The effect of N-fertilization, fertilizer type and cropping systems on trace gas emissions from agricultural soils under rain fed agriculture has been widely reviewed. However, there is little information concerning trace gas fluxes from the semi-arid irrigated soils in the Pacific Northwest. Potato production in sandy irrigated soil with intensive fertilization is a common practice in eastern Washington. This agricultural management practices may increase yield but may also influence trace gas (CO₂, N₂O, and CH₄) production and consumption. Research findings, using indirect N-budget estimates, suggest greater loss of applied N fertilizer either through nitrification-denitrification or/and volatilization in irrigated sandy soils. The study was conducted in 2005 on Quincy Sandy soil (Mixed, Mesic Typic Torripsamments) using center pivot irrigation system cropped to sweet corn and potato (potato-corn-corn rotation) with 336 kg N ha^-1  (112 kg N ha^-1 at pre-plant and 224 kg N ha^-1 in-season fertilizer application) and tillage practices (conventional and reduced tillage). Fluxes were measured an hour after fertigation, using vented chambers, every week during the cropping season (May 24 through August 24, 2005) and monthly for the rest of the year. Methane uptake in the native site was 193 g of CH₄-C ha^-1 and it is on an average 1.5 times more than in the potato and corn fields. The oxidation of methane in the native shrub steppe site acts as terrestrial sink and accounts 0.23% of the C emitted as CO₂. The emission rates of N₂O and CO₂ were higher at time of fertigation and no significant differences were observed between crops and tillage practices. Cumulative, CO₂ and N₂0 fluxes from corn and potato fields were 14 and 22 times greater than the native site, respectively for the growing season.  N₂0-N losses accounted for 0.2% (0.5 kg N ha^-1) of the applied fertilizer (224 kg N ha^-1).