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Nitrogen Fertilization for Ethanol Production with Sweet Sorghum and Corn. G. Stevens, R. Holou, M. Rhine and D. Dunn University of Missouri-Delta Center Portageville, Missouri. 60% of U.S. fuel from foreign countries. Fuel versus feed debate. Switchgrass.
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Nitrogen Fertilization for Ethanol Production with Sweet Sorghum and Corn G. Stevens, R. Holou, M. Rhine and D. Dunn University of Missouri-Delta Center Portageville, Missouri
Switchgrass >10 year old stands Missouri Bootheel
Nutrient Partitioning Roland Holou, PhD student November 2007 Fresh wt 4.8 tons/acre Dry wt 3.4 tons/acre
Sweet Sorghum University of Missouri-Delta Center 2007
Subfamily Panicoideae C4 photosynthesis • Sugar cane (Saccharine hybrids) • Sweet sorghum (Sorghum bicolor) • Maize (Zea mays)
WWII Sugar Rationing First & Last 1942- 1947, two years after war ended
Moonshine- sugar from sweet sorghum Cheaper sugar for making ethanol.
Positive Reports that it requires less water and nitrogen than corn. Negative Infrastructure not developed to handle large quantities of juice. Sweet sorghum
Objective • Sweet sorghum- Determine optimum N rates for producing ethanol Irrigated Tiptonville silt loam soil Sweet sorghum– 0, 20, 40, 60, 80, 100, 120 lb N/acre Corn- 0, 40, 80, 120, 160, 200, 240 lb N/acre Sorghum variety: M81E, 4 replications
25 20 15 10 5 0 S Sorghum, fresh wt Corn, bushels per acre S Sorghum, tons per acre dry wt Corn and Sweet Sorghum Yields in 2007 Corn Pounds N per acre
Sweet sorghum stalks, 2008 Fresh weight
Formerly Eastman Kodak Chemical Co. Batesville, Arkansas
Yeast conversion Sucrose + H2O ------ 2 Glucose 342 18 180 6,454 lb sucrose 6,794 lb glucose 2*180= 360
Yeast conversion Fructose + ½ O2 ------ Glucose 164 16 180 354 lb sucrose 389 lb glucose
As lb Glucose Sucrose 6,794 Glucose 414 Fructose 389 Total 7,586 Glucose 2 Ethanol + 2 CO2 180 46 44 Glucose Ethanol 7,586 lb x 2(46) = 3,877 lb 180 587 gal Eth/acre (theoretical) Based on 6.6 lb per gallon Ethanol for sugars 0.511/6.6 = 0.0774 gal Et/lb glucose
Sweet Sorghum Bagasse “chem correct term for cellulose”
Ethanol from cellulose Glucan + H2O Glucose 180/(180-18) = 1.1 lb glucose/lb glucan 2,293 lb x 1.1 x 0.0774= 195 gallons glucan ethanol/acre from cellulose Enzymes- currently too expensive Glucose H2O
Ethanol- loam soil • Ethanol yield from corn with 160 lb N averaged 574 gal/acre • Ethanol yield from sweet sorghum with 60 lb N averaged 528 gal/acre from sugar assuming 90% efficiency. • Max including glucan= 782 gal/acre Corn ethanol estimated 2.8 gal per bushel
Less Productive Soils- 2008 Corn -bushels Sorghum- wet ton
Preliminary Summary • Prime corn land should remain in corn production to supply food and feed. • Sweet sorghum niche for ethanol production may be on marginal soils such as heavy clay and sand. • Because of high cost of cellulose enzymes other uses for bagasse should be explored.