Response of Abundance and Composition of the Bacterial Community to Long-term Fertilization in Paddy Soils

【Objective】The impacts of long-term fertilization on soil microbial community structure and abundance were studied to clarify their relationship and provide a theoretical basis for the soil fertility evaluation and management of rice cultivation.【Method】The soil samples were collected from long-term fertilization experimental plots receiving no fertilization,chemical fertilization,chemical fertilizer + crop residue incorporation.The terminal restriction fragment length polymorphism(T-RFLP) and real-time quantitative PCR analysis were combined to characterize the bacterial community structure and abundance.【Result】Proteobacteria(150 bp;relative abundance 33%—37%) and actinomycetes(67 bp;relative abundance 20%—25%) dominated the bacterial community in paddy soils based on T-RFLP analysis.There was a pronounced difference in the bacterial community composition and diversity responding to the long-term fertilization regimes.CCA results indicated that soil organic carbon(SOC) and pH had the greatest influence on the bacterial community composition.The diversity analysis of Shannon and Evenness Index showed that compared with the unfertilized control,all fertilization treatments significantly increased the bacterial diversity and the harvested residue incorporation also shared the highest.The abundance of bacterial 16S rDNA ranging from 4.34×1010—10.94×1010 copies.g-1soil was determined by real-time PCR,and the amount of 16S rDNA copy number in the fertilization incorporations increased about 50% to 100% of which in unfertilized treatments 【Conclusion】Long-term chemical fertilizer and crop residue incorporation improved soil quality and fertility,and consequently resulted in the shift of the bacterial microecology and promoted the bacterial diversity and abundance.