Effect of long-term fertilization on bacterial composition in rice paddy soil

We investigated the effect of long-term fertilization on bacterial abundance, composition, and diversity in paddy soil. The experiment started in 1990 in Taoyuan Agro-ecosystem Research Station in China (111A degrees 33' E, 28A degrees 55' N). The molecular approaches including real-time quantitative PCR, terminal restriction fragment length polymorphism, and clone library construction were employed using 16S rRNA gene as genetic marker. Application of inorganic fertilizers did not affect bacterial abundance, and rice straw incorporation combined with inorganic fertilizers significantly (P < 0.05) increased bacterial abundance with shifts in bacterial community composition. Among phylogenetic groups, gamma-Proteobacteria was responsive to all fertilization regimes while Acidobacteria was relatively stable to fertilization practices. Inorganic fertilizer mainly affected gamma-Proteobacteria and delta-Proteobacteria, while rice straw incorporation influenced beta-Proteobacteria and Verrucomicrobia. Therefore, long-term fertilization can affect abundance and composition of bacterial communities in paddy soil.