Restructuring Tilth Layers Can Change the Microbial Community Structure and Affect the Occurrence of Verticillium Wilt in Cotton Field

Restructuring tilth layers (RTL) is a tillage method that exchanges the 0–20 and 20–40 cm soil layers that can be applied during cotton cultivation to increase cotton yield, eliminate weeds and alleviate severe disease, including Verticillium wilt. However, the mechanism by which RTL inhibits Verticillium wilt is unclear. Therefore, we investigated the distribution of microbial communities after rotary tillage (CK) and RTL treatments to identify the reasons for the reduction of Verticillium wilt in cotton fields subjected to RTL. Illumina high-throughput sequencing was used to sequence the bacterial and fungal genes. The disease incidence and severity of Verticillium wilt decreased by 28.57% and 42.64%, respectively, after RTL. Moreover, RTL significantly enhanced bacterial richness and evenness at 20–40 cm and -reduced the differences in fungal evenness and richness between soil depths of 0–20 and 20–40 cm. The number of Verticillium dahliae decreased, while the relative abundance of biocontrol bacteria such as Bacillus and Pseudoxanthomonas increased significantly following RTL. Overall RTL improved bacterial diversity, decreased the number of Verticillium dahliae and increased the relative abundance of biocontrol bacteria, which may have suppressed the occurrence of Verticillium wilt in cotton fields.