Livestock manure is enriched with many nutrients, such as organic matter, nitrogen, phosphorus, potassium, crude protein and crude fiber. If the nutrients in livestock manure can be recirculated, then this process would be of great importance for promoting the sustainable development of livestock farming. Aerobic composting is one of the main ways to make livestock manure stabilized and harmless, thus becoming resource. Aerobic composting uses aerobic fermentation of microorganisms to achieve mineralization decomposition and humification of livestock manure. This type of composting also produces fertilizer products with added value while rendering it harmless. In this study, mature compost was added to cattle manure to investigate the microbial enhancement mechanism of compost humification. The results indicated that the addition of mature compost expedited the aerobic compost humification process. At the end of composting, the lignocellulose degradation rate was 35% and the germination index was 98%. Macrogenomic analysis showed that the addition of decomposed compost enhanced the activity of carbohydrate-active enzymes, changed the microbial community succession pattern, and increased the abundance of thermophilic microorganisms (Thermobifida) and organic matter degrading functional microorganisms (Natronosporangium, Micromonospora and Actinomadura). The addition of mature compost also promoted microbial community interactions and potential functions. More mutually beneficial symbiotic interactions and stronger metabolism of microbial communities in the group with the addition of mature compost than in the control group, especially carbohydrate metabolism and amino acid metabolism, were driving forces for cellulose degradation and humus formation. These findings provide a more cost-effective strategy for improving the efficiency and quality of aerobic composting of cattle manure.