THE EFFECT OF NITROGEN NUTRITION ON WINTE R-WHEAT YIELD

In the years 1990 to 1993 in conditions of small-plot field trial was carried out on luvisol at Nitra-Horna Malanta to solve the problems of optimization of nitrogen rates on production and qualitative dressing of winter wheat (the Vlada variety) growing after pea based upon info rmation on N-an content in soil and nitrogen taken by plant (I v an i c et al., 1990) on the basis of nitrogen concentration in plant referr ed to created quantity of above-ground biomass (M i c h a I ik, I, o z e k, 1989) and on the basis of ratio of nutrients in above-ground mas s (B a i e r et al., 1988). During the growing season the uptake of nu trients by winter wheat stand was investigated and the need of differe nt nutrients of the yield of 1 t grain and respective quantity of stra w (30.0 kg N, 4.2 kg P, 16.5 kg K, 4.5 kg Ca, 1.7 kg Mg, 5.1 kg S, 0.6 9 kg Na, O.11 kg Mn, 0.07 kg Zn and 0.02 kg Cu). Differentiated nitrog en nutrition influenced the grain yield, crude protein and starch cont ents statistically significantly. Changes in wet gluten content were i nsignificant. Higher nitrogen rates raised crude protein content and r educed the starch content. In the given soil-climatic conditions posit ive economic effect from applied nitrogen nutrition was obtained only with the lowest nitrogen rates (32 or 38.4 kg.hd(-1), resp.). In these cases coefficient of economic effectiveness (K-ee) was 1.69 or 1.32, coefficient of natural effectiveness (K-ne) was 7.50 and 5.47, coeffic ient of energy effectiveness (K-emerge) was 8.6 and 5.41, profitabilit y of nitrogen fertilization (R) was 68.7 % or 32.2 %, resp., and profi t per 1 ha (Z) was 342 Sk or 179 Sk, resp. Phosphorus nutrition applie d on average of three years (4.4 or 3.3 kg P.ha(-1), resp.) together w ith nitrogen nutrition on analogous treatments reduced economic result by 177 or 676 Sk.ha(-1), resp. Nitrogen rates of 98 and 130 kg.ha(-1) from the point of view of economic effectiveness, profitability of fe rtilization and profit per area unit were inefficient. The results obt ained confirm that optimization of nitrogen rates based on diagnostic methods and information on N-an in soil and nutritive conditions of pl ant make possible to achieve positive financial effect per area unit a nd not to load the environment by nitrogen.