Abstract: Nitrate and ammonium leaching from agricultural soil can represent a substantial loss of fertilizer nitrogen (N), but a large variation in losses has been reported. The objectives of this study were to assess the accumulation of NO3¯-N and NH4+-N in the soil profile over a 1-year period under different irrigation and fertilization conditions in sugarcane area of the Khuzestan, Iran. Three irrigation and fertilizer treatments were applied. The first treatment I1 is consisted of full irrigation and others I2 and I3 were 80 and 75% of I1, respectively. N application consist of (N1) 150, (N2) 250 and (N3) 350 kg ha-1. Soil samples were collected from field plots in 0.3 m depth increments to 1.2 m on a periodic basis. NO3¯N values increased with rise of fertilizer consuming and decreasing of water application. It depended to NH4+-N transformation and irrigation regimes. In all treatments, NH4+-N decreased from the surface to 120 cm depth. Maximum concentration of NO3¯N and NH4+-N accrued in I3N3 and I2N3 treatments respectively. This study showed that the moisture was the important parameter because nitrification and denitrification dependent on it and had a direct relationship to nitrate and ammonium accumulation in soil profile.