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

Abstract

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 μg 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).