This research aims to synthesize a new hydrogel using tragacanth gum with an emphasis on its application in the field of agriculture. For this purpose, tragacanth gum, an eco-friendly polysaccharide, was crosslinked with ethylene glycol under reflux conditions. The effective factors such as temperature, pH, time, and crosslinker content were optimized to maximize the swelling capacity of the product. The synthesized hydrogel was investigated by FT-IR, TGA, FESEM, and XRD techniques. The ability of the hydrogel to save agricultural water was evaluated by measuring water holding and water retention capacity. The effect of the hydrogel on soil fertility was assessed by planting barley seeds in the soil with and without the hydrogel. The optimum conditions for the synthesis of the hydrogel were 0.5 g of tragacanth, 0.02 g of ethylene glycol, at 100 °C, pH 6, and a reaction time of 4 h. The maximum swelling capacity of the synthesized hydrogel was obtained 490 g/g. The results of the statistical analysis showed that there was a significant relationship between the crosslinker content and temperature with the swelling capacity of the synthesized hydrogel (P < 0.05). Also, the presence of the hydrogel in soil showed a significant positive effect on water retention and water holding capacity (P < 0.05). Moreover, adding hydrogel to the soil has a statistically significant effect (P < 0.1) on the average height of the barley sprouts. Therefore, this product can be an effective and promising hydrogel for agricultural applications due to its facile synthesis route and high swelling capacity.