Estimation of net nitrogen flux between the atmosphere and a semi‐natural grassland ecosystem in Hungary

Abstract

The aim of this work is to estimate the net N balance (deposition – emission) between the atmosphere and a semi‐arid, semi‐natural grassland (Bugac station, Central Hungary, CarboEurope IP, NitroEurope IP level 3 site). Dry deposition of N compounds has been determined by the inferential method, based on continuous monitoring of NO2 gas and daily 24‐hour concentration measurements of HNO3 vapour, NH3 gas, and NH4+ and NO3− particles, using dry deposition velocities from the literature, measured above surfaces with the same characteristics as Bugac station. The bi‐directional flux of NH3 within the atmosphere and the canopy (excluding soil emission) has also been estimated by the inferential method. Wet deposition of nitrate and ammonium ions was calculated on the basis of daily precipitation sampling and concentration measurements of nitrate and ammonium ions. To estimate the soil‐atmosphere exchange of different gaseous N forms (N2, NO, N2O, NH3), the DNDC model was used as validated by the chamber measurements of NO and N2O soil emission fluxes. Soil emissions of NO and N2O have been determined by dynamic and static soil chamber methods, respectively. The measurement and modelling activity covers a complete year. Using the measured and modelled data, the calculated N balance at Bugac station between August 2006 and July 2007 is estimated at −8.8 kg N ha−1 year−1 (deposition) as a sum of the deposition and emission terms (−10.4 and 1.6 kg N ha−1 year−1, respectively). Due to the warm and dry weather during the examined period, wet fluxes were substantially lower than usual, which may also have altered the regular yearly course of dry deposition and emission.

Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

“…Samples taken from CH1 and CH3 chambers were analysed according to Vilain et al (2010). Samples taken from CH4 were analysed according to Machon et al (2010). N 2 O fluxes were calculated using the HMR procedure , available as an add-on package for the free programming software R (http://www.r-project.org).…”

Soil-atmosphere relationships: The Hungarianperspective

“…It is to be underlined that simulated fluxes of N 2 O and NO were confirmed by on-site measurements. The agreement between the annual values is good, but the extreme values of daily fluxes deviated significantly from the simulation [52]. Some of these results, together with results referring to CO 2 and CH 4 , were discussed briefly by [105].…”

“…In Hungary, [52] was the first investigation which analyzed the biogeochemical dependence of N 2 O and NO emissions us-ing the well-known DNDC (Denitrification Decomposition) model at Bugacpuszta station [30]. [52,104] analyzed the sensitivity of N 2 O and NO emissions of soil to soil organic carbon (SOC), to mineral nitrogen content (MNC), to microbial activity and to pH-value. Based on their experience, the conclusion is that SOC, MNC and pH-value are the main biogeochemical factors.…”

“…In both cases, the weather events are basically determined by convection, when the land-surface-atmosphere coupling is strong [51]. Bugacpuszta station (46.69 ∘ N, 19.60 ∘ E) is an internationally well known station [52] in central Hungary between the Danube and Tisza rivers. Its edaphic conditions, typical for humous sandy soils, support its semi-arid microclimate, which can be extremely strong in summer.…”

“…Studies treating the effects of biogeophysical factors on trace-gas emission are in the majority [85], but studies focusing on biogeochemical aspects are also common [100][101][102][103]. In Hungary, [52] was the first investigation which analyzed the biogeochemical dependence of N 2 O and NO emissions us-ing the well-known DNDC (Denitrification Decomposition) model at Bugacpuszta station [30]. [52,104] analyzed the sensitivity of N 2 O and NO emissions of soil to soil organic carbon (SOC), to mineral nitrogen content (MNC), to microbial activity and to pH-value.…”