title: Nitrite formation and nitrous oxide emissions as affected by reclaimed effluent application.
abstract: The effect of irrigation with reclaimed effluent (RE) (after secondary treatment) on the mechanisms and rates of nitrite formation, N2O emissions, and N mineralization is not well known. Grumosol (Chromoxerert) soil was incubated for 10 to 14 d with fresh water (FW) and RE treated with 15NO3- and 15NH4+ to provide a better insight on N transformations in RE-irrigated soil. Nitrite levels in RE-irrigated soil were one order of magnitude higher than in FW- irrigated soil and ranged between 15 to 30 mg N kg(-1) soil. Higher levels of NO2- were observed at a moisture content of 60% than at 70% and 40% w/w. Nitrite levels were also higher when RE was applied to a relatively dry Grumosol (20% w/w) than at subsequent applications of RE to soil at 40% w/w. Isotopic labeling indicated that the majority of NO2 was formed via nitrification. The amount of N2O emitted from RE-treated Grumosol was double the amount emitted from FW treatments at 60% w/w. Nitrification was responsible for about 42% of the emissions. The N20 emission from the RE-treated bulk soil (passing a 9.5-mm sieve) was more than double the amount formed in large aggregates (4.76-9.5 mm in diameter). No dinitrogen was detected under the experimental conditions. Results indicate that irrigation with secondary RE stimulates nitrification, which may enhance NO3 leaching losses. This could possibly be a consequence of long-term exposure of the nitrifier population to RE irrigation. Average gross nitrification rate estimates were 11.3 and 15.8 mg N kg(-1) soil d(-1) for FW- and RE-irrigated bulk soils, respectively. Average gross mineralization rate estimates were about 3 mg N kg(-1) soil d(-1) for the two water types.
authors.affiliation: Faculty of Agricultural Engineering, Technion-IIT, Haifa 32000, Israel. master@tx.technion.ac.il
authors.forename: Y
authors.initials: Y
authors.lastname: Master
authors.forename: R J
authors.initials: RJ
authors.lastname: Laughlin
authors.forename: R J
authors.initials: RJ
authors.lastname: Stevens
authors.forename: A
authors.initials: A
authors.lastname: Shaviv
mesh_terms: D000383:Agriculture; D003889:Desert Climate; D009573:Nitrites / Q000032:analysis* / Q000737:chemistry; D009584:Nitrogen / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis*; D012987:Soil; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water; D014881:Water Supply
chemical_list: D009573:Nitrites; D009587:Nitrogen Isotopes; D012987:Soil; D014867:Water; D009609:Nitrous Oxide; D009584:Nitrogen