Shallow (non-inversion) tillage (ST) alters the distribution, relative to moldboard ploughing (MP), of soil properties such as bulk density, soil organic matter and microbial populations. Soil moisture may interact with these properties and thereby affect the course of nitrogen turnover across the soil profile. This laboratory experiment examined effects of ST and MP on nitrate accumulation, N2O emissions and denitrification in two soil types. Intact soil cores (100 cm3) were taken at 0-4 and 14-18 cm depth in each tillage treatment. Six replicates per soil, tillage treatment and depth were adjusted to one of seven soil water potentials ranging from -15 to -1500 hPa. Following measurement of gas diffusivity (relative to diffusion in air) and permeability, the samples were incubated at 20°C. Ceramic discs were used to determine soil nitrate prior to incubation. Carbon dioxide evolution and N2O emission were recorded after 10 and 31 d. Half of the replicates were then used for determination of denitrification activity and subsequently subsampled for denitrifying enzyme activity; the other half was subsampled for potential ammonium oxidation. All replicates were analyzed for mineral N and pH after 31 d. Nitrous oxide emission peaked at -30 to -60 hPa in the loamy soil, but at -15 hPa in the sandy loam. When related to relative gas diffusivity, an upper threshold of 0.02 was suggested for both N2O emission and denitrification. Both respiration and nitrate accumulation declined at the drier end of the water potential range employed. In soil under ST management, potential process rates, respiration and nitrate accumulation were elevated and pH reduced at 0-4 cm depth across all water potentials and both soil types. This may reflect a more intense N turnover that could be important for the crop N supply in case of detrimental soil compaction below the depth of shallow tillage.