Nitrate loss is a major reason for non-point source contamination on agricultural lands. The objective of this study was to assess the Hydrus-1D model for simulation of soil nitrate in different irrigation regimes, including 100 (I1), 85 (I) % of the water requirement for sugarcane and different urea fertilization rates with 150 (N1), 250 (N2), and 350 (N) kg/ha. Van Genuchten (VG) parameters were estimated by the RETC [Retention Curve Program for Unsaturated Soils] program. According to the results, by reducing the amount of irrigation water, the soil nitrate accumulation from the soil surface to the deep soil increased by 17 and 35% under I2 and I3 treatments compared with I. Results showed that the Hydrus-1D model had fair potential for predicting the NO3-N accumulation in the soil profile over the sampling period (AE: −1.25 to 0.99, RMSE: 0.96 to 2.50, d: 0.78 to 0.98). The coefficient of determination between the field measured and simulated values in the soil layers at depths of 30, 60, 90 and 120 cm were 0.87, 0.88, 0.74, and 0.52, respectively. To reduce nitrogen losses, fertilizer application rates must be considered based on sugarcane needs and soil hydraulic properties.
