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Crop and ethanol yield and nitrogen use efficiency of high biomass sorghum


High biomass sorghum could potentially produce high yields in the U.S. Midwest with minimal fertilizer inputs. However, little is known about its yield response, N uptake, nitrogen use efficiency (NUE), and nitrogen recovery efficiency (NRE) at varying N fertilization rates when grown for lignocellulosic ethanol. 

In a recent study reported in Agronomy Journal, researchers at the University of Missouri applied five rates of N urea fertilizer (0-224 kg N ha-1) to two varieties of High Biomass Sorghum in two years. They were interested in not only determining biomass yields, but also theoretical ethanol yield, N recovery efficiency (NRE), and N use efficiency (NUE).

No biomass yield differences were observed between the two varieties in either year, but yields and N-related measures differed with the distinct weather conditions between the two years.

One year, marked by adverse weather events, they found no differences in yield or other N-related measures in response to N rate—including no N fertilizer.  In the other year, they found no difference in yield among N fertilized treatments, but yields were greater than when no N was applied. The NRE was greatest at 56 kg N ha-1, 60% greater than at the highest N rates (168 and 224 kg N ha-1). Nitrogen use efficiency remained high across all N rates.

Given the typically variable weather in this region and the lack of differences in yield and N-related measures, the data suggest that these sorghum varieties can be grown with limited N inputs and are suitable for marginal lands.

Read the full article in Agronomy Journal. Free preview Feb 17- Feb 24