Nitrous Oxide Fluxes in Turfgrass

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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 μg N2O-N m−2 h−1 during winter to 407 μg 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. Copyright © 2006. American Society of Agronomy, Crop Science Society of America, Soil Science Society . ASA, CSSA, SSSA
Funding Information
  • National Science Foundation (EPS‐0236913)