Effect of Biochar and Bacillus Subtilis Xf-1 on Yield and Rhizosphere Soil Properties of Chinese Cabbage

It has become a common phenomenon in crop production that soil degradation caused by irrational fertilization reduces crop yield and quality. However, few studies have explored the joint effects of biochar and microbial agents on soil physical and chemical properties and soil microbial diversity. In this study, two Chinese cabbage varieties were used as experimental materials to explore the relationship between the physical and chemical properties of rhizosphere soil, the diversity of soil bacteria, and the growth of Chinese cabbage. The results showed that the best treatment was 24t ha-1 biochar combined with Bacillus subtilis XF-1, which significantly promoted the root growth of Chinese cabbage. Compared with CK, the total root length, root surface area, and root volume increased by 26.0-43.9%, 21.4-37.7%, and 42.3-80.1% respectively, and the yield of Chinese cabbage increased by 9.1% and 15.1% respectively. After biochar application, soil pH, organic matter, total phosphorus, available phosphorus, and available potassium increased significantly compared with CK, and the effect of C1 treatment was the best, increasing by 14.6-18.6%, 105.6%-155.1%, 27.5-33.3%, 67.6-74.8% and 168.8-169.6% respectively. Bacillus application did not affect soil nutrients. Our study also showed that compared with the application of biochar alone, the application of Bacillus subtilis alone and biochar/XF-1 could significantly increase the abundance of Chloroflexi、Acidobacteriota, and Firmicutes. The soil bacterial diversity and richness of biochar/XF-1 were higher than those of other treatments. The combined application of biochar and Bacillus subtilis in soil may be a feasible and effective strategy to promote the growth of Chinese cabbage, improve soil's physical and chemical properties and enrich soil microbial diversity.