Atmospheric nitrogen deposition in the Loess area of China

Özet

We present the quantification information on atmospheric nitrogen (N) deposition in the Loess area in Yangling District of Shaanxi Province, China using combined methods of a long-term field measurement (2006e2012), a potted experiment (2009e2011) and a long-term site-specific experiment (1991e2008). Our results showed that the annual deposition fluxes of dissolved inorganic N (NH4 þ N and NO3 N) via both precipitation (wet-deposition) and dustfall (dry-deposition) ranged from 12.73 to 37.87 kg N ha1 yr1 and averaged 21.76 kg N ha1 yr1 , with large contributions from wet deposition. The annual mean ratios of deposition amounts of ammonium N (NH4 þ N) to nitrate N (NO3 N) were less than 1 in all the study years with an exception of the year 2007. Based on crop N uptake (approximately 52 kg N ha1 yr1 ) in the pot experiment, it was estimated that the dry N deposition fluxes (including gas and particles) was about 23.81 kg N ha1 yr1 , accounting for 45.8% of the total N deposition. According the long-term site-specific experiment, the contribution of N input to farmland from the atmosphere was estimated to account for 52.8% of the environmental N input. Our results suggested that atmospheric N deposition was an important N input that must be taken into consideration when calculating nutrient budgets in agricultural ecosystems.