Objectives The aim was to study the effects of adding thermophilic agents on the fermentation efficiency, lignocellulose degradation and compost quality during the composting of cow manure.
Methods The fermentation was conducted using cow manure and corn stalks as raw materials. Testing thermophilic agents (GLL) were mainly composed of Thermoactinomyces vulgaris, Ureibacillus terrenus and Geobacillus thermodenitrificans, and two commercially available agents A, B for organic fertilizer fermentation set as controls while setting a blank control (CK) without inoculating agent, and the fermentation test is 30 days. The samples were obtained on 0, 3, 7, 12, 16, 23, 30 days in composting, dry samples were used for determination of lignocellulose content in composting, and fresh samples were used to determine moisture content, pH, EC value, seed germination index (GI), and bacterial community structures.
Results The GLL treatment quickly warmed up to the hyperthermophilic period (85.8℃) within the composting for 2 days, and this period lasted for 5 days; the CK, A, B treatments entered the thermophilic period (56.3℃, 59.2℃, 57.6℃) of composting on the composting for 3 days, and this period respectively lasted for 10, 11, 13 days. The inoculation of GLL significantly reduced the moisture content of the compost to 34.3% at the end of the composting, and the CK, A, B treatments dropped to 45.4%, 43.8%, 44.6%, which did not meet moisture standard of the product. The content of hemicellulose, cellulose and lignin in the GLL treatment decreased by 81.6%, 65.2% and 53.7% respectively compared to the initial value after composting, and the degradation capacity of lignocellulose significantly exceeded that of CK, A, and B treatments. During thermophilic even hyperthermophilic periods of composting, the relative abundance of Firmicutes in the bacteria increased to 46.6% in GLL treatment. The indicators of the compost i.e., the mass fraction of organic matter, total nutrients and mechanical impurities, pH and GI values, all met the requirements of NY/T 525—2021 after the hyperthermophilic fermentation by inoculating GLL agent.
Conclusions Inoculating thermophilic agents can significantly increase the temperature during the composting, extend the duration of the thermophilic period, achieve hyperthermophilic composting, reduce the moisture content, and improve the degradation effect of lignocellulose, and quickly obtain the compost that meets the requirements of NY/T 525—2021.
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