Continuous cropping of alfalfa (Medicago sativa L.) reduces bacterial diversity and simplifies cooccurrence networks in aeolian sandy soil

Alfalfa is a perennial herbaceous forage legume that remarkably and negatively affected by monocropping. However, the contribution of changes in bacterial communities to soil sickness alfalfa have not been elucidated. Therefore, we investigated community structures response monocropped along chronosequence. Continuous cropping reduced alpha diversity altered structures, pH, total P available were strongly associated with structures. Intriguingly, 10 years might be demarcation point separating into two obvious groups containing samples collected less more than years. The relative abundances copiotrophic bacteria Actinobacteria Gammaproteobacteria significantly increased extension continuous years, while oligotrophic Armatimonadetes, Chloroflexi, Firmicutes Gemmatimonadetes showed opposite changing patterns. Among those phyla, Actinobacteria, Alphaproteobacteria Acidobacteria most important which contributed 50.86% variations. Additionally, nitrogen fixation Bradyrhizobium Mesorhizobium obviously Arthrobacter, Bacillus, Burkholderiaceae Microbacterium potential functions solubilizing phosphorus potassium decreased after long-term cropping. Furthermore, cooccurrence patterns influenced simplifying complexity networks. These findings enhanced our understandings provided references for forecasting how responds alfalfa.