title: Nitrous oxide fluxes in turfgrass: effects of nitrogen fertilization rates and types.
abstract: Urban ecosystems are rapidly expanding and their effects on atmospheric nitrous oxide (N2O) inventories are unknown. Our objectives were to: (i) measure the magnitude, seasonal patterns, and annual emissions of N2O in turfgrass; (ii) evaluate effects of fertilization with a high and low rate of urea N; and (iii) evaluate effects of urea and ammonium sulfate on N2O emissions in turfgrass. Nitrogen fertilizers were applied to turfgrass: (i) urea, high rate (UH; 250 kg N ha(-1) yr(-1)); (ii) urea, low rate (UL; 50 kg N ha(-1) yr(-1)); and (iii) ammonium sulfate, high rate (AS; 250 kg N ha(-1) y(-1)); high N rates were applied in five split applications. Soil fluxes of N2O were measured weekly for 1 yr using static surface chambers and analyzing N2O by gas chromatography. Fluxes of N2O ranged from -22 microg N2O-N m(-2) h(-1) during winter to 407 microg N2O-N m(-2) h(-1) after fall fertilization. Nitrogen fertilization increased N2O emissions by up to 15 times within 3 d, although the amount of increase differed after each fertilization. Increases were greater when significant precipitation occurred within 3 d after fertilization. Cumulative annual emissions of N2O-N were 1.65 kg ha(-1) in UH, 1.60 kg ha(-1) in AS, and 1.01 kg ha(-1) in UL. Thus, annual N2O emissions increased 63% in turfgrass fertilized at the high compared with the low rate of urea, but no significant effects were observed between the two fertilizer types. Results suggest that N fertilization rates may be managed to mitigate N2O emissions in turfgrass ecosystems.
authors.affiliation: Dep. of Horticulture, Forestry & Recreation Resources, 2021 Throckmorton Hall, Kansas State Univ., Manhattan, KS 66506, USA. bremer@ksu.edu
authors.forename: Dale J
authors.initials: DJ
authors.lastname: Bremer
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D005069:Evaluation Studies as Topic; D005308:Fertilizers; D007700:Kinetics; D009609:Nitrous Oxide / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism; D012621:Seasons
chemical_list: D000393:Air Pollutants; D005308:Fertilizers; D009609:Nitrous Oxide