Chiang Mai Journal of Science

 Consecutive Chinese medicine monocropping used to cause the soil enzyme activities and microbial community composition imbalance and enhanced the pathogen abundances. In this study, the microbial community composition, community structure and enzyme activities were determined in the sanqi uncultivated soil (NS), one-year monocropping soil (FS), and three-year monocropping soil (DS) field in Yanshan County, Yunnan province. With the consecutive cropping years increased, the soil urease activity decreased. After the monocropping, both the rhizosphere soil of FS and DS harbored the distinct bacterial and fungal OTUs, compared to the NS soil. The results showed that the fungal diversity of DS and FS soil significantly decreased in contrast to the NS treatments, while only DS practice significantly decreased the bacterial diversity compare to the FS and NS treatments. The abundance of genus of llyonectria as the pathogen agents increased with the consecutive monocropping year increased. In addition, this genus dramatically enhanced in the DS soil, resulting the imbalance of fungal community composition and structure. Moreover, the abundance of some beneficial bacteria genera in the DS soil significantly decreased in contrast to the NS and FS soil. Taken together, three-year sanqi ginseng consecutive monocropping disrupted the soil microenvironment and harbored a distinct microbial community composition and structure. The niche vacancy of microbial community composition enhanced the abundances of pathogen agents rather than beneficial microorganisms, which could contribute to the replant failure of sanqi ginseng.