A soil geochemical analysis was conducted to assess the impact of the exploitation of the Lake Kuchuk salt deposit on the salinization of the soils in the adjacent areas. The specific characteristic of the soil forming in the Kulunda steppe is the wide distribution of salinization processes. Solonetzes soils are distributed in the impact zone of the deposit exploitation; therefore, as background soils, we considered also Solonetzes. Background soils are located at a considerable distance (2–10 km) from industrial facilities. The results of the chemical analysis of the soil-water extracts showed that the area of the most intense salinization is concentrated in the eastern and southeastern parts of the depression of the former lake. Nowadays, a salt evaporation pond and an open salt storage, which are the main industrial sources of sodium sulfate dust, occupy the bottom of the lake. The maximum salt content (over 1%) was found in these parts of the basin and is associated with the prevailing wind direction in the study area. With an increase in the hypsometric level of the surfaces and the distance from the open technological sources of dust, as well as on the opposite slope of the basin, there was a sharp (2–3 times) decrease in the salt content. The total salt content in the background soils ranged from 0.3 to 0.6%. The specificity of the chemistry of soil salinization in the impact zone was the dominance of sulfates and sodium in the composition of the soil-water extract, and thenardite, which is a dehydration product of mirabilite, in the composition of salt crust minerals and salt efflorescences. In the background Solonetzes, the participation of soda in the chemical composition became more noticeable, which is a natural halogen geochemical feature of the Kulunda steppe. In the surface salt crusts in the background areas, a greater variety of minerals were noted, among which there were typical minerals of the evaporite association (gypsum, halite, calcite, dolomite, mirabilite) and their rare species (konyaite, wedellit).