Ammonia volatilization from urea application under Mediterranean climate

The use of fertilizers benefits the crop via an increased availability of nitrogen (N), but it also enhances N mobility in the soil and groundwater, leading to losses, such as ammonia (NH3) emissions in atmosphere and nitrate (NO3-) leaching from to ground and surface water (Galloway et al., 2004). The accumulation of reactive nitrogen in terrestrial ecosystems might lead to environmental issues (Galloway et al., 2003). To reduce the adverse environmental impact of increased fertilizer usage and to optimize the efficiency of applied N, a quantification of the nutrient losses involved in the nitrogen (N) cycle is required. In particular, NH3 losses due to volatilization following application of both organic and mineral fertilisers have long been studied over a wide range of ecosystem (i.a. Sutton et al., 1993), but few studies are found relative to semi-arid conditions adopting a the micrometeorological approach (Rana and Mastrorilli, 1998; Sanz-Cobena et al. 2008). In this work, the eddy covariance (EC) method (i.a. Kaimal and Finnigan, 1994) was used under Mediterranean conditions for monitoring NH3 volatilization following urea spreading, and quantitative relationships could be found between emission and bio-physical variables.