The Science of Farm Emissions


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Professor Richard Eckart is Australia's most prominent scientific mind in the greenhouse gas in agriculture field. He specialises in methane and nitrous oxide measurement and amelioration. The presentation and data herein is for information only and can only be reproduced with permission of the author.

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The Science of Farm Emissions

  1. 1. The Science of Farm Emissions Methane & Nitrous Oxide Richard Eckard Associate Professor, The University of Melbourne & Department of Primary Industries
  2. 2. Sectoral Greenhouse Gas Emissions Australia 2006 DCC 2008
  3. 3. Agricultural Greenhouse Gas Emissions 2006 <ul><li>Agriculture </li></ul><ul><ul><li>58% of all methane </li></ul></ul><ul><ul><li>81% of all nitrous oxide </li></ul></ul><ul><li>Enteric Methane </li></ul><ul><ul><li>10.8% of National emissions </li></ul></ul><ul><li>Nitrous Oxide from soils </li></ul><ul><ul><li>2.8% of National emissions </li></ul></ul>DCC 2008 Methane Nitrous oxide
  4. 4. Methane and Nitrous Oxide sources
  5. 5. Typical Farm Emissions Dairy 3 - 7 t CO2e/cow 4 – 45 t CO2e/ha Beef 2 t CO2e/steer 2 – 3 t CO2e/ha Grains 0.2 - 1 t CO2e/ha
  6. 6. Carbon Pollution Reduction Scheme <ul><li>Agricultural emissions </li></ul><ul><ul><li>Start by 2015, decision by 2013 </li></ul></ul><ul><ul><li>If not in CPRS, other policies will be considered </li></ul></ul><ul><ul><ul><li>16% of national account cannot be ignored </li></ul></ul></ul><ul><ul><ul><li>Other polices could provide less flexibility </li></ul></ul></ul><ul><li>Either way </li></ul><ul><ul><li>We will face some incentive to reduce emissions on-farm </li></ul></ul>
  7. 7. Enteric Methane Emissions <ul><li>Produced by methanogens in rumen </li></ul><ul><ul><li>Anaerobic microbes of the Archaea Domain </li></ul></ul><ul><ul><ul><li>Use H 2 to reduce CO 2 to form CH 4 </li></ul></ul></ul><ul><ul><li>>90% breathed or eructated </li></ul></ul><ul><li>Shorter lifetime in atmosphere & high GWP </li></ul><ul><ul><li>21 x CO 2 </li></ul></ul><ul><li>A significant loss of energy </li></ul><ul><ul><li>6 to 10% of energy intake lost as methane </li></ul></ul>Eckard 2006 Animal Class Methane (kg/year) Equivalent grazing days of energy lost per animal Potential km driven in 6-cylinder LPG car Mature ewe 10 to 13 41 to 53 90 to 116 Beef steer 50 to 90 32 to 57 450 to 800 Dairy cow 90 to 146 24 to 38 800 to 1350
  8. 8. Methane Measurement Methane from Individual animals in the field using SF 6 Tracer Permeation tubes Evacuated Yolk Grainger et al. 2007
  9. 9. Methane Measurement Precise Methane from Individual Animals - Chambers/Calorimeters Grainger et al. 2007
  10. 10. Wind Reflector Reflector Laser Methane Measurement Methane from herds in the field - Open Path Laser & FTIR Griffiths et al. 2007
  11. 12. Methane Abatement Options Animal Management <ul><li>Reducing unproductive animal numbers </li></ul><ul><ul><li>Extended lactation in dairy </li></ul></ul><ul><ul><li>Earlier finishing of beef </li></ul></ul><ul><ul><ul><li>10-15% less methane </li></ul></ul></ul>Grainger et al. 2008 Wilson & Edwards 2008
