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Background and Objectives: nutrient deficiency is one of the common problems in world's soils, especially calcareous soils. Hence, application of new ways including slow release fertilizer is increasing to improve the nutritional status of nutrients. Therefore, the present study was carried out to investigate the effects of hydrogel and nitrogen on soil chemical properties, yield, concentration and uptake of nitrogen in Mentha in a calcareous soil and under greenhouse culture. Materials and Methods: This research was conducted in a complete randomized design with three replications. The treatments were included hydrogel in levels of 0, 0.005 and 0.01% of soil and urea fertilizer in level of 100, 200 and 300 kg.ha-1. During the experiment, chlorophylln a and b were measured. At the end of the experiment, soil chemical properties such as pH, dissolved organic carbon (DOC), soil nitrogen, and yield and some physiological characteristics of Mentha were measured. Results: The results showed that the lowest pH, the maximum of DOC and soil nitrogen was obtained in level of 0.01% of hydrogel treatment. The maximum yield of Mentha was obtained in level of 0.01% of hydrogel treatment. The utilization of hydrogel and nitrogen fertilizer had a considerable impact on the nitrogen concentration and uptake. Conclusions: The results of this study showed that the use of hydrogel in the amount of 0.01% by weight and 200 kg/ha of urea can have a useful and effective role in improving nitrogen uptake in Mentha. Based on these experimental results, it could be concluded that the increase in the amount of nitrogen in the Mentha plant was due to the increase in the amount of nitrogen in the soil and as a result, better uptake and impact on yield. The utilization of hydrogel in combination with chemical fertilizers is an effective approach to mitigate environmental issues associated with the use of chemical fertilizers. [ABSTRACT FROM AUTHOR]