title: Effects of ferric iron reduction and regeneration on nitrous oxide and methane emissions in a rice soil.
abstract: A laboratory soil slurry experiment and an outdoor pot experiment were conducted to study effects of ferric iron (Fe(III)) reduction and regeneration on nitrous oxide (N(2)O) and methane (CH(4)) emissions in a rice (Oryza sativa L.) soil. The anoxic slurry experiment showed that enhancing microbial Fe(III) reduction by ferrihydrite amendment (40 mol Fe g(-1)) transitionally stimulated N(2)O production and lowered CH(4) production by 16% during an initial 33-day incubation. Increased regeneration of Fe(III) through a 4-day aeration period in the Fe-amended slurry compared to the control slurry reduced CH(4) emission by 30% in the subsequent 15-day anaerobic incubation. The pot experiment showed that ferrihydrite amendment (63 micromol Fe g(-1)) stimulated N(2)O fluxes in the days following flooding. The Fe amendment suppression on CH(4) emission was obscured in the early season but became significant upon reflooding in the mid- and late-seasons. As a result, seasonal CH(4) emission in Fe-amended pots was 26% lower than the control with a single 2-day drainage and 69% lower with a double 2-day drainage. The reduction in CH(4) emission upon reflooding from the Fe-amended pots was mainly attributed to the increased Fe(III) regeneration during drainage showing a mechanism of Fe(III) regeneration in mitigating CH(4) emission by short-term drainage in flooded soils.
authors.affiliation: Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA. bhuang3@lsu.edu
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.forename: Kewei
authors.initials: K
authors.lastname: Yu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Gambrell
mesh_terms: D005290:Ferric Compounds / Q000032:analysis / Q000737:chemistry*; D055868:Floods; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000032:analysis* / Q000378:metabolism; D009609:Nitrous Oxide / Q000032:analysis* / Q000378:metabolism; D012275:Oryza / Q000378:metabolism*; D010084:Oxidation-Reduction; D012987:Soil; D012988:Soil Microbiology
chemical_list: D005290:Ferric Compounds; D012987:Soil; C092844:ferric oxyhydroxide; D009609:Nitrous Oxide; D008697:Methane