  12. 13. Methane Abatement Options Animal Breeding <ul><li>Heritability </li></ul><ul><ul><li>Methanogenesis (15%) </li></ul></ul><ul><ul><ul><li>Conflicts with breeding objectives? </li></ul></ul></ul><ul><ul><li>Net Feed Intake (13%) </li></ul></ul><ul><ul><ul><li>Compatible with efficiency gains </li></ul></ul></ul><ul><ul><ul><ul><li>Angus, Vasse, WA </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Dairy cattle, Ellinbank & NZ </li></ul></ul></ul></ul>Clark et al. 2005; Grainger et al. 2008; Hegarty et al. 2007; Waghorn et al 2006
  13. 14. Methane Abatement Options Dietary Supplements <ul><li>Dietary Oils (5-25%) </li></ul>Beauchemin et al. 2007 Grainger et al. 2007 1% added fat = 6% less methane
  14. 15. Methane Abatement Options Dietary Supplements <ul><li>Tannins (10-25%) </li></ul><ul><ul><li>Less </li></ul></ul><ul><ul><ul><li>Methane loss </li></ul></ul></ul><ul><ul><ul><li>Urinary N loss </li></ul></ul></ul><ul><ul><li>More </li></ul></ul><ul><ul><ul><li>Dung N </li></ul></ul></ul><ul><ul><ul><li>Soil retention </li></ul></ul></ul><ul><li>Sources of Tannin </li></ul><ul><ul><li>Acacia spp </li></ul></ul><ul><ul><li>Commercial beverage additives </li></ul></ul><ul><ul><li>High tannin legumes </li></ul></ul><ul><ul><li>Plant breeding </li></ul></ul>Waghorn et al 2006 Grainger et al. 2008
  15. 16. Methane Abatement Options Dietary Supplements <ul><li>Monensin (0-10%) </li></ul><ul><li>Yeasts (0-5%) </li></ul><ul><li>Enzymes (9-28%) </li></ul><ul><li>Nitrates, TCM, BCM </li></ul><ul><li>etc </li></ul>
  16. 17. Methane Abatement Options Longer-Term Options (5 – 20 yrs) <ul><li>Biological control </li></ul><ul><ul><li>Vaccination </li></ul></ul><ul><ul><li>Bacteriophages, Bacteriocins, </li></ul></ul><ul><ul><li>Archaeal Viruses, Fungal Pathogens </li></ul></ul><ul><li>Acetogenesis </li></ul><ul><ul><li>Kangaroo, wallaby </li></ul></ul><ul><ul><ul><li>Faster gut rate of passage = acetogens </li></ul></ul></ul><ul><ul><ul><li>Same function as methanogens </li></ul></ul></ul><ul><ul><ul><ul><li>But produce acetate, not methane </li></ul></ul></ul></ul>
  17. 18. Nitrous Oxide <ul><li>Long residence time in atmosphere </li></ul><ul><li>High GWP </li></ul><ul><ul><li>310 x CO 2 </li></ul></ul><ul><li>Denitrification </li></ul><ul><ul><li>Warm, water-logged soils </li></ul></ul><ul><ul><li>Excess N in soil </li></ul></ul><ul><li>Inefficient use of nitrogen </li></ul><ul><ul><li>>60% N inputs lost from grazing systems </li></ul></ul>
  18. 20. N 2 O Measurement Automatic Chambers & Micromet Systems Automatic Chambers Micromet system
  19. 21. Temporal Variability in Daily N 2 O Irrigated dairy pastures Phillips et al. 2006
  20. 22. Rate of N on N 2 O Emissions Irrigated Cotton Grace et al. 2007
  21. 23. Season and N Source on N 2 O Emissions Dryland Pastures Eckard et al. 2002
  22. 24. Nitrification Inhibitors on N 2 O Emissions Pastures <ul><li>50% less N 2 O for 50 days mid-spring </li></ul><ul><li>25% less N 2 O for 25 days in mid-summer </li></ul>Kelly et al;. 2008
  23. 25. Land Conversion impacts on N 2 O Emissions Wheat/Sheep Rotations, Hamilton <ul><li>-0.5 to 183 g N 2 O-N/ha/d </li></ul><ul><ul><li>1.6 kg N 2 O-N/ha in one event </li></ul></ul>Kelly & Graham 2008 Year 1 Year 2
  24. 26. Refining N 2 O Emission Factors Low Rainfall Cropping Cunderdin Rutherglen Horsham EF (% of N) 0.02 % <0.01 % 0.14 % Annual Loss (kg N 2 O-N/ha) 0.09 - 0.11 0.17 – 0.24 0.42 – 0.5 Barton et al. 2007 Barker-Reid et al. 2007 Officer et al. 2008
