Progress 08/20/02 to 08/19/07
Outputs
Progress Report Objectives (from AD-416) 1) To develop cost-effective methodologies for harvesting, fractionation, densification, transport, and storage of crop residues used for value- added products and/or bioenergy. 2) To maintain biomass quality, from field to processing, that is consistent with end use. Project to be extended in time so that material placed in storage in Fall 2006 can be stored for at least 6 months to ferment, & then removed & analyzed for changes in physical & chemical properties. This material will also serve as a feedstock for work on rheological & compression properties. Approach (from AD-416) Corn stover, the most abundant crop residue in the U.S., has been selected as the model crop residue. A number of challenges must be surmounted to deliver this material to a processing plant for $30-35 per ton dry basis. These challenges include: 1) minimal interference with grain harvest; 2) relatively high moisture content; 3) relatively low per- acre tonnage (sustainable yields may be 40-70% of total stover, depending on soil and topography); 4) low density as harvested, leading to high transport costs; and 5) necessity of storing the material harvested during one month for processing during a 12-month period. Fractionation of the stover, e.g., into pith, rind, leaves, and cob, may increase its total value by tailoring fraction properties to specific end uses. Significant Activities that Support Special Target Populations This report serves to document accomplishments under a Specific Cooperative Agreement (SCA) between ARS and the University of Wisconsin- Madison. Additional details of research can be found in the parent project 3655-41000-004-00D: �Value-Added Products from Forages and Biomass Energy Crops.� Research on the harvesting, processing, and storage of corn stover was carried out by Dr. Kevin Shinners, University of Wisconsin-Madison. Work continued on reducing stover cost through the development of single-pass harvesting equipment. Single-pass harvesting creates two separate crop streams, grain and stover, in a single harvesting pass. Field evaluations made in the fall of 2006 showed that the flail chopper used to size reduce the stover at the rear of the harvester was creating a flow bottleneck and absorbing excess power. Therefore, engineering design changes were made to improve material flow and particle-size reduction at the rear of the combine for the 2007 harvest season. These changes include a rear converging auger to gather the stover; a new mechanism to control, meter and precision-cut the stover; and a new blowing mechanism. The cutting system and blower can be easily removed from the combine, and the converging auger used to lay a windrow of stover onto the ground using a two-pass harvesting system. This windrow could be chopped with a forage harvester or baled after field drying. Crop placed into storage in the fall of 2006 was removed in late summer 2007 for evaluation of storage characteristics, fuel conversion potential, and transport requirements. Stover fractions stored for later evaluation included whole-plant, stalk-leaf, and cob-husk. Monitoring of the SCA was achieved through approximately biweekly telephone conversations and emails between ADODR and Cooperator, and by semiannual submission of reports by the Cooperator to the ADODR.
Impacts
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Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and the University of Wisconsin-Madison to provide engineering expertise. Additional details of research can be found in the report of the parent project 3655-41000-004-00D: "Value- Added Products from Forages and Biomass Energy Crops." Research on the harvesting, stability under storage and subsequent fractionation was carried out on corn stover by Dr. Kevin Shinners, Department of Biological Systems Engineering, University of Wisconsin-Madison. A grain combine was modified to produce single-pass, whole-plant corn harvesting with two crop streams, grain and stover. Three heads for the combine were investigated in 2005. The conventional ear-snapper head allowed capture of the cob, husk and some leaves from the rear of the harvester. A stalk- gathering head captured the stalk, leaf and some husk at the front of the harvester while the
cob and husk was captured separately from the rear. A whole-plant head allowed harvest of all the stover fractions from the rear of the harvester. Capture of potential stover DM was 30, 67 and 90% of DM for a combine harvester configured with an ear-snapper, stalk- gathering and whole-plant heads, respectively. Stover aggregate moisture was 51.0 and 52.5% (w.b.) for the whole-plant and stalk-gathering heads (front wagon only), respectively. Aggregate moisture of stover from the ear-snapper and stalk-gathering heads (rear wagon only) was 38.5% (w.b.). When the stalk-gathering or whole-plant heads were used, greater stover feedrate limited ground speed, so area capacity was 3.4, 2.2, and 2.0 ha/h, for the ear-snapper, stalk-gathering and whole-plant heads, respectively. Wet and dry bulk density was 163 and 100; 147 and 70; and 80 and 38 kg/m3 for the ear-snapper, stalk-gathering and whole-plant heads, respectively. Fall and spring untilled ground cover was greater than the minimum
requirement of 30% with all three heads. Chisel plowing in the fall with twisted shovels buried too much residue no matter the head type. Only the use of the whole-plant head would have left insufficient residue cover when chisel plowed with sweeps in the spring. Fermentation of single-pass stover in a bag silo was very good with DM losses after eight months of storage of 4.1 and 6.7% for the material harvested with the whole-plant and stalk-gathering heads, respectively.
