Influence of Biofertilizers on Community Diversity and Population Structure of Soil Bacteria in Cotton Field

【Objective】 To investigate the influence of biofertilizers on community diversity and population structure of soil bacteria in cotton field, reveal how biofertilizers have improved the microbial ecology of soil in cotton field of Xinjiang, and provide a basis for improving the biological control of soil-borne diseases and reducing the application of chemical fertilizers in cotton field. 【Methods】 The soil at the depth of 0-20 cm was collected from the cotton field applying biofertilizers (the experimental group) and the cotton field applying water (the control group). The physical and chemical properties of soil were tested. The bacterial diversity of soil was analyzed by using Illumina Hiseq 2500 PE250 (a high-throughput sequencing platform). 【Results】 After biofertilizers were applied and the application of mixed water fertilizer (the manure of fermented night-soil mixed with water) was suspended, the content of total nitrogen, organic matter and available potassium in soil decreased by 28.7%, 27.5% and 31.9%, respectively. The content of total phosphorus and available nitrogen did not decrease, but the content of total potassium changed a little. The ACE, Chaol and Shannon indexes of soil bacteria in the experimental group had no significant difference from those in the control group after the application of biofertilizers. However, the abundance of soil bacteria decreased significantly after the suspended application of mixed water fertilizer. A cluster analysis indicated that biofertilizers affected the composition of soil microbial community, but their influence decreased when the application of chemical fertilizers was reduced. No significant difference was found in soil bacterial population between the experimental group (the cotton field where biofertilizers were applied and the application of mixed water fertilizer was suspended) and the control group (the cotton field following a conventional management model). The abundance of Bacillus in the experimental group was higher than that in the control group and increased year by year. The abundance of Pseudomonas in the experimental group was lower than that in the control group. The abundance of Lysobacter and Streptomyces did not show a consistent variation tendency. 【Conclusion】 Biofertilizers have no significant effect on the diversity and population structure of soil bacteria in cotton field, but increase the abundance of Bacillus (a kind of beneficial bacteria). It is suggested that biofertilizers should be continuously applied in the cotton farming system of Xinjiang to form a protective layer of microorganisms at rhizosphere and finally maintain a healthy rhizosphere.