Activity and composition of the denitrifying bacterial community respond differently to long-term fertilization
长期施肥制度对稻田土壤反硝化细菌群落活性和结构的影响

The objective of this study was to explore the long-term effects of organic and inorganic fertilizers on activity and composition of the denitrifying communities in paddy soil. The soil samples were collected from the following treatments: CK (no fertilizer), NPK (nitrogen, phosphorus and potassium fertilizers) and NPKOM (NPK plus organic matter), which were established in 1990. The activity was measured in terms of potential denitrification rate and narG gene was used as the functional marker of the denitrifying community. The results showed that the potential denitrification rate was higher in plot treated with organic fertilizer than in those with mineral fertilizer and no fertilizer, and this finding was positively correlated to soil organic matter content, MBC, and MBN. Totally 35 OTUs were obtained and identified as narG from the three treatments. Recovered narG sequences were mainly grouped in two clusters and related to narG gene of the denitrifiers from Proteobacteria and Actinobacteria.The LUBSHUFF statistical analyses demonstrated that narG gene library of NPKOM treatment was significantly different from CK, while no significant difference was found between NPK and CK, NPK and NPKOM treatments. It inferred that the combined application of chemical and organic fertilizers remarkably influenced the community composition of narG-containing bacteria.