Impacts
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Publications
- Shinners, K.J., Boettcher, G.C., Munk, J.C., Digman, M.F., Muck, R.E., Weimer, P.J. 2006. Single-pass, split-stream of corn grain and stover: characteristic performance of three harvester configurations. Proceedings of the Annual Meeting of the American Society of Agricultural and Biological Engineers International. Paper No. 061015. p. 1-19.
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Progress 10/01/04 to 09/30/05
Outputs
4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and the University of Wisconsin-Madison to provide engineering expertise. This project has been extended to 03/31/2006. Additional details of research can be found in the report of the parent project 3655-41000-004-00D: "Value-Added Products from Forages and Biomass Energy Crops." Research on the harvesting, stability under storage, and subsequent fractionation was carried out on corn stover by Dr. Kevin Shinners, University of Wisconsin-Madison. A grain combine was modified to produce single-pass, whole-plant corn harvesting with two crop streams, grain and stover. Capture of potential stover dry matter (DM) varied from 48 to 89% for leaves, 49 to 92% for stalks, and greater than 90% for husks and cobs, depending upon corn head height. Stover aggregate moisture was 50.2, 43.1, and 36.4% (weight basis)when the corn head height was 10, 44, and 63%
of ear height, respectively. Greater MOG feed rate limited ground speed due to power availability, so area capacity was 2.3, 2.8, and 3.4 ha/h when corn head height was 10, 44, and 63% of ear height, respectively. Whole-plant harvesting reduced area capacity by nearly 61% compared to harvesting with a conventional snapping-roll head. Single-pass stover had an average particle size of 69 mm and bulk density of 51 and 110 kg DM/m3 in the wagon and bag silo, respectively. Aggregate stover samples were dried, ground, and scanned in a near infrared reflectance spectrometer sensor, and spectra were collected. Spectra were submitted to the National Renewable Energy Laboratory for determination of chemical composition-based Stover9 calibration. Based on polymeric sugar content, estimated ethanol yield was 3,945, 3,230, and 2,600 L/ha when the corn head height was 10, 44, and 63% of ear height, respectively. Fermentation of single-pass stover in a bag silo was adequate with average
losses of 6% of total DM.
Impacts
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Progress 10/01/03 to 09/30/04
Outputs
4. What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a specific cooperative agreement between ARS and the University of Wisconsin-Madison to provide engineering expertise. Additional details of research can be found in the report of the parent project 3655-41000-004-00D: "Value- Added Products from Forages and Biomass Energy Crops." Research on the harvesting, stability under storage, and subsequent fractionation was carried out on corn stover by Dr. Kevin Shinners, University of Wisconsin- Madison. Experiments with different corn hybrids grown in separate fields revealed that stover and grain content varied substantially with moisture stress, and that in dry years successful preservation by ensiling could be challenged. Four different methods of harvesting under dry conditions yielded desired low-moisture content of the stover, but exposure to any significant rain during harvest
prevented an acceptable level of drying, regardless of treatment, unless a raking operation was also employed, which resulted in significant increases in ash content of the stover. Storage experiments revealed that stover (47% moisture) stored 7 months in a silo bag displayed only slight molding at the bag/air interface, a pH of 5.1, and a loss of 10.6% of dry matter. In contrast, tube-wrapped bales at 40% moisture displayed no molding, a pH of 5.1, and a loss of only 3.6% of dry matter. The data suggest that low- moisture anaerobic storage may be superior to ensiling in reducing dry matter losses. Experiments with dry bales revealed that dry matter losses depended on baling procedures (net wrap < plastic twine < sisal twine) and storage environment (indoor < outdoor). Additional experiments examined the feasibility of hydrodynamic separation of the grain and stover following ensiling of chopped corn plants. Segregation of the grain fraction reached 75% under low-moisture conditions
(36% dry matter), but declined to 41% under high-moisture conditions (26% dry matter). Air drying of the silage increased the segregation of the grain to 99%. The data provide guidance on harvesting and storage methods to producers who harvest corn for either food or bio-ethanol applications.
Impacts
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