Measurement of ammonia exchange over grassland in the Hungarian Great Plain

@article{citeulike:2855187, abstract = {The net dry flux of ammonia gas was measured between the atmosphere and a semi-natural grassland with low nitrogen input in Hungary, during the years of 2000 and 2001. A continuous flow denuder system was used to detect the ammonia concentrations at three levels (0.5, 1.0 and 2.0 m above the vegetation). Fluxes were calculated by the aerodynamic gradient method. According to the measurements, the net dry ammonia flux in the vegetation period is 0.37 kg N ha-1 (emission) and -5.0 kg N ha-1 (deposition) in the dormant season. For comparison the total atmospheric (dry + wet) input is -9.2 kg N ha-1 year-1 including all nitrogen forms and excluding ammonia. Net emission was observed only at daytime during the vegetation period when the canopy concentration exceeded the atmospheric ammonia concentration, due to an elevated stomatal compensation point. In all other times (night-time, outside the vegetation period) net deposition flux was observed. A sudden increase of N-input (application of 100 kg N ha-1 fertiliser) resulted in a large enhancement in emission during daytime, which lasted for 2-week period after the application of fertiliser, when the accumulated N-loss (emission factor) of fertiliser was amounted to approximately 1.3\%. During night-time week deposition was detected from the fertilised sector suggesting that ammonia is emitted mainly by the plant through stomata in daytime, rather than from the soil. Measured fluxes have been compared to the prediction of a single layer compensation point model. The agreement is good, but some challenges remain for the selection of the parameterisation for individual model parameters.}, author = {Horv\'{a}th, L\'{a}szl\'{o} and Asztalos, M\'{a}ria and F\"{u}hrer, Erno and M\'{e}sz\'{a}ros, R\'{o}bert and Weidinger, Tam\'{a}s }, citeulike-article-id = {2855187}, doi = {http://dx.doi.org/10.1016/j.agrformet.2005.04.005}, journal = {Agricultural and Forest Meteorology}, keywords = {ammonia, nh3\_flux, nh3\_model}, month = {June}, number = {3-4}, pages = {282--298}, posted-at = {2008-06-01 18:24:15}, priority = {5}, title = {Measurement of ammonia exchange over grassland in the Hungarian Great Plain}, url = {http://dx.doi.org/10.1016/j.agrformet.2005.04.005}, volume = {130}, year = {2005} }

TY - JOUR ID - citeulike:2855187 L3 - citeulike-article-id:2855187 N2 - The net dry flux of ammonia gas was measured between the atmosphere and a semi-natural grassland with low nitrogen input in Hungary, during the years of 2000 and 2001. A continuous flow denuder system was used to detect the ammonia concentrations at three levels (0.5, 1.0 and 2.0 m above the vegetation). Fluxes were calculated by the aerodynamic gradient method. According to the measurements, the net dry ammonia flux in the vegetation period is 0.37 kg N ha-1 (emission) and -5.0 kg N ha-1 (deposition) in the dormant season. For comparison the total atmospheric (dry + wet) input is -9.2 kg N ha-1 year-1 including all nitrogen forms and excluding ammonia. Net emission was observed only at daytime during the vegetation period when the canopy concentration exceeded the atmospheric ammonia concentration, due to an elevated stomatal compensation point. In all other times (night-time, outside the vegetation period) net deposition flux was observed. A sudden increase of N-input (application of 100 kg N ha-1 fertiliser) resulted in a large enhancement in emission during daytime, which lasted for 2-week period after the application of fertiliser, when the accumulated N-loss (emission factor) of fertiliser was amounted to approximately 1.3%. During night-time week deposition was detected from the fertilised sector suggesting that ammonia is emitted mainly by the plant through stomata in daytime, rather than from the soil. Measured fluxes have been compared to the prediction of a single layer compensation point model. The agreement is good, but some challenges remain for the selection of the parameterisation for individual model parameters. IS - 3-4 JF - Agricultural and Forest Meteorology EP - 298 TI - Measurement of ammonia exchange over grassland in the Hungarian Great Plain VL - 130 SP - 282 KW - ammonia KW - nh3_flux KW - nh3_model AU - Horváth, László AU - Asztalos, Mária AU - Führer, Erno AU - Mészáros, Róbert AU - Weidinger, Tamás PY - 2005/06/30/ UR - http://dx.doi.org/10.1016/j.agrformet.2005.04.005 ER -