Effects of exogenous nitrogen on freshwater marsh plant growth and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi></math> fluxes in Sanjiang Plain, Northeast China: Fid-Bau Portal

Effects of exogenous nitrogen on freshwater marsh plant growth and $N_{2} O$ fluxes in Sanjiang Plain, Northeast China

Zhang, Lihua / Song, Changchun / Wang, Dexuan / Wang, Yiyong

AbstractField management strongly affected the emission of $N_{2} O$ and plant growth from freshwater marshes. Nitrous oxide ( $N_{2} O$ ) fluxes, leaf area, plant height and above ground biomass were investigated under four N treatments (0, 6, 12 and 24g ${NH}_{4} {NO}_{3}$ – $N m^{- 2})$ in the freshwater marshes of Sanjiang Plain, Northeast China. The average growing season $N_{2} O$ flux was $0.065 \pm 0.037$ , $0.086 \pm 0.111$ , $0.141 \pm 0.186$ , $0.445 \pm 0.491 mg m^{- 2} h^{- 1}$ , respectively, the above-ground biomass was $201 \pm 49$ , $252 \pm 40$ , $290 \pm 47$ , $954 \pm 115 g m^{- 2}$ , respectively, the plant height was $66.25 \pm 20.99$ , $71.91 \pm 16.18$ , $73.55 \pm 16.59$ , $84.14 \pm 27.07 cm$ , respectively. Exogenous nitrogen had a significant impact on $N_{2} O$ fluxes and plant growth. Compared to the non-fertilization treatment, the average growing season $N_{2} O$ flux in fertilization increased by 32%, 113%, 581%, respectively, the above-ground biomass increased by 26%, 44%, 375%, respectively, while the plant height increased by 8.5%, 11% and 27%, respectively. A quadratic relationship between the nitrogen applied rate and $N_{2} O$ fluxes, and a non-linear positive correlation between the nitrogen and above-ground biomass were found, while the relationship between the $N_{2} O$ flux and the above-ground biomass was significantly linear positive correlated after nitrogen application, so was the plant height. It was proposed that the exogenous nitrogen gives rise to considerable $N_{2} O$ emissions from freshwater marshes and a large fraction of $N_{2} O$ was emitted to the atmosphere via the transpiration stream within the Deyeuxia angustifolia plants, which provides some quantificational data on the relationship between the nitrogen, $N_{2} O$ fluxes and marsh plant growth.