Field experiment was carried out in the Didactic and Experimental Department in Swadzim near Poznań, in years 2004-2005 (52^o26’ N; 16^o45’ E). The experiment was established in a „split-plot” design with two factors and four field replications. The primary factor consisted in three nitrogen doses: 0, 60, and 120 kg N·ha^-1, while the secondary factor included four doses of kieserite (magnesium sulphate): 0 kg fertilizer·ha^-1, 100 kg fertilizer·ha^-1 (25 kg MgO·ha^-1 + 20 kg S·ha^-1), 200 kg fertilizer·ha^-1 (50 kg MgO·ha^-1 + 40 kg S·ha^-1), and 300 kg fertilizer·ha^-1 (75 kg MgO·ha^-1 + 60 kg S·ha^-1). It was found that the fertilization of maize with kieserite in the dose of 300 kg of fertilizer per ha does not generate any disturbances in the correct germination of maize seeds and that such a dose level is not toxic to maize plants. The level of nitrogen fertilization differentiated the dry matter of a single plant and the dry matter yield of plants in the phase of 5-6 leaves (BBCH 15-16), as well as the yield of the dry matter of ears and of the whole plants. The size of kieserite dose differentiated the dry matter yield of stover, ears, and whole plants. Uptake of nitrogen, potassium, and calcium in the phase of 5-6 leaves (BBCH 15-16) increased with the increasing doses of nitrogen. Fertilization of maize with nitrogen in the dose of 120 kg N·ha^-1 with kieserite increased the yield of plant dry matter and nitrogen uptake in the above mentioned yield of plants in the phase of 5-6 leaves (BBCH 15-16). The level of nitrogen fertilization differentiated the chlorophyll content expressed in SPAD units in the phase of 5-6 leaves (BBCH 15-16); however, in the ear blooming phase (BBCH 67), the value of this feature was modified by the level of the doses of nitrogen and kieserite.

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