Exploring the potential of vermicompost in horticulture: a meta-analysis of seedling growth and sustainable cultivation

• Vermicompost at low concentrations promotes seed germination and seedling growth, while higher concentrations inhibit germination. • The yield increase effects of vermicompost were as follows: radish (38.92 %) > chili (38.26 %) > Chinese cabbage (28.11 %) > tomato (18.36 %) > cucumber (15.3 %). • Vermicompost reduces nitrate content in vegetables while also enhancing nutrients such as vitamin C and soluble sugar. • Vermicompost significantly enhances soil enzyme activity and nutrient content, including organic matter and total nitrogen, without disrupting the soil pH balance. Vermicompost is widely used in vegetable nurseries and field cultivation; however, quantitative assessments of its effects on yield, quality and soil in vegetable cultivation are lacking. Therefore, here, a meta-analysis was performed to comprehensively evaluate the effects of vermicompost on a series of morphological traits related to vegetable emergence and the effects on seedling cultivation in vegetable nurseries, as well as on vegetable yield, vegetable quality, and soil properties during field cultivation. We observed that (1) the vermicompost application rate had a significant concentration-dependent effect on vegetable growth and development. The best results were obtained under 0–20% vermicompost application, with a 23.69% increase in germination, whereas high-concentration treatment at 80–100% resulted in a 4.9% reduction in seedling emergence. Vermicompost had pronounced promotional effects on the stem diameter, leaf number, and height of seedlings. However, its impact on leaf SPAD was minimal and even exhibited significant negative correlations under specific treatment conditions. (2) Different pH values and application amounts of vermicompost can significantly increase vegetable yield. The yield increase effects on five kinds of vegetables were as follows: radish (38.92%) > pepper (38.26%) > cabbage (28.11%) > tomato (18.36%) > cucumber (15.3%). (3) Vermicompost can effectively reduce the nitrate content of vegetables while significantly increasing the vitamin C, soluble sugar and soluble solid contents to optimize vegetable quality. (4) Vermicompost, which is rich in microbial and enzymatic activities, significantly promotes organic matter decomposition and nitrogen conversion, while the carbonate and organic acid in the manure form a buffer system to maintain soil pH stability, thus increasing enzyme activity (urease, 55.27%; sucrase, 45.26%; peroxidase, 55.44%) and nutrient enrichment (38.54% of organic matter; total nitrogen, 30.63%) without significantly altering the acid‒base balance. In conclusion, this study clearly showed that vermicompost significantly improves vegetable seedling morphology and vegetable yield and quality and has great potential for soil improvement. These findings provide an important theoretical basis and practical guidance for the popularization and application of vermicompost in modern sustainable agriculture.