Basic slag used in this study is a byproduct in the production of steel in electric arc furnaces. Given that the content of P, Fe, Ca, Mg and Mn in the slag is high and those of Cd, Pb, Hg and some other toxic heavy metals is very small, finely ground slag is a potential source of minerals necessary for plant growth and development, especially on iron-poor soils. The aim of this study was to evaluate the effects of steel slag, as a source of specific nutrient elements, on growth and physiological processes of corn and to determine whether steel slag can induce oxidative stress in plant cells. A mixture of earth and sand in different proportions was used as a substrate for planting. Corn seeds were sown in containers and filled with either pure substrate (control) or substrate mixed with finely ground slag. After two weeks, control plants and those grown with the addition of slag were supplemented with NH4NO3 as a source of N. A part of control plants that served as a positive control was supplemented with liquid fertilizers - NPK and Fe. Beside growth parameters, chlorophyll fluorescence, dry matter yield of plants, mineral content in the substrate and plant leaves, chlorophylls and carotenoids content, lipid peroxidation and antioxidant enzyme activities were measured after six weeks of cultivation. The results showed that steel slag is a very good and inexpensive source of microelements especially Fe, Mn and Mg essential to plants and that its usage significantly reduces leaf chlorosis in plants growing on iron-deficient soils.