Crop rotation alleviates replant failure in Panax notoginseng (Burkill) F.H. Chen by changing the composition but not the structure of the microbial community

Consecutive monocropping with sanqi (Panax notoginseng (Burkill) F.H. Chen) can increase the abundances of pathogens in soil, resulting in soil sickness. Crop rotation is one way to alleviate this problem. In the present study, there were no differences in microbial structure or bacterial alpha diversity among one-year monocropping soil, one-year rotation soil, and ten-year rotation soil. However, monocropping practices decreased fungal alpha diversity. The relative abundance of copiotrophic bacteria decreased after sanqi monocropping, while that of oligotrophic bacteria increased. Ten-year rotation significantly increased the abundance of potential beneficial bacterial genera. Moreover, the potential beneficial fungal genera were also enriched by rotation for ten years. Furthermore, the relative abundance of Cylindrocarpon spp. decreased dramatically after a ten-year rotation. The results of pot experiments showed that disease incidences after ten-year rotation were significantly decreased among the three treatments. Hence, we suggested that pausing sanqi cultivation for a long time can increase the abundance of potentially beneficial soil bacteria and fungi that are helpful for overcoming soil sickness in sanqi cultivation.