Protein and Nitrogen Yield Response of Cv. Amisk Feed Barley to Post-Emergence Nitrogen Application in Alberta.

Previous studies report a 25% grain yield gap, and therefore nitrogen (N) yield gap, between actual and attainable rainfed barley (Hordeum vulgare) yields due to management shortfalls in Alberta. High grain protein levels are desirable in feed barley production due to increased feed quality, and increasing N rate has been shown to increase barley protein. Grain protein response to in-season N applied at BBCH 30, the time of maximum crop uptake, is of interest. Commencing in 2014, 10 site years of data were collected, across Alberta, to examine the grain protein and N yield response of cv. Amisk feed barley to post-emergence N application in the form of urea-ammonium nitrate (UAN) at BBCH 30. Spring N fertility rates targeted the area average yield goal, and in-season N treatments were an additional 0, 34, and 64kg N ha^-1. The experimental design was a strip-plot design with post emergence N applied at BBCH 30 as the horizontal strip and seeding rate, plant growth regulator, and fungicide treatments as the vertical strips. Nitrogen response was averaged over all other treatments. Protein response to UAN increased in a linear fashion, by 3.6 and 5.4% compared to control for the 34 and 64 kg N ha^-1, respectively, averaged over sites with average or below average precipitation (p<0.0001). However, where precipitation was highest (426mm inclusive of irrigation), protein decreased by 1.2% but this decrease was offset by a corresponding 7.5% grain yield increase. Post-emergence N application increased grain N yield in a linear fashion across all locations (p<0.0001) by 4.5% and 7.2% at the 34 and 64kg N ha^-1 rates, respectively. In Amisk feed barley grown in Alberta, post-emergence N application at BBCH 30 increases grain N yield and protein, except at high levels of precipitation, where application may result in N yield increases and protein decreases.