Abstract:Continuous peanut planting leads to the prevalence of soilborne diseases, and constitutes a serious constraint to the yield and quality. To investigate the biocontrol effects of organic fertilizers on suppressing the soilborne diseases and possible mechanisms, a 6 year field experiment was conducted to study the effects of successive application of chemical fertilizer, organic fertilizer and bioorganic fertilizer (organic fertilizer inoculated with Phomopsis liquidambari B3) on the peanut root rot disease and on the abundance of group specific rhizosphere microbes and enzyme activities. Compared with the single application of chemical fertilizer, successive application of organic fertilizer and bioorganic fertiliaer could effectively control the soilborne diseases, and increased the peanut pod yields by 23.8% and 47.9%, respectively. organic fertilizer and bioorganic fertiliaer applications enhanced the activities of catalase, dehydrogenase and phenol oxidase in rhizosphere soil. The quantitative real-time PCR analysis further detected an increase of the bacterial and fungal abundance, indicating an increase in the soil microbial activities. Organic fertilizer and bioorganic fertiliaer applications also promoted the growth of the beneficial rhizosphere microorganisms, including Actinobacteria increased 0.9- and 1.6-fold, Pseudomonas increased 10.9- and 13.1-fold, Burkholderia increased 2.6- and 1.9-fold, and Bacillus increased 1.1- and 2.1-fold, respectively. However, no significant difference was observed on the abundance of major pathogenic microorganisms, such as Fusarium and Ralstonia solanacearum, two notorious pathogenic microorganisms of peanut between treatments. The above results indicated that successive application of organic fertilizers, especially bioorganic fertiliaer, can control the prevalence of soilborne diseases by increasing the number of beneficial rhizosphere microorganisms and manipulating the soil microbiome to increase soil health.