One of the most important factors in agriculture production is sufficient amount of nutrients available for plants and among these nutrients nitrogen is very important. The waste of this nutrient causes groundwater pollution to ammonium and nitrate. Fertilization methods play an important role in the water and fertilizer use efficiency, crop yield and fertilizer losses. Considering above matter, experiment was conducted in randomized block design with respect to time with eight replications for each treatment on sugar beet crop. The experimental treatments consisted of two fertilizer application methods including treatment “a” which the fertilizer is applied by irrigation and treatment “b” which the fertilizer is sprayed by hand. For treatment “a”, 580 kg urea was applied gradually with irrigation water during growing season and for treatment “b”, half of this amount of urea was applied before germination and another half was applied at the middle period of growing season. Nitrate samples were taken from soil at depths of 25, 50 and 75 cm at three different times during growing season. Results showed that the method of fertilizer application on soil nitrate at soil depths of 25 and 75 cm is significant at 1% level. This effect was not significant at soil depth of 50 cm. The effect of time of sampling on soil nitrate was significant at 1% level for all three soil depths and the highest value was belonged to treatment “b” at soil depth of 25 cm for the beginning of the growing season with value of 94.4 mg per kg soil and the lowest value was belonged to treatment “b” at soil depth of 25 cm for the end of the growing season with value of 17.8 mg per kg soil. The highest and lowest amount of nitrate in treatment “b” is because of higher leaching in fertilizer application by hand method as compared with the gradually application of fertilizer by irrigation water and this shows that the danger of groundwater pollution in this treatment is high. The remained nitrate in the soil for treatment “a” for all three soil depths at the end of season was similar to the beginning of the season and shows that there is good agreement between applied nitrate to soil and crop nitrate absorption. Effect of trial blocks on soil nitrate was not significant at any soil depth. The average sugar beet yield of treatment “a” with value of 67,843 kg per hectare was greater than treatment “b” with value of 57,274 kg per hectare. Proper management of fertigation in trickle irrigation causes higher yield and less nitrate leaching in soil profile. Keywords: Fertilizer, Nitrogen, Nitrate, Sugar Beet, Trickle irrigation, Yield