Responses of N2O reductase gene （nosZ）-denitrifier communities to long-term fertilization follow a depth pattern in calcareous purplish paddy soil

摘要

cqvip:The effect of long-term fertilization on soil denitrifying communities was analysed by measuring the abundance and diversity of the nitrous oxide(N_2O)reductase gene,nos Z.Soil samples were collected from plots of a long-term fertilization experiment established in 1982 in Suining City,China.The fertilizer treatments were no fertilizer(CK),three chemical fertilizer(CF)treatments(N,NP,NPK),manure(M)alone,and manure with chemical fertilizers(NM,NPM,NPKM).The abundance and diversity of the denitrifying bacteria were assessed by real-time quantitative PCR,terminal restriction fragment length polymorphism(T-RFLP),and cloning and sequencing of nos Z genes.The diversity and abundance of nos Z-denitrifiers was higher in soil amended with manure and chemical fertilizers(CFM)than in soil amended with CF alone,and the highest in topsoil(0–20 cm).The nos Z-denitrifier community composition was more complex in CFM soil than in CF soil.Specific species were detected only in the CFM soil.The abundance of nos Z-denitrifier in the NPKM treatment was approximately two times higher than that in the CK,N,and NPK treatments.Most of the cloned nos Z sequences were closely related to nos Z sequences from Bradyrhizobiaceae and Rhodospirillaceae in Alphaproteobacteria.Of the measured abiotic factors,soil organic matter correlated significantly with the abundance(P<0.01);available phosphorus correlated significantly with the topsoil community composition(P<0.01),whereas soil organic matter correlated significantly with the subsoil(20–90 cm)community composition(P<0.01).This study demonstrated that long-term CFM fertilization affected both the abundance and composition of the nos Z-denitrifier community.