The article considers the method of variable rate application of top dressing with
nitrogen fertilizers in spring barley crops in the system of precise agriculture. The principle of is
based on the in-process diagnosis of plants state in key phases of development and the
introduction of necessary dose of top dressing in specific field areas. To assess the plants state, a
GreenSeeker optical sensor, which measures the NDVI (Normalized Difference Vegetation
Index). The tailored application of top dressing increases the yield of spring barley grain by 14.2%
compared to the application of fertilizers with one calculated rate for the entire plot or field
(Skudra, 2017, Hamann, 2020).