title: The effects of stubble retention and nitrogen application on soil microbial community structure and functional gene abundance under irrigated maize.
abstract: The effects of agronomic management practices on the soil microbial community were investigated in a maize production system in New South Wales, Australia. The site has been intensively studied to measure the impact of stubble management and N-fertilizer application on greenhouse gas emissions (CO(2) and N(2)O), N-cycling, pathology, soil structure and yield. As all of these endpoints can be regulated by microbial processes, the microbiology of the system was examined. Soil samples were taken after a winter fallow period and the diversity of the bacterial and fungal communities was measured using PCR-denaturing gradient gel electrophoresis. Stubble and N shifted the structure of bacterial and fungal communities with the primary driver being stubble addition on the fungal community structure (P<0.05 for all effects). Changes in C, N (total and NO(3)), K and Na, were correlated (P<0.05) with variation in the microbial community structure. Quantitative PCR showed that nifH (nitrogen fixation) and napA (denitrification) gene abundance increased upon stubble retention, whereas amoA gene numbers were increased by N addition. These results showed that the management of both stubble and N have significant and long-term impacts on the size and structure of the soil microbial community at phylogenetic and functional levels.
authors.affiliation: CSIRO Land and Water, Glen Osmond, Adelaide, SA, Australia.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Wakelin
authors.forename: Matt J
authors.initials: MJ
authors.lastname: Colloff
authors.forename: Paul R
authors.initials: PR
authors.lastname: Harvey
authors.forename: Petra
authors.initials: P
authors.lastname: Marschner
authors.forename: Adrienne L
authors.initials: AL
authors.lastname: Gregg
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Rogers
mesh_terms: D000383:Agriculture; D001315:Australia; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D016000:Cluster Analysis; D015180:Electrophoresis, Gel, Two-Dimensional; D005308:Fertilizers; D005658:Fungi / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000235:genetics; D016133:Polymerase Chain Reaction; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D003313:Zea mays
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen