Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583
Performing Department
Agronomy & Horticulture
Non Technical Summary
The major feedstocks currently used worldwide for ethanol production are sugarcane (Saccharum officinarum L) molasses in Asia and Africa, sugarcane juice in Brazil, and corn (Zea mays L.) grain in the United States. Sweet sorghum is a potential crop for producing ethanol in the Midwest. The advantage of sweet sorghum compared with corn is that it requires less fertilizer, water, and pesticides and is cheaper to grow. It also does not have the aflatoxin problem that corn for grain does., It has several advantages over sugarcane, such as the ability to withstand dry conditions, require less fertilizer, rapid growth rate, ease of planting, and lower cost of total fermentable sugars. The juice pressed from the stem contains fermentable sugars and thus, the step of breaking down the starch to sugar required in corn and other grains is bypassed. An ideal bioenery crop possesses several characteristics, including the cropping system's productivity, its competition for food, and the environmental impact of expanding acreage of the plant. Ethanol production is a key part of reducing U.S. dependence on foreign oil sources. However, current systems for producing ethanol have a small net energy gain. This is primarily due to the large energy inputs for steam cooking to convert grain starch to sugar and distillation of the ethanol. We propose to develop sweet sorghum (Sorghum bicolor L. Moench) as a bioenergy crop. It has the potential for efficient processing of bioenergy ideally suited to the Nebraska farm system, especially for the drought susceptible central and western parts of the state. In areas typically affected by drought, sweet sorghum out-produces corn in carbohydrate production; Nebraska must incorporate into its strategic plan for bioenergy the inevitability of future water limits. To address these challenges, our objectives are: . 1. To compare the yield and production efficiency of SS to corn or grain sorghum for ethanol production across a range of dryland environments and to develop N management and planting guidelines for SS production in Nebraska. 2. To determine total biomass production and ethanol potential from sweet sorghum However, certain barriers currently limit the attractiveness of sweet sorghum, a resilient crop, as biomass resource for bioenergy in the U.S. Most of these barriers center on optimizing performance of the crop on marginal lands, developing avenues to permit efficient conversion of the remaining biomass to ethanol, and developing better technologies for harvesting and separating sap from fiber.
Animal Health Component
50%
Research Effort Categories
Basic
20%
Applied
50%
Developmental
30%
Goals / Objectives
1. To compare the yield and production efficiency of SS to corn or grain sorghum for ethanol production across a range of dryland environments and to develop N management and planting guidelines for SS production in Nebraska. 2. To determine total biomass production and ethanol potential from sweet sorghum
Project Methods
Objective #1. Research will be conducted at five site-years in Nebraska The sweet sorghum trials consist of a factorial design of N rates, plant density, and variety. The N rates are 0, 45, and 90 kg ha-1 surface applied as Agrotain. The plant density treatments are 75,000, 125,000 and 175,000 viable seed per hectare. The sweet sorghum varieties will be Keller and M81E in 2010 and Simon and M81E in 2011. These varieties were selected from a set of generally old varieties introduced to Nebraska for performance in eastern Nebraska. Sweet sorghum harvest consists of cutting the stalks at 8-10 cm from the ground in a single row of 3 m length and harvested stalks were counted. Harvest will be at the dough stage for Simon but near anthesis to early milk and shortly before or after killing frost for the late maturity M81E and Keller. Fresh biomass wt. will be obtained. Brix will be determine for six stalk segments per plot with segments taken along the length of the stalks. Ten to 12 stalk segments, with leaves, will be collected, weighed wet, oven-dried, and weighed dry to determine the juice content after correcting for leaf wt. Corn and grain sorghum yield will be determined from ear and panicle harvest from two rows of 6 m length which will be weighed and sub-sampled to determine shelling and threshing percentage The analyses of variance for agronomic data will be conducted using Statistix 9 (Analytical Software, Tallahassee, FL). Replication effects will be considered random and all treatment effects will be considered fixed. Differences will be considered significant at P ≤ 0.05. Estimation of ethanol-equivalent yield, GHG emissions, and energy balance The Biofuel Energy Systems Simulator (BESS; Liska et al., 2008; available at www.bess.unl.edu) will be used to calculate ethanol-equivalent yield. Default values of BESS will be used for the conversion of grain to ethanol and for estimation of CO2e emissions, and energy balance. Objective #2. Four cultivars of sweet sorghum (M81E, Dale, Keller, and Simon) will be selected to include a wide range of maturities, morphologies, and breeding histories. These cultivars were developed at various location, several of these are dual-purpose forage and syrup cultivars. Sorghum will be planted in late April into a prepared seedbed at a rate of 2 Kg per hectare and depth of 2 cm. Row spacing will be 30 cm. Sorghum plots will be randomly subdivided into two subplots that will be harvested at different times: 1) mid September to allow time for establishment of a subsequent winter annual crop, and 2) after frost to determine season-long biomass accumulation. Plots will be harvested with a silage chopper to determine biomass yield and sub-samples will be collected and analyzed to determine concentrations of moisture, ash, nonstructural carbohydrates, structural carbohydrates, lignin, total carbon, and total nitrogen. Theoretical EtOH yields will be calculated by dividing total sugar yield (Mg/ ha) by 5.68 kg, which is equivalent to 12.51 Ibs of sugar per gallon of EtOH.