N2O emissions from two Mediterranean agricultural soil with similar sub-optimal irrigation regimes and different N-input management

In the last decades the increased N-input and the large use of irrigation, have greatly increased N2O emissions from croplands (IPCC, 2007). Scanty data are available about N2O effluxes from irrigated croplands of Mediterranean countries, despite the extension of these areas and their potential as high N2O emitters via bacterial denitrification and/or nitrification, due to the combined effect of irrigation and high soil temperature, especially after N fertilization (Sanchez et al., 2001; Vallejo et al., 2004). Indeed irrigation appears to play a key role in the evolution of N2O from cropped soil under Mediterranean condition and recently it has been underlined (Sánchez-Martín et al., 2008) that the reduction of the amount of water applied and the optimization of its distribution into the soil profile can effectively mitigate N2O emission from Mediterranean irrigated cropland The aim of this study was to investigate the influence of sub-optimal irrigation scheduling on nitrous oxide emissions from the soil of two Mediterranean irrigated croplands under different N-input. Mineral N availability played a key role in the evolution of N2O from soil, as evidenced by the total N2O-N emissions - which were more than doubled in BC compared with TL. Overall low values for N2O efflux from soil and N2O emission factor were detected at both sites, despite the highest N input supplied at BC. Fhese findings confirm that a proper management of irrigation can restrain N losses from Mediterranean agroecosystems, reducing N2O production by soil microbial processes.