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Crop Residue as Feedstock for the New Bioeconomy: Opportunities and Roadblocks. W. W. Wilhelm USDA-ARS, Lincoln, Nebraska G. E. Varvel USDA-ARS, Lincoln, Nebraska D. L. Karlen USDA-ARS, Ames, Iowa J. M.-F. Johnson USDA-ARS, Morris, Minnesota J. M. Baker USDA-ARS, St. Paul, Minnesota.
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Crop Residue as Feedstock for the New Bioeconomy:Opportunities and Roadblocks W. W. Wilhelm USDA-ARS, Lincoln, Nebraska G. E. Varvel USDA-ARS, Lincoln, Nebraska D. L. Karlen USDA-ARS, Ames, Iowa J. M.-F. Johnson USDA-ARS, Morris, Minnesota J. M. Baker USDA-ARS, St. Paul, Minnesota CSSA Symposium – Feedstock Production for the New Bioeconomy: Opportunities and Roadblocks Crop Science Society of American Annual Meeting, Indianapolis, Indiana November 14, 2006
Billion Ton Report • Biomass production – 1366 million ton • Forestry – 368 million tons • Agriculture – 998 million tons • Perennial energy crops – 377 million tons • Wastes – 87 million tons • Grain – 87 million tons • Crop residues – 428 million tons • Corn stover – 256 million ton
Billion Ton Report • Biomass production – 1366 million ton • Forestry – 368 million tons • Agriculture – 998 million tons • Perennial energy crops – 377 million tons • Wastes – 87 million tons • Grain – 87 million tons • Crop residues – 428 million tons • Corn stover – 256 million ton
Bold, optimistic projections Basis for discussion Lofty target
What is a ONE BILLION? • If one ton = 1 sq in • 1 billion tons = 145 football fields
What is a ONE BILLION? • If one ton = 1 sq in • 1 billion tons = 145 football fields • Agricultural land (cropland plus hay and pasture) • 5 ton ac-1 • 200 x 106 acres • 56% of North Central Region agricultural land • Iowa, Illinois, Nebraska, Minnesota, Indiana, and South Dakota (Total = 195.5 x 106 ac)
Billion Ton ReportAgriculture Assumptions • Yield increase 50% by 2030 • Corn and small grains • Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1 • Machine to recover 75% stover • No tillage adopted universally
25 350 Irrigated contest winners 20 Rainfed contest winners 208 kg ha-1 yr-1 (3.31 bu ac-1 yr-1) 300 250 15 Corn yield (Mg ha-1) 200 Corn yield (bu ac-1) Irrigated average 114 kg ha-1 yr-1 (1.81 bu ac-1 yr-1) 10 150 100 5 50 Rainfed average 89 kg ha-1 yr-1(1.42 bu ac-1 yr-1) 0 0 1965 1975 1985 1995 2005 Corn yield Nebraska contest winners and averages Duvick and Cassman. 1999. Crop Sci. 39:1622-1630. Cassman et al. 2003. Ann. Rev. Envir. Res. 28:-315-356.
USA Corn Yield Trends, 1966-2005 (embodied technological innovation) 12000 Transgenic (Bt) insect resistance 10000 Conservation tillage, soil testing, NPK fertilization Double-X to single-X hybrids 8000 Reduced N fertilizer & irrigation? Grain yield (kg ha-1) 6000 y = 112.4 kg ha-1 yr-1 (1.79 bu ac-1 yr-1) 4000 Integrated pest management r2 = 0.80 Expansion of irrigated area, increased N fertilizer rates 2000 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year Cassman et al. 2006. CAST Report (release Nov. 16, 2006)
Billion Ton ReportAgriculture Assumptions • Yield increase 50% by 2030 • Corn and small grains • Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1 • Machine to recover 75% stover • No tillage adopted universally
Residue:grain in soybean • Low residue production • Longevity of residue • Accelerates decay of SOM • Greater N content of leaves and roots • Rhizodeposits • Large biomass soybean (LBS) • Forage-type soybean • Grain yield not proven • Grain harvest efficiency
Billion Ton ReportAgriculture Assumptions • Yield increase 50% by 2030 • Corn and small grains • Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1 • Machine to recover 75% stover • No tillage adopted universally
Fractional stover harvestISU proto-type harvester * Total residue produced, 10.5 Mg ha-1 Hoskinson et al. 2006. Biomass and Bioenergy (in press).
Billion Ton ReportAgriculture Assumptions • Yield increase 50% by 2030 • Corn and small grains • Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1 • Machine to recover 75% stover • No tillage adopted universally
No tillage adoption(Conservation Tillage Information Center-National Crop Residue Management Survey, 1994-2004, http://lanshark.ctic.purdue.edu/CTIC/CRM.html)
No till with no residue • Runoff occurred sooner • Significant carryover effect of residue removal • Runoff initiated 35% sooner in subsequent year • Sediment concentrations increasing by > 100%. Wilson et al. 2004. Trans. ASAE 47:119-128.
Erosion control • Feed and bedding • Soil amendment • Soil carbon • Plant nutrients Traditional uses of crop residues
Cultivation Stover harvest and Soil carbon Management change Time Soil C change No tillage Cover crops Green manure Pre-cultivation steady-state REAP
Residue needed to maintain SOC REAP Johnson et al. 2006. Agron. J. 98:622-636.
Change allocation of biomass vs. increase total biomass production Increase photosynthetic efficiency 25%, from 4% 5% REAP Long et al. 2006. Plant Cell Envir. 29:315-330.
Multiple biomass Many technologies Conservation Reduced expectations Asking and answering the right question