The paper presents results of fi eld trials, the aim of which was to evaluate the effect of soil supplementation with different forms of nitrogen fertilizers and with magnesium in the modifi cation of generative yield in two different types of maize cultivars. The study determined grain yield at a 15% moisture content, grain moisture content, grain yield components, i.e. the number of productive ears per unit area, thousand kernel weight, number of kernels per ear and the number of kernel rows per ear as well as the number of kernels per row. Moreover, correlation coeffi cients were calculated for correlations between analysed traits. It was shown that the type of nitrogen fertilizer and the dose of magnesium did not differentiate signifi cantly grain water content during maize harvest and grain yield volume. Among analysed nitrogen fertilizers, slow-release fertilizers such as ammonium sulfate, urea and an ammonium nitrate and urea mixture with a 50% proportion of each fertilizer in the component dose proved to be the most advantageous variants in terms of grain yield for the stay-green cultivar. For each of the tested nitrogen fertilizers except for ammonium sulfate the application of 25 kg MgO ha-1 resulted in an increase of grain yield in relation to the treatment where this nutrient was not used. A combined ammonium sulfate fertilization with 25 kg MgO ha-1 reduced grain yield. For both maize cultivars tested in the experiment at each form of nitrogen fertilization and at the absence of fertilization statistically signifi cant positive correlations were found between the number of kernels in the ear and the number of kernels in the row.