RESIDUAL INFLUENCES OF PHOSPHORUS FERTILIZATION ON MAIZE STATUS IN POTKOZARJE AREA

The field experiment with four rates of phosphorus (P) fertilization was conducted in spring of 2004 with treatments as follows: a) ordinary fertilization (kg ha-1: 200 N + 80 P2O5 + 120 K2O); b) a + 500 kg P2O5; c) a + 1000 kg P2O5; and d) a + 1500 kg P2O5. In the next three years (2005-2007) only ordinary fertilization was applied and residual effects of applied fertilization were tested. Drought and high-temperature stresses were main factors of maize yield dropping for the 2007 growing season because it was even 60% lower than in the previous year (means 3.41 and 7.63 t ha-1, respectively). Under these conditions it was not found effect of applied fertilization However, under favourable conditions of the 2006 growing season, residual effects of P fertilization resulted by yield increases up to 20%. Also, maize responded on the P fertilizations by yield increases up to 32% and 17%, for 2004 and 2005, respectively. Residual effects of P fertilization on leaf nutritional status was found (testing for 2006 only). For example, leaf P, K Cu, and Cd were increased (for 11%, 7%, 25% and 53%, respectively: status on the control 0.33% P, 1.93% K, 13.1 mg Cu and 0.172 mg Cd kg-1). At the same time, leaf Mg, Mn, Cr, B, Ba and Al were decreased (for 14%, 13%, 16%,31%,25% and 28%: status on the control = 0.146% Mg, mg kg-l = 37.3 Mn, 0.28 Cr,4.41 B, 2.8 Ba and 47.8 Al). For remaining tested elements (Ca, S, Zn, Fe, Mo, Ni,SR, Na and Co) differences were nonsignificant. Grain composition was less depended on fertilization and only for four tested elements significant differences were found as follows: increasing influences for S (+17%), Zn (+25%) and Ni (+54%) and decreasing influences for Sr(-15%)- status on the control - 0.78% S, 20.0 mg Zn, 0.94 mg Ni and 0.69 mg Sr kg-1).