from a Corn Field under Mediterranean Conditions

Th e use of organic residues as soil additives is increasing, but, depending on their composition and application methods, these organic amendments can stimulate the emissions of CO2 and N2O. Th e objective of this study was to quantify the eff ects of management practices in irrigated sweet corn (Zea mays L.) on CO2 and N2O emissions and to relate emissions to environmental factors. In a 3-yr study, corn residues (CR) and pasteurized chicken manure (PCM) were used as soil amendments compared with no residue (NR) under three management practices: shallow tillage (ST) and no tillage (NT) under consecutive corn crops and ST without crop. Tillage signifi cantly increased (P < 0.05) CO2 and N2O fl uxes in residue-amended plots and in NR plots. Carbon dioxide and N2O fl uxes were correlated with soil NH4 concentrations and with days since tillage and days since seeding. Fluxes of CO2 were correlated with soil water content, whereas N2O fl uxes had higher correlation with air temperature. Annual CO2 emissions were higher with PCM than with CR and NR (9.7, 2.9, and 2.3 Mg C ha−1, respectively). Fluxes of N2O were 34.4, 0.94, and 0.77 kg N ha−1 yr−1 with PCM, CR, and NR, respectively. Annual amounts of CO2–C and N2O–N emissions from the PCM treatments were 64 and 3 % of the applied C and N, respectively. Regardless of cultivation practices, elevated N2O emissions were recorded in the PCM treatment. Th ese emissions could negate some of the benefi cial eff ects of PCM on soil properties