  25. 27. Managing Nitrous Oxide from Nitrogen <ul><li>Fertiliser management </li></ul><ul><ul><li>Rate, Timing, Source and Placement </li></ul></ul><ul><li>Soil management </li></ul><ul><ul><li>Soil structure </li></ul></ul><ul><ul><li>Stubble retention </li></ul></ul><ul><li>Fertiliser formulation </li></ul><ul><ul><li>Controlled Release </li></ul></ul><ul><ul><li>Inhibitors </li></ul></ul><ul><li>Urine </li></ul><ul><ul><li>Tannins </li></ul></ul><ul><ul><li>Protein : Energy ratios </li></ul></ul><ul><ul><li>Spray inhibitors </li></ul></ul>
  26. 28. Key Challenges <ul><li>Point of Obligation for CPRS </li></ul><ul><ul><li>Up-stream and Down-Stream </li></ul></ul><ul><ul><ul><li>Fertiliser company </li></ul></ul></ul><ul><ul><ul><ul><li>Coat all fertilisers at a cost </li></ul></ul></ul></ul><ul><ul><ul><li>Processor, abattoir </li></ul></ul></ul><ul><ul><ul><li>No incentive for on-farm action </li></ul></ul></ul><ul><ul><ul><ul><li>But lower cost </li></ul></ul></ul></ul><ul><ul><li>On-Farm </li></ul></ul><ul><ul><ul><li>Higher Transaction Costs </li></ul></ul></ul><ul><ul><ul><ul><li>130,000 extra reporting </li></ul></ul></ul></ul><ul><ul><li>No agreed method for reliable & cost-effective reporting </li></ul></ul>
  27. 29. Key Challenges <ul><li>No low cost ‘measurement’ methods </li></ul><ul><li>Need agreed modelling method </li></ul><ul><ul><li>Method must allow incentive through differentiation </li></ul></ul><ul><ul><ul><li>Is a cow a cow? </li></ul></ul></ul><ul><ul><li>Inventory vs on-farm models </li></ul></ul><ul><ul><ul><li>Industries have developed DSS Tools </li></ul></ul></ul><ul><ul><ul><ul><li>Dairy, Beef, Sheep, Grains, Wine calculators </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cotton (QUT), FarmGas (AFI) and DGAS (Dairy) </li></ul></ul></ul></ul><ul><ul><ul><li>Industries have developed models & Tools </li></ul></ul></ul><ul><ul><ul><ul><li>Grains – APSIM </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Dairy – DairyMod </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Beef/Sheep – GrassGro / SGS </li></ul></ul></ul></ul>
  28. 30. In Conclusion <ul><li>Farmers will face emissions restrictions in future </li></ul><ul><ul><li>BUT HOW? </li></ul></ul><ul><ul><li>Less options for extensive systems </li></ul></ul><ul><ul><li>Research may take 5 to 20 years still </li></ul></ul><ul><li>Should we be imposing new costs? </li></ul><ul><ul><li>Global economic crisis </li></ul></ul><ul><ul><li>Predicted food shortages </li></ul></ul><ul><ul><li>Drought & climate change </li></ul></ul><ul><li>World Food Price Increases </li></ul><ul><li>BUT - Clearly we cannot farm in the future as we have in the past </li></ul><ul><li>Need on-farm technologies that deliver </li></ul><ul><ul><li>Abatement of methane and nitrous oxide </li></ul></ul><ul><ul><li>PLUS improving profitability & resilience </li></ul></ul><ul><ul><li>Meeting world demand & in a changing climate </li></ul></ul>
  29. 31.
  30. 32. Whole Farm Systems Analysis Needed <ul><li>Inhibitor sprays </li></ul><ul><ul><li>61-91% less nitrous oxide from urine </li></ul></ul><ul><ul><ul><li>Whole farm abatement = 8.4 and 12.5% </li></ul></ul></ul><ul><ul><li>But 25% more pasture growth </li></ul></ul><ul><ul><ul><li>25% more cows = 11.5 and 7.6% MORE CO2e </li></ul></ul></ul><ul><ul><ul><ul><li>OR </li></ul></ul></ul></ul><ul><ul><ul><li>25% less N fert = 12.0 and 16.2% LESS CO2e </li></ul></ul></ul><ul><li>Dietary Oils </li></ul><ul><ul><li>4% more oil = 22.4% less CH4 </li></ul></ul><ul><ul><ul><li>= 16% less total farm emissions </li></ul></ul></ul><ul><li>Additivity of options </li></ul><ul><ul><li>Not all additive </li></ul></ul>