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Correct application of nitrogen fertilizers in crop management on arable land has high importance both from economic and environmental point of view, mainly in the condition of higher spatial variability of farm fields. One of the solutions could be a variable rate application (VRA) of nitrogen fertilizers based on the management zones, which addresses site specific changes in soil properties and crop requirements. The main aim of this study was to analyze the spatial variability of two fields from crop yield maps and to evaluate benefits of VRA for topdressing of winter wheat crop stand by ISARIA sensor system. Experimental work was carried out at two fields (43.9 and 69.8 ha) on farm enterprise Spearhead Czech located in Zdounky (Kromeriz, Czech Republic) in 2016 and 2017. For assessment of spatial heterogeneity of fields, crop yield maps recorded by harvesters were used and analyzed in Geographic Information System (GIS). Variable application of nitrogen fertilizers was realized for second (N2) and third (N3) topdressing nitrogen application in winter wheat by proximal sensing system Fritzmeier ISARIA. This system evaluates nitrogen status of plants by measuring of spectral response in visible and near infrared wavelengths (vegetation indices IBI and IRMI) and immediately changes application rates on spreader. The results of yield maps analysis showed that values of crop yield varied from 5.55 to 11.53 t.ha-1 in 2016 and from 4.86 to 14.30 t.ha-1in 2017. However, coefficient of variability was in both cases under 10 % (8.26 % in 2016, 9.97 % in 2017). Uniform application of nitrogen according to the average crop yields would lead to underdosing of N rates on 6.27 % of area in 2016 (15.04 % in 2017) and overdosing on 11.05 % in 2016 and 14.83 % in 2017. Summary of applied fertilizers by ISARIA system showed that in 2016 only 14.36 % of area was applied by average N rate in second application (N2) and 26.78 % of area in third application (N3). In 2017 the values differ – 74.56 % of area was covered by average N2 dose and 61.78 % of area in N3. It can be concluded that distribution of nitrogen doses by variable application has positive effect on the nitrogen use for specific crop yield level and on the reduction of environmental risks by nitrogen losses. [ABSTRACT FROM AUTHOR]