The study was conducted to evaluate the effect of imbalanced mineral fertilization with phosphorus and potassium on calcium and magnesium management in maize at the critical growth stages (BBCH 17 and BBCH 65), as well as the content and accumulation of these nutrients when maize was fully ripe (BBCH 89). A single factor field experiment was established to investigate 8 treatments: the absolute control, without one of the main nutrients (P - WPN or K - WKN), reduced amount of phosphorus and potassium (to 25% - W25 and to 50% - WP50, WK50) and recommended rates of basic nutrients (NPKMg - W100 and NP*KMg, P* - P* as PAPR -W100 PAPR). The results showed no significant effects of mineral fertilization on the calcium and magnesium content in the leaves of maize examined at BBCH 17. Irrespective of mineral fertilization doses applied, Ca and Mg concentrations in maize leaves remained below the standard values. At the next examined maize growth stage (flowering - BBCH 65), magnesium malnutrition was observed as well, whereas the calcium concentration was at the luxury level. Differentiated fertilization with phosphorus and potassium significantly altered Ca and Mg concentrations in the ear leaf of maize at flowering. From the beginning of BBCH 17 stage until the end of maize growth, an antagonism between magnesium and potassium was observed, seen especially distinctively in WKN treatment (no potassium applied). Correlation analysis showed significant relationships between grain yield and plant nutrition with magnesium and calcium at maize flowering. Notwithstanding fertilizer treatments, grain yield of fully ripe maize was determined by the total accumulation of magnesium. More than 50% of Mg total uptake was accumulated in grain. On the other hand, calcium was accumulated mostly in maize stems and leaves, which jointly accumulated 87% of this nutrient.

23.1.2018