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Greenhouse Gas Emissions from U.S. Livestock Production Systems D. Johnson, H. Phetteplace, A. Seidl Colorado State University
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Outline, AN448,Sept. 22, 2004 I. Global greenhouse gas accum II. Agriculture and livestock role III. Livestock system sources IV. Manure system GHG’s V. Mitigation strategies
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References: Agric GHG’s IPCC, 2001 (06): GHG Inventory Good Practice Guidelines (ipcc-nggip.iges.or.jp) USEPA, 2004: Inventory of US GHG (yosemite.epa.gov/oar/globalwarming) USDA, 2004: US Agric. & Forestry GHG (usda.gov/oce/gcpo) Proc. Agstar Conf. Anaerobic Digestion (epa.gov/agstar/conference04)
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SOURCE: IPCC
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SOURCE: Science, 1-11-2002
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Global Climate Changes (IPCC) Snow cover: 10% decrease Glacier retreat: major River and lake ice: 2 wk decrease Sea ice extent: 10-15% decrease Arctic ice thickness: 40% decrease Diurnal temp range: decrease Tropospheric water, clouds: increase
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SOURCE: IPCC
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GHG Sources in US (as CO 2 equivalent) CO 2 CH 4 x 21 N 2 O x 310
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Importance of Non-CO 2 GHG’s Why bother? Globally – 40% Effective fast Cost effective Political feasibility Synergy-other problems Climate Forcings of GHG’s, CO2eq in US, 2002, %
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Agriculture’s Role, cont’d 70% of Nitrous oxide 30% of Methane Huge C-sequestration potential
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Agriculture sources of GHG (USDA, 04)
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Global N-input Sources (Mosier and Kroeze, 99)
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Products and GHG from Cattle Production J W Herd 100 cows + others Cropping Feeds Manure CH 4 N 2 0 Fuel C0 2 Soil Carbon ( + )
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Beef System GHGs CO 2 eq by Gas Source (100 cow US system) Gas t/yr CV CH 4 221 4 N 2 O308 10 CO 2 66 17 Cseq -53 18 Total: 542 7
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GHG Sources by Beef Sector ( CO 2, N 2 O, CH 4 as CO 2 eq)
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Dairy System GHGs (100 cow herd, t/yr) GasCalifWisc CH 4, enteric320292 CH 4, manure185 18 N 2 O331298 CO 2 254274 C-sequest 0 (28) Total 1090 854
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Waste GHG, Beef Cattle
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Waste, Dairy Cattle
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Waste, Swine
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Biological N transformations (Nitrification-Denitrification) NH 4 NH 3 NO 2 - N2ON2O NO 3 - NO 2 - NO N2ON2O N2N2 N2ON2O Nitrification Denitrification Aerobic Anaerobic
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Manure methane equations Livestock characterization and pop. Waste characteristics Waste management system usage Methane conversion factor (MCF) EPA, 2002, 04
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Manure methane emissions Kg CH 4 /yr by state for each animal group CH 4 an grp = Σ(pop. x VS x B o x MCF x 0.662) pop = avg head animal group for each state VS = VS in kg/head/year B o = max CH 4 prod capacity/kg VS MCF = weighted MCF for animal group by state 0.662 = conversion factor of m 3 CH 4 to kg CH 4 EPA, 2002
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Species Total Kjeld. N, kg/d VS, kg/d Max. CH 4 Bo, m 3 CH 4 /kg VS Dairy cow0.449.30*0.24 Dairy heifer0.317.770.17 Feedlot cattle0.305.440.33 Beef cow0.336.200.17 Market swine*0.425.400.48 Breeding swine0.242.600.48 Hens0.8310.80.39 Broilers1.1015.00.36 From Table L-2, EPA, 2002, *CO #s US-EPA Manure GHG inventory assumptions, 2002 (N &VS/1000 kg animal mass)
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Methane Conversion Factor Based on Van’t Hoff-Arrhenius equation f = exp[E(T 2 –T 1 )/RT 1 T 2 ] f = portion of VS available for CH 4 production T 1 = 303.16 K T 2 = weighted ambient temp (K) for each state E = activation energy (15,175 cal/mol) R = ideal gas constant (1.987 cal/K mol) EPA, 2002; Safley & Westerman, 1990
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Manure methane in 2002 EPA, 2004 Total 40 Tg CO 2 eq
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Manure N2O, CO2eq (USDA 04) Total = 77 Tg/yr
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All Mitigation Approaches Must: be based on a comprehensive, life cycle analysis that assesses emissions of all greenhouse gases. (NCCTI, 2001)
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CH 4 Mitigation (Mgt strategies) Eliminate anaerobic lagoons or capture CH 4 Eliminate stocker phase ~ direct to feedlot Maximize grain feeding – trade-offs with N 2 O Dilution of maintenance Faster gain or more milk/cow Hormone treatment use bST or implants
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Biogas from Livestock Waste Prior failures: 140 farm sys in 70’s (< 20%) Renewed interest: 50 now in use, 60 plan Cost $400 - $1200/cow, brk even 5 – 15c/kWh GHG savings: 6 MT/cow ?Synergisms? Odor, NH3- PM2.5, dust, health, acid rain, smog, etc.
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US Biogas Plants, USDA 04
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Methane Mitigation Research Immunization (Baker, Aust) Methane oxidizers (UK) H+ acceptors Nitrate (Japan) Fumaric acid (UK, Japan) Medium chain Fatty Acids (Switz)
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CH 4 Mitigation (Mgt strategies cont.) Select cows with low maintenance req. Increase forage digestibility Intensive Grazing Plant genetic select/modification ? Fat cows if fed ad libitum Tradeoff excess N (>20%CP, req~11%) Ammoniation of forage – trade-off with N 2 O MCFA – trade-off enteric, manure
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Diet %CP, Manure Sys vs N 2 O (Kulling,et. 01 J Ag Sci 137:235) Lactating Cows, 30.9 kg/d, 3 protein levels, +bypass Methionine 12.5 15 17.5% 3 Manure management systems Liquid manure in slurry (Slurry) Farmyard manure, liquid urine (FYM-US) Deep liter + 12 kg straw (DLM-Straw)
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Dairy % diet CP vs Emissions (Kulling 01, J Ag Sci 137:235)
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Manure System vs Emissions (Kulling 01)
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Manure vs. Synthetic N 250 kg N-Manure Stores 350 kg C Fuel (0) N 2 O-C 655 kg Net emissions 305 kg CE (1100 kg CO 2 eq) 250 kg N-Synthetic Stores 150 kg C Fuel 296 kg C N 2 O-C 655 kg Net emissions 801 kg CE (2900 CO 2 eq)
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80 - 51 - 118 Direct-IG 95 - 58 - 41 Direct 14.2 GHG/BW sold, % base 0 $ /T GHG 529 Net GHG, T/herd 1997 Base Abatement Strategies on Beef GHG Emissions & Profit
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Conclusions Manure Mgt? Anaerobic; N 2 O, CH 4 Covered lagoons? Efficient manure use Need good emission estimates
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Conclusions GHG abatement strategies should consider emissions of all GHG’s Reductions in feed/product central thrust Dilution of maintenance Reductions in excess N Soil C can add modest offsets to livestock
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