EFFECT OF VARIABLE RATE APPLICATION OF FERTILIZERS ON THE NITROGEN USE EFFICIENCY.

The aim of the study was to compare variable rate (VRA) and uniform (UNI) application of mineral nitrogen fertilizers in winter wheat and to evaluate the effect on the achieved yields, nitrogen balance and nitrogen use efficiency (NUE). For these purposes, a field experiment with an area of 16.98 ha of winter wheat was established in 2022 at farm Agra Risuty s.r.o. (Czech Republic, EU). Variable nitrogen topdressing was realized twice during the vegetation period based on yield potential (YP) maps. The evaluation of crop yield maps showed high spatial variability of achieved yield levels within the observed field and their coincidence with the zones of YP. In the case of the UNI variant, the same N rate over all zones led to significant over-fertilization in lessproductive zones in the range of 50 - 70 kg N per ha. This was also reflected by the lower value of NUE for zones with a lower value of YP. The results of the experiment thus point to the importance of the identification of YP zones and the reduction of nitrogen doses in the areas with lower yield productivity to ensure equal nitrogen balance and high NUE. [ABSTRACT FROM AUTHOR]