ИСТИНА

Based on the results of fertilization trials with winter wheat on sod-podzolic soils , we have analysed agronomical benefits and environmental threats of increasing N rates in the mineral and mixed organic-mineral fertilizer systems with Nitrogen Use Efficiency (NUE) approach. A safe N rates are within 100−150 kg·ha-1 for mixed organic−mineral fertilization system and 120-180 kg·ha-1 for a mineral fertilization system. The study also demonstrates the applicability of the NUE indicator for connecting N efficiency and yield sustainability. A noticeable decrease in variation between years in N output occurs when the input is >100 kg·ha-1, suggesting increasing N fertilization in improving yield sustainability. At the same time, for winter wheat growing technologies of 70-80s last century as well for the modern ones rates > 250 kg·ha-1 demonstrate N excess and higher environmental N losses.