Abstract
Nitrogen (NI) is essential for tiller formation and development of kernels in spring barley (Hordeum vulgare). In order to address the issue of growing N fertilizer prices and better N management practice field trials were conducted in three locations at the University of Idaho R&E centers for two growing seasons (2021-2022). Three classes of spring barley i.e., feed, malt, and food were planted at 50, 101, 151, 202 kg N per hectare for feed and malt barley and 0, 34 67, 101, 134 kg N per hectare for food barley. It measured the effect of N fertilizer rates on Grain Yield (GY), Nitrogen Uptake (NUp) and Nitrogen Use Efficiency (NUE). Nitrogen rate and variety had a highly significant effect on grain yield. A higher N rate was also associated with a bigger N uptake. In two of the three locations, significant differences in N uptake for all the varieties were observed. N rate affected NUE in one of the three locations for both trial periods. Another study utilized ground sensors and aerial sensors to predict GY and NUp. Normalized vegetative differences index (NDVI) and Chlorophyll Content Index (CCI) were recorded at tillering and flowering stage using GreenSeeker (GS), unmanned aerial vehicle (UAV) mounted sensor, SPAD meter, and MC-100 meter respectively. We observe a highly significant effect of the N rate on GS NDVI readings. GS was also found to be better than SPAD meter, MC-100 and UAV at predicting Grain Yield (GY) and Nitrogen Uptake (NU).