Carneiro, J.P.Coutinho, JoãoTrindade, Henrique2014-10-222014-10-222014CARNEIRO, J.P. [et al.] (2014) - Nitrogen use efficiency in a soil amended with different organic residues. In Nitrogen Workshop, 18, Lisboa, 30 junho-3 julho - The nitrogen challenge : building a blueprint for nitrogen use efficiency and food security : proceedings. Lisboa : ISA. p. 48-49. Comunicaçãohttp://hdl.handle.net/10400.11/2581Nitrogen efficient use is important for economic and environmental sustainability of cropping systems. Three examples of fertilization practices considered to be able to contribute to the improvement of N use efficiency are: the use of a waste with higher C/N ratio, such as pulp mill sludge (Kirchmann and Bergström, 2003), specific application time and/or split application of nitrogen fertilizers (Roberts, 2008) and the use of nitrification inhibitors, such as the DCD (Zaman and Blennerhassett, 2010). In present study a field experiment was carried out from May 2006 to May 2008, in central Portugal, to evaluate agronomic nitrogen use efficiency (AE) and apparent N recovery efficiency (ARE), when different organic wastes (cattle slurry, sewage sludge and urban waste compost) were used as N sources in a double-cropping system producing maize and oats forage. The use of a nitrification inhibitor (DCD), the splitting application of residues and the use of an organic residue with high C/N ratio (pulp mill sludge) were evaluated as management practices that could improve N use efficiency.engNitrogen efficiencySoilconference object