The paper demonstrates the inhibitive effect of inorganic and organic additives to calcium nitrate and ammoniated calcium nitrate aqueous solutions on corrosion of low carbon structural steel St3. The steel corrosion behavior was studied by voltammetry. The effect of ammonization as well as of addition of such inhibitors as monoethanolamine and potassium dichromate on the main parameters of the corrosion process was established. The findings will be useful for corrosion control in components made of the steel used in fertilizer industry and also in concrete as reinforcement.