Effects of Exogenous Microbial Agents on Soil Nutrient and Microbial Community Composition in Greenhouse-Derived Vegetable Straw Composts

Vegetable waste causes resource waste and environmental pollution, giving rise to the spread of harmful organisms and causing disease in normal vegetable cultivation. Random distribution of vegetable waste can increase the risk of non-point agricultural pollution and explore the feasibility of its resource utilization. This study was designed to evaluate the effects of different doses of exogenous microbial agents on soil microbial communities after in situ composting of cucumber straw on plots with biodegradable mulch films. The cucumber straw and chicken manure were used as the base materials, and the next generation sequencing was used to analyze changes in the microbiome following composting. The results demonstrate that the addition of exogenous microbial agents had prolonged the high-temperature duration, reduced the total organic carbon (TOC) content, and accelerated the decline in the C/N ratio, ensuring compost maturity and effectively shortening the composting time. The predominant bacterial phyla of the four treatment groups were Proteobacteria and Firmicutes; while among fungal phyla, these treatments decreased the relative abundance of Ascomycota. The treatment of 300 t/ha microbial agents significantly increased the richness and diversity of both the bacterial and fungal communities. Redundancy analysis suggested that soil total nitrogen (TN) content had a significant effect on the bacterial community, while TN content, pH, and temperature influenced the fungal community in these samples. Collectively, the treatment of 300 t/ha exogenous microbial agents improved the quality of composting and promoted microbiome diversity.