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A comparison of farm-scale models to
estimate greenhouse gas emissions
from dairy farms in Europe
The MACSUR Science confe...
Background
• Farm scale is essential when upscaling ruminant
livestock production
– significant flexibility in management
...
Models
• SFarMod
– optimised management
– emission factors
– portable
– 30+ years experience
• Dairywise
– optimised feed ...
Models
• FarmAC
– user inputs management
– emission factors (except dynamic soil model)
– portable
– 1 year of experience
...
Standard factorial scenarios
Warm x cool
climate
Sandy x clay
soil
Grass only x
grass & maize
Cool climate grazing 5 month...
RESULTS
Grass & maize
Grass only
Sand Clay
Cool Warm
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
SFarMod Dairywise FarmAC HolosNor
Dairy cows per ha
Differences in feed requiremen...
0
2
4
6
8
10
12
14
SFarMod Dairywise FarmAC HolosNor
Total farm GHG emissions (Mg CO2 e / ha)
Note – pre-chain/post-chain ...
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
SFarMod Dairywise FarmAC HolosNor
Emission intensity (kg CO2 e / kg ECM)
Cool clim...
0
1000
2000
3000
4000
5000
6000
7000
SFarMod Dairywise FarmAC HolosNor
Enteric methane emissions (kg CO2 e / ha)
FarmAC lo...
0
500
1000
1500
2000
2500
SFarMod Dairywise FarmAC HolosNor
Manure methane emissions (kg CO2 e / ha)
Dairywise imposes Net...
0
100
200
300
400
500
600
700
SFarMod Dairywise FarmAC HolosNor
Manure N2O emissions (kg CO2 e / ha)
Higher for cool clima...
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
SFarMod Dairywise FarmAC HolosNor
Field N2O emissions (kg CO2 e / ha)
D...
0
200
400
600
800
1000
1200
1400
1600
1800
SFarMod Dairywise FarmAC HolosNor
Total farm indirect GHG emissions
(kg CO2 e /...
0
20
40
60
80
100
120
140
160
SFarMod Dairywise FarmAC HolosNor
NO3 leaching (kg NO3-N / ha / year)
Large differences betw...
0
10
20
30
40
50
60
70
80
90
SFarMod Dairywise FarmAC HolosNor
NH3 emissions from field (kg NH3-N / ha / year)
Large diffe...
Conclusions (1)
• Total GHG emissions per kg milk and per ha
were similar for all models
– but this disguises some major d...
Conclusions (2)
• Assumptions concerning farm management
are important
– need for more empirical data and better
understan...
A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe
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A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe

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Title: A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe
Authors:
Nicholas Hutchings1 Daniel Sandars2, Şeyda Özkan3 Michel de Haan4

Affiliations:
1Dept. of Agroecology, Aarhus University, Blichers Allé 20, PO Box 50, 8830 Tjele, Denmark
2Institute for Environment, Health, Risk and Futures, School of Energy, Environment and Agrifood (SEEA), Cranfield University, Cranfield, Bedfordshire, MK43 0AL, United Kingdom
3Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, PO Box 5003, 1432 Ås, Norway
4Wageningen UR Livestock Research, PO Box 338, 6700 AH Wageningen, Netherlands


Email: Nick.Hutchings@agro.au.dk


Abstract: Farm-scale models quantify the cycling of nitrogen (N) and carbon (C) so are powerful tools for assessing the impact of management-related decisions on greenhouse gas (GHG) emissions, especially on dairy cattle farms, where the internal cycling is particularly important. Farm models range in focus (economic, environmental) and the detail with which they represent C and N cycling. We compared four models from this range in terms of on-farm production and emissions of GHGs, using standardized scenarios. The models compared were SFarMod, DairyWise, FarmAC and HolosNor. The scenarios compared were based on two soil types (sandy clay versus heavy clay), two roughage systems (grass only versus grass and maize), and two climate types (Eindhoven versus Santander). Standard farm characteristics were; area (50 ha), milk yield (7000 kg/head/year), fertiliser (275 kg N and 150 kg N/ha/year for grass and maize, respectively). Potential yields for grass 10t dry matter (DM)/ha/year in both areas, maize 14 t DM/ha/ year in Eindhoven and 18t DM/ha/ year in Santander. The import of animal feed and the export/import manure and forages was minimized. Similar total farm direct GHG emissions for all models disguised a variation between models in the contribution of the different on-farm sources. There were large differences between models in the predictions of indirect GHG emission from nitrate leaching. Results could be explained by differences between models in the assumptions made and detail with which underlying processes were represented. We conclude that the choice of an appropriate farm model is highly dependent upon the role it should play and the context within which it will operate, so the current diversity of farm models will continue into the future.

