Uncoated Vs. Polymer Coated Urea on Barley in Southeast Idaho.

Efficient nitrogen (N) management is essential to a barley fertilization program. Nitrogen management affects barley yield and protein concentration. Environmentally Smart Nitrogen (ESN) is a dry granular coated urea made from a patented process engineered to control the release of N based on soil temperatures. Increasing soil temperatures result in higher release rates and associated plant growth. The objective of this study was to evaluate flag leaf N concentrations and grain yield and protein content for various N fertilizer rates applied pre-plant using coated (ESN) and/or uncoated urea. Barley was planted at the Brigham Young University-Idaho Hillside Farm in Rexburg, ID. Treatments included all combinations of three pre-plant N rates and three source combinations. There was a general response to N fertilizer, with the greatest response at the first increment of N fertilization. The split ESN and urea at 75 lb N/ac gave the greatest yield increase. The 100% of either urea or ESN also resulted in yield increases, but at a lower yield level. The next increment of N at 100 lb N/ac gave a similar response, although with less total yield for all source combinations. Again, the split urea and ESN treatment gave the greatest yield increase over the control and was greater than all other treatments in the trial excepting the same source combination at the lower N rate of 75 lb N/ac. However, the 100% applications of either ESN or urea actually resulted in yield decreases relative to the control. The highest increment of N at 125 lb N/ac had even larger yield decreases. These results suggest some of the N from urea was lost to volatilization, leaching, or denitrification, and having a combination of some N immediately available along with some controlled release N is the best combination. Flag leaf N concentrations increased with higher N rates while having greater concentrations using ESN than urea. There were no differences in grain protein across any treatment—even the unfertilized control—all having moderately high levels. Further studies are needed to evaluate the protein and yield response to ESN in barley. One possible option for future studies, which would have helped in this situation, would be to apply 50% of the N as ESN pre-plant and then use tissue analysis to determine the rate of urea to be applied in-season.