Soil Accelerates the Humification Involved in Co-Composting of Wheat Straw and Cattle Manure by Promoting Humus Formation

In aerobic organic waste composting, lignocellulose degrades and is converted slowly, reducing composting effectiveness and humus production. Soils have a porous nature, buffering capacity and a wide range of nutrients that are beneficial for the microbial contribution to composting efficiency and humus formation. This study aimed to determine how soil affects lignocellulose decomposition, humification and microbial metabolism during composting. It was found that for the control and treatments with added fluvo aquic soil (FAS), dark loessial soil (DLS) and yellow brown soil (YBS), the relative hemicellulose content decreased by 7.4, 11.8, 13.3 and 11.8%, relative cellulose content decreased by 1.5, 7.7, 6.2 and 6.8%, and humic acid content increased by 10.1, 36.4, 35.5, and 28.2% respectively, indicating that the addition of soil elevated humus content of the compost. FAS, DLS and YBS addition enriched the specific hydrolytic bacteria Corynebacterium, and its relative abundance increased by 187, 120 and 22%, respectively, which promoted organic matter degradation. In addition, in carbohydrate metabolism, glycolysis increased by up to 11%, and starch and sucrose metabolism increased by up to 12% forming substances such as reducing sugars and polyphenols, which promoted compost humification through the polyphenol and Maillard humification pathways. This study demonstrates a novel option and mechanism for rapid degradation and humification of organic materials in composting.