This study investigated the effects of liquid bio-fertilizer (LBF) on the growth, antioxidant activity, soil properties, and soil microbial composition of Chinese cabbage (Brassica rapa L. ssp. pekinensis). The LBF application significantly enhanced vegetative growth by increasing the leaf length, leaf width, fresh weight, and dry weight. Additionally, antioxidant activity increased with rises in total phenolic and flavonoid contents. However, the per-unit antioxidant concentrations decreased, likely due to rapid biomass accumulation. Soil analysis showed improvements in pH, organic matter, and available phosphorus. Microbial analysis revealed that Acidobacteria enrichment was associated with enhanced nutrient cycling despite reduced overall microbial diversity. Transcriptomic analysis identified 445 differentially expressed genes with upregulation in the metabolism and photosynthesis-related pathways, suggesting improved nutrient assimilation and energy production. These findings demonstrate that LBF enhances plant growth and soil fertility while influencing microbial dynamics and gene expression.

The combined compost tea and biochar treatment (BC) showed more distinct responses than compost tea alone, particularly in selected growth-related traits. Plant height, leaf width, and SPAD value increased under the BC treatment at specific growth stages, whereas final fresh weight did not differ significantly among treatments. Antioxidant-related traits also showed no significant differences among treatments. Compared with the control treatment and, where applicable, the compost tea alone treatment, the BC treatment was associated with selective changes in plant ion composition, including increased K⁺ concentration and decreased Ca²⁺, Cl⁻, and NO₃⁻ concentrations in basil tissue extracts. In soil, the BC treatment was associated with increased pH, organic matter, NO₃⁻-N, and exchangeable Mg, and decreased NH₄⁺-N and exchangeable Na. Soil bacterial community analysis revealed treatment-related shifts in community structure, and these changes were associated with soil chemical properties, including pH, organic matter, inorganic nitrogen forms, and exchangeable cations. Genus-level analysis within Chloroflexi further indicated that the BC treatment was associated with changes in bacterial taxonomic composition. Overall, the combined compost tea and biochar treatment selectively affected basil growth-related traits, plant ion composition, soil nutrient status, and bacterial community structure. However, because a biochar-only treatment was not included, these responses should be interpreted as effects associated with the combined compost tea and biochar treatment rather than as effects attributable to biochar alone.

This study presents an observational analysis of the chemical and microbial dynamics of cattle manure compost during maturation in a system inoculated with Lactobacillus acidophilus. Composting samples were collected at D15 and D60 to assess changes in key nutrient parameters and microbial community shifts from the early stage to the composting phase. At D60 in this inoculated composting system, ammonium nitrogen (NH₄⁺-N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), and total nitrogen (T-N) levels were higher than at D15, with NH₄⁺-N measuring 813.01 and 1714.24 mg/kg at D15 and D60, respectively (p < 0.001). Microbial analysis based on 16S rRNA gene sequencing showed that alpha diversity was slightly lower at D60 than at D15, although this difference was not statistically significant; in contrast, the community composition shifted toward a higher relative abundance of Firmicutes and lower relative abundances of Bacteroidetes and Proteobacteria. Mantel correlation analyses indicated strong associations between specific bacterial phyla and manure chemical properties, particularly between Firmicutes and levels of NH₄⁺-N, chloride, and sodium. PICRUSt2-based functional prediction further suggested that mature compost samples had a higher predicted representation of genes associated with nitrogen- and energy-related pathways, including arginine and polyamine biosynthesis and butanoate fermentation. This observational study outlines how nutrient profiles, microbial communities, and PICRUSt2-predicted functional potentials change over time in a composting system amended with L. acidophilus. By documenting these characteristic patterns, our results provide a useful reference for focusing future research on specific nutrient–microbe–function linkages in lactic acid bacteria-amended composting systems, and for interpreting compost maturation in such systems within the context of sustainable agricultural practice.