1. Presentation type preference: Oral

2. The session at which I would prefer to present:
Day 2 sessions
Live M Theme
Farm-scale modelling

Published in: Science
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A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe

  1. 1. A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe The MACSUR Science conference 8-10 April 2015 Reading University UK Nick Hutchings, Michel De Haan Şeyda Özkan, Daniel Sandars
  2. 2. Background • Farm scale is essential when upscaling ruminant livestock production – significant flexibility in management – substantial internal nutrient cycling • Farm models differ in: – Focus (production/economics/environment) – Purpose (supporting farmers/farm advisors, regulators) • How would these differences affect results if the models were used to simulate the same dairy cattle farms?
  3. 3. Models • SFarMod – optimised management – emission factors – portable – 30+ years experience • Dairywise – optimised feed supply – empirical emission factors – location-specific (Netherlands) – 10+ years of experience
  4. 4. Models • FarmAC – user inputs management – emission factors (except dynamic soil model) – portable – 1 year of experience • HolosNor – user inputs management – emission factors – Canadian model, adapted for Norway – 2-3 years of experience
  5. 5. Standard factorial scenarios Warm x cool climate Sandy x clay soil Grass only x grass & maize Cool climate grazing 5 months Warm climate grazing 10 months 16 hours/day grazing Minimum use of concentrates No manure import/export 600 kg LW & 7000 kg ECM/cow/yr Dairy cows + followers (1:1) Plant-available N: Grass 275 kg/ha/yr Maize 150 kg/ha/yr (Manure broadcast) For each scenario, adjust cow numbers to match feed supply
  6. 6. RESULTS
  7. 7. Grass & maize Grass only Sand Clay Cool Warm
  8. 8. 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 SFarMod Dairywise FarmAC HolosNor Dairy cows per ha Differences in feed requirement models For grass & maize - differences in area allocated to maize HolosNor uses FarmAC livestock numbers
  9. 9. 0 2 4 6 8 10 12 14 SFarMod Dairywise FarmAC HolosNor Total farm GHG emissions (Mg CO2 e / ha) Note – pre-chain/post-chain not simulated Grass only > grass & maize Little effect of soil type – true for most variables
  10. 10. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 SFarMod Dairywise FarmAC HolosNor Emission intensity (kg CO2 e / kg ECM) Cool climate > warm Grass only > grass & maize (except HolosNor)
  11. 11. 0 1000 2000 3000 4000 5000 6000 7000 SFarMod Dairywise FarmAC HolosNor Enteric methane emissions (kg CO2 e / ha) FarmAC low – feed requirement model predicts lower intake necessary to achieve 7000 litres milk/yr
  12. 12. 0 500 1000 1500 2000 2500 SFarMod Dairywise FarmAC HolosNor Manure methane emissions (kg CO2 e / ha) Dairywise imposes Netherlands manure regulations concerning manure storage Higher for cool climate (more manure produced in housing)
  13. 13. 0 100 200 300 400 500 600 700 SFarMod Dairywise FarmAC HolosNor Manure N2O emissions (kg CO2 e / ha) Higher for cool climate (more manure produced in housing) but relationship between models differs relative to methane
  14. 14. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 SFarMod Dairywise FarmAC HolosNor Field N2O emissions (kg CO2 e / ha) Differences between models in how they treat manure N and excretal N
  15. 15. 0 200 400 600 800 1000 1200 1400 1600 1800 SFarMod Dairywise FarmAC HolosNor Total farm indirect GHG emissions (kg CO2 e / ha) Indirect = nitrous oxide emission resulting from nitrate leaching and ammonia emission
  16. 16. 0 20 40 60 80 100 120 140 160 SFarMod Dairywise FarmAC HolosNor NO3 leaching (kg NO3-N / ha / year) Large differences between models Grass only > grass & maize Effect of soil type in some models
  17. 17. 0 10 20 30 40 50 60 70 80 90 SFarMod Dairywise FarmAC HolosNor NH3 emissions from field (kg NH3-N / ha / year) Large differences between models (different emission factors) Grass only > grass & maize
  18. 18. Conclusions (1) • Total GHG emissions per kg milk and per ha were similar for all models – but this disguises some major differences between models • Little effect of soil type • All models tended to predict lower emissions for the warm climate • More work necessary to understand the details of why models differ
  19. 19. Conclusions (2) • Assumptions concerning farm management are important – need for more empirical data and better understanding of processes • If used to prioritise mitigation measures, these models would give very different answers • It has been a useful learning exercise

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