Spanish Journal of Agricultural Research 13(1), e09-002, 9 pages (2015)

ciency levels. High nitrate concentrations have been measured in drainage return flows from maize fields and this crop has been recently recognized as one of the main contributors to nitrate pollution of surface and ground waters (Cavero et al., 2003; Causapé et al., 2004a; Isidoro et al., 2006) in the Ebro river basin. Several irrigated areas in the basin have been de-clared vulnerable to nitrate leaching by Regional gov-ernments following the EU Directive (EC, 1991). In those areas, action programs impose limitations to the amounts of N fertilizer that can be applied to crops, Utility of the end-of-season nitrate test for nitrogen sufficiency of irrigated maize under Mediterranean semi-arid condition