Potential of Optical Sensors for Predicting Winter Wheat Yield Through Variable-Rate Nitrogen Application

Summary The main lever of precision agriculture is technology that provides a better understanding of the agro-ecological conditions, enables decision-making based on facts and natural laws, and facilitates precise implementation of practices based on local specificities. One of the key elements of plant production is nitrogen (N), which is traditionally applied as mineral fertilizer in large quantities. Optimizing nitrogen input is one of the priorities in precision agriculture, not only for its importance in the plant food chain but also for its environmental impact. This study investigated the potential of two optical sensors, GreenSeeker and Plant-O-Meter, in predicting nitrogen supply during the 2021-2022 growing season. The experimental material in this study included two wheat varieties, subjected to different nitrogen application rates. The objective was to estimate the potential of using NDVI (Normalized Difference Vegetation Index) measurements of wheat canopy, which are indicators of plant status, and to analyze correlations between these values and final wheat yield. GreenSeeker and Plant-O-Meter sensors, which emit light at precise wavelengths and measure plant reflectance, were used for monitoring plant status and NDVI measurements. The results showed a strong correlation between the NDVI values measured by both sensors. However, this relationship decreased during the fully ripe stage due to physiological changes in the wheat plants. The correlation between NDVI values and grain yield differed significantly between the evaluated sensors. Additional correlation analyses between NDVI measurements and yield indicated differences associated with wheat varieties, indicating that the varieties responded differently to environmental conditions. This study aligns with current agricultural approaches and contributes to more efficient and environmentally friendly agricultural practices.