|WILHELM, WALLACE - Former ARS Employee|
|LIGHTLE, DAVE - Natural Resources Conservation Service (NRCS, USDA)|
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2010
Publication Date: 1/4/2011
Citation: Wilhelm, W.W., Johnson, J.M., Lightle, D., Karlen, D.L., Novak, J.M., Barbour, N.W., Laird, D.A., Baker, J.M., Ochsner, T.E., Halvorson, A.D., Archer, D.W., Arriaga, F.J. 2011. Vertical distribution of corn stover dry mass grown at several U.S. locations. BioEnergy Research. 4(1):11-21.
Interpretive Summary: Corn stover is the plant material (leaves, stems and cobs) remaining after the grain is harvested. Stover is a non-food material that can be used to make liquid fuels like ethanol or as a substitute for coal and natural gas. It is important to keep some stover in the field to reduce runoff, minimize soil erosion and replenish soil organic matter. Prototype combines can harvest corn grain and corn stover or harvest corn grain and corn cobs in one pass across the field. The amount of stover that is harvested is controlled by the vertical height of the combine’s cutter blades as it moves through the field. Cutting the plant close to the ground harvests most of the stover and returns very little to the field compared to cutting just below the ears of corn. The height of ears and plant height varies depending on where the crop is grown, the weather and the variety planted. Plant height, dry grain, stover and cob yield data from eight locations (Ames, IA; Auburn, AL; Florence, SC; Fort Collins, CO; Lincoln, NE; Mandan, ND; Morris, MN; and St. Paul, MN) were collected from across the United States to: 1) determine the height distribution of stover biomass; 2) determine the percentage of stover that is corn cob; and 3) develop a general relationship between plant harvest height and stover remaining in the field. This information, though still limited, will significantly improve the capacity of RUSLE2, WEPS and other models to predict erosion risks associated with harvesting corn stover. It will also help ensure the sustainability and feasibility of the fledging biofuels industry in the United States and elsewhere.
Technical Abstract: Corn stover is a likely non-food agricultural feedstock for production of renewable liquid fuels, biopower and other bioproducts. Crop residues serve multiple soil functions such as erosion control and carbon and nutrient cycling. The Revised Universal Soil Loss Equation version 2 (RUSLE2) and the Wind Erosion Prediction System (WEPS) can help estimate corn (Zea mays L.) stover harvest rates that will not exacerbate the risk of erosion. The rate of stover harvest can be controlled through cutting height or selective organ harvest (e.g., grain and cob only). Data are needed from a board range of growing conditions, soil types, hybrids, and regions to develop a robust description of dry stover mass distribution with plant height. Our objectives were to: 1) determine the height distribution of corn stover biomass; 2) determine the percentage of stover that is corn cob; and 3) develop a general relationship between plant harvest height and stover remaining in the field. Plant height, dry grain, stover and cob yield data were collected at eight United States locations. Overall, stover yield increased about 0.85 Mg ha-1 and cob yield increased about 0.10 Mg ha-1 for each 1.0 Mg ha-1 increase in dry grain yield. The stover-to-grain ratio ranged from 0.64 to 0.96 while cob-to-grain ratio ranged from 0.11 to 0.19 at grain harvest. A strong nearly 1:1 linear (r2=0.97) relationship between the relative cutting height and relative biomass remaining in the field was observed across all sites. This information will improve the capacity of the RUSLE2 and similar models to predict the erosion risk of corn residue harvest. [REAP Publication]