THE EFFECT OF NITROGEN NUTRITION ON WINTER-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 information 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 referred 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 mass (B a i e r et al., 1988). During the growing season the uptake of nutrients by winter wheat stand was investigated and the need of different nutrients of the yield of 1 t grain and respective quantity of straw (30.0 kg N, 4.2 kg P, 16.5 kg K, 4.5 kg Ca, 1.7 kg Mg, 5.1 kg S, 0.69 kg Na, O.11 kg Mn, 0.07 kg Zn and 0.02 kg Cu). Differentiated nitrogen nutrition influenced the grain yield, crude protein and starch contents statistically significantly. Changes in wet gluten content were insignificant. Higher nitrogen rates raised crude protein content and reduced the starch content. In the given soil-climatic conditions positive 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, coefficient of energy effectiveness (K-emerge) was 8.6 and 5.41, profitability of nitrogen fertilization (R) was 68.7 % or 32.2 %, resp., and profit per 1 ha (Z) was 342 Sk or 179 Sk, resp. Phosphorus nutrition applied on average of three years (4.4 or 3.3 kg P.ha(-1), resp.) together with 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 fertilization and profit per area unit were inefficient. The results obtained confirm that optimization of nitrogen rates based on diagnostic methods and information on N-an in soil and nutritive conditions of plant make possible to achieve positive financial effect per area unit and not to load the environment by nitrogen.