Atmospheric inorganic nitrogen in dry deposition to a typical red soil agro-ecosystem in southeastern China

Atmospheric dry deposition is an important pathway of nitrogen (N) sources input to agro-ecosystems. With the knowledge of increasing agricultural effects by dry N deposition, researchers have paid great attention to this topic. Characteristics of dry N deposition were estimated by a big-leaf resistance analogy model and the Auto-Meteorological Experiment Station (AMES) in a typical red soil agro-ecosystem in southeastern China for two years (2005-2006). Monthly dry deposition velocities (V-d) were in the range of 0.16-0.36, 0.07-0.17 and 0.07-0.24 cm s(-1) for NH3, NO2 and aerosol particles (aerosol NH4+ or NO3-), respectively, and the V-d were higher in spring and winter than in summer and autumn. Monthly dry N deposition concentration (C-a) and inferred deposition flux (F-d) were in the range of 63.38-261.10, 47.21-278.92, 1.56-7.15, 47.21-278.92 mu g N m(-3) and of 1.31-8.60, 0.38-3.67, 0-0.08, 0.01-0.23 kg N ha(-2) for NH3, NO2, aerosol NH4+ and aerosol NO3-, respectively. During the study period (2005-2006), the total dry N deposition was 70.55 kg N ha(-1) yr(-1) which equivalent to 1.53.8 kg (urea) ha(-1) yr(-1) or 415.0 kg (ammonium bicarbonate) ha(-1) yr(-1) applied in the red soil agro-ecosystems. In addition, the annual mean N depositions, mean sum of the monthly N depositions were 69.44, 1.12, 53.95 and 16.60 kg N ha(-1) yr(-1) for gaseous N, aerosol N, ammonia N and oxidized N, making up 98.42%, 1.58%, 53.95% and 16.60% of the total dry deposition N (70.50 kg ha(-1) yr(-1)).