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Dryland Performance of Sweet Sorghum and Grain Crops for Biofuel in Nebraska

Sweet sorghum [SS; Sorghum bicolor (L.) Moench] is a potential biofuel crop for the Great Plains. Sweet sorghum was compared
with corn [Zea mays (L.)] and grain sorghum for potential ethanol yield, energy use effi ciency, and greenhouse gas (GHG) emissions
at seven dryland site-years in Nebraska. Seasonal rainfall ranged from approximately 340 to 660 mm. Soils were deep
with medium texture at all site-years. Th e eff ects of seeding rate, N rate, and cultivar on SS performance were evaluated. Sweet
sorghum sugar yield was not aff ected by seeding rate and N application at six of seven site-years, but yield was increased by 19%
at one site-year. Calculated ethanol yield and net energy yield were 33 and 21% more, respectively, with the grain crops compared
with SS, but mean net energy yield of an earlier-maturing SS cultivar was comparable with the grain crops. Th e mean ratio of
energy produced in ethanol per total energy invested was 23% less for grain crops compared with SS. Mean life cycle GHG emissions
were 53% and 66 to 69% less compared with gasoline for SS and grain crops, respectively. Very effi cient use of the ethanol
coproducts was assumed for the grain crops while SS bagasse was assumed to be returned to the fi eld. At least one SS cultivar is
competitive with grain crops for some biofuel criteria, but SS is not competitive with grain crops for total or net liquid transportation
fuel produced per hectare.

Bioenergy Category
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