Carbon dioxide (CO₂) flux from the soil surface can be influenced by soil physical properties due to changes in management practices. The CO₂ flux, soil temperature (T_s), soil water content (θ_v), soil bulk density (ρ_b), and air-filled porosity (E_a) were measured every 1 to 2 wk in no-till (NT) and conventional till (CT) malt barely and undisturbed grass-alfalfa (UGA) systems in a Lihen sandy loam soil (sandy, mixed, frigid Entic Haplustoll) under irrigated and non-irrigated conditions in western North Dakota. Soil E_a was calculated from total soil porosity and q_v measurements. Significant differences in CO₂ fluxes between management systems were observed in some measurement dates. Higher CO₂ fluxes were noted especially in till compared with no-till treatment immediately after a heavy rain or irrigation. A negative correlation between CO₂ flux and E_a (r = – 0.24, P ≤ 0.01) indicated inverse relationship, while positive correlation was found between CO₂ flux and T_s (r = 0.61, P ≤ 0.01). Using stepwise regression analysis, a significant relationship between CO₂ flux and θ_v, T_s, E_a (CO₂ flux = –1.47 +6.29θ_v+ 0.06T_s – 1.6 E_a; R² = 0.50, P ≤ 0.01) was observed. Soil CO₂ flux could be a function of soil temperature, water content, and air-filled porosity due to changes in soil and crop management practices.