Addition of sulphur can increase nitrogen uptake due to synergism between the two nutrients. The aim of this study was to compare the ability of two methods to determine N status of winter wheat (Triticum aestivum, L.) with vegetation indices (VIs) NDVI (normalized difference vegetation index) and NDRE (normalized difference red edge) derived from an active optical sensor (AOS) versus SPAD meter and leaf area index (LAI) measurements. Wheat was grown under different levels of S availability on fields with predominant silty loam and loamy sand soil texture. Plant N status of wheat grown on soil with loamy sand texture was characterized with better effectiveness using VIs than with the use of SPAD and LAI. Stronger variation of NDRE than NDVI values, obtained at the same measurement dates, on both types of soil texture, suggested better usefulness of NDRE for plant N status estimation.
Keywords: winter wheat, nitrogen, sulphur, fertilization, active optical sensor
