PHOSPHORUS AND POTASSIUM FERTILIZATION IMPACTS ON YIELD AND NUTRITIONAL STATUS OF MAIZE

The field experiment with three ameliorative rates of P (kg P2O5/ha(-1): 250 = P1, 500 = P2 and 750 = P3). rate of K (500 kg K2O/ha = K2) and their combination (P2K2: 500 kg both P,05 and K2O ha(-1)) was conducted on soil of moderate fertility. Maize was grown for 4-year period 2003-2006. Precipitation and temperature regimes were resposible for considerable differences of maize yield among years. For example, under drought stress of 2003 annualy yield was from 21 to 45% lower than annualy yields for remaining three years. In general, applied fertilization resulted by significant but moderate yield increases for 14% (2003: PK-treatment), 7% (2004: K-treatment), and up to 16% (2005 and 2006: PK and P-3, respectively). K fertilization resulted by decrease of leaf Mg for third part compared to the control. However, for the applied fertilization and the control nutritional status of maize (leaf and grain P. K, Ca, Mg and Zn) remained in normal ranges.