Ridge–mulch tillage and rotation with broad bean affect soil microbial community, diversity and crop yield in a long‐term potato continuous cropping field

Soil microbial disorder caused by continuous cropping of potato is a major challenge in the semi‐arid region of northwest China. Crop rotation can enhance crop productivity and increase soil microbial diversity. However, the functional significance of changes in soil microbial communities in different ridge‐mulching patterns of potato continuous cropping soil is poorly understood. In view of this, a study was conducted in a 5‐year potato field, to determine the effect of three different tillage practices (nonfilm‐mulched flat plot‐CK, half‐mulched ridge cropping‐T1 and fully mulched ridge cropping‐T2) and two cropping systems (potato‐potato‐C and potato/broad bean‐R) on changes in the microbial community of the soil. The soil microbial community and diversity were examined using the high‐throughput sequencing methods. The dominant bacteria phylum found in the soil was Proteobacteria. The relative abundance of Proteobacteria in fully mulched ridge plots was greater than in half‐mulched ridge and nonfilm‐mulched flat plot. The dominant bacteria genus, Arthrobacter and Planctomyces, were found in the potato–broad bean rotation system, whereas Streptomyces, Steroidobacter and Lysobacter were foremost in the plots under continuous cropping of potato. The dominant phylum of fungi was Ascomycota, and the ratio was increased by film mulching under the continuous cropping system. The relative abundances of dominant genus Monographella, Humicola and Fusarium in the continuous cropping system were higher than that of the rotation system, while Mortierella and Acremonium were dominant in the rotation plots. Moreover, the relative abundance of Humicola and Mortierella was higher in fully mulched ridge plots, while Monographella and Acremonium were higher in the nonfilm‐mulched flat plots. Ridge–mulch tillage and rotation with broad bean could change the composition of soil microbial phylum and genus level, and ridge–mulch tillage may also effect on soil microbial diversity to some extent. Besides, the yields of potato and broad bean under mulched plots were enhanced by 58.03%–73.47% and 70.37%–80.19%, respectively. The yields were greater under fully mulched ridge plots.