The article analyzes the content of selenium in gray forest soils and plants growing on them on the example of the south of Tyumen region. The range of gross selenium content in the arable horizon of gray forest soils of five administrative districts in the south of Tyumen region varies from 0.04 to 0.08 mg/kg and does not differ significantly. Correlations of selenium content with macro- and microelements (gross content, mobile forms) and basic agrochemical indices such as humus, hydrogen index were determined. The greatest influence on the accumulation of selenium in the upper arable horizon of gray forest soil types has copper, zinc, potassium, phosphorus, humus, and pHKCl. The dependence with cobalt, iron, sulfur, nitrate and ammonia nitrogen, calcium, and magnesium is less pronounced. The content of selenium in grain of Triticum aestivum variety Tobolskaya steppe is in the range from 0,003 to 0,092 mg/kg and is characterized as insufficient. The relationships in plant nutrition between selenium and other chemical elements were studied on the example of Triticum aestivum variety Tobolskaya steppe. According to the results of regression analysis, the relationship between selenium and manganese, zinc, copper in grain of spring wheat is characterized by synergism, and in pairs Se–Hg, Se–Cd, Se–As the phenomenon of antagonism is noted. The obtained data can be used to predict the accumulation of selenium in the soil-plant system for specific agro-ecological conditions.