Abstract
This study aimed to examine the effect of adding volcanic slag to soil on the growth, yield, and quality of cucumbers. It also analyzed the changes in the physicochemical properties of the rhizosphere soil, as well as the diversity and structural changes of the bacterial community present in the soil of the cucumber plants. This study used conventional fertilization and cultivation techniques and set up five treatments: HS500, HS1000, HS1500, and HS2000 (representing 500, 1000, 1500, and 2000 kg/ha of volcanic slag added per 667 sq.m in the cultivation trough, respectively), and control (CK; representing 0 kg of added volcanic slag). The Illumina MiSeq System was used to analyze the soil microbial community. The findings revealed that the HS1000 treatment had the most significant promoting effect on increasing cucumber yield, whereas the HS2000 treatment exhibited no significant change compared with the CK treatment. The HS500, HS1000, and HS1500 treatments increased the yield by 12.89%, 24.28%, and 19.56%, respectively, compared with the CK treatment. The HS1000 treatment increased the soluble sugar, vitamin C, and soluble solid contents by 12.39%, 17.57%, and 24.33%, respectively, compared with the CK treatment. The organic matter, total nitrogen, alkali-hydrolyzable nitrogen, nitrate nitrogen, ammonium nitrogen (NH4+-N), available potassium (AK), and available phosphorus (AP) contents in the rhizosphere soil of cucumber plants were the highest under the HS1000 treatment. The alpha diversity analysis revealed that the Chao1, Shannon, and ACE indexes reached the highest under the HS1000 treatment, which were significantly higher than the CK treatment. In contrast, the Simpson index and coverage had no significant changes between treatments. The dominant phyla in each treatment were Proteobacteria, Actinobacteria, and Acidobacteria, among others. The redundancy analysis of soil physicochemical properties and 15 bacterial genera of interest revealed that the available phosphorus, available potassium, and NH4+-N contents were the primary factors influencing the bacterial community in cucumber rhizosphere soil.