1.
A comparison of greenhouse gas (GHG) emissions
from dairy farms by four systems models
with eight agro-climatic scenarios
Daniel Sandars ACB ALB, Research Fellow
Project 4 Technical Presentations, Camulodunum Speakers,
23 May 2016
Daniel Sandars, Nick Hutchings, Şeyda Özkan, Michel De Haan

2.
Acknowledgements
FACCE-JPI and National Funding Bodies

3.
The Four Models
• SFARMMOD, Cranfield University, UK
• DairyWise, Wageningen University,
The Netherlands
• FarmAC, Aarhus University, Denmark
• HolosNor, Norwegian University
of Life Sciences

4.
Eight (23)
Agro-climatic scenarios
Climate
Cool v. Warm
Netherlands v. N
Spain
Soil type
Light v. Heavy
Sand v. Clay
Cropping
Grass v. Grass and
Forage Maize

5.
Key Points
1. Overall the models are in good agreement
2. They vary in the detail
3. Experiences and Recommendations

6.
Carbon Footprint

7.
Total per kg Milk

8.
From the Cow’s body

9.
From Manure management

10.
From the Field and farm

11.
Discussion & experiences
• The scenarios only make small differences to the Total
• Farm-gate not Life-Cycle GHG emissions
– e.g. not the manufacture of fertilisers
• No new measurements
• Not all management factors can or were controlled
– e.g. area of maize, etc.
• Hard work
– assembling and interpreting data from novel regions
– Identifying assumptions and ambiguities between
models

12.
Recommendation
• Using all four models together “Ensemble
modelling”
– Robust average and spread of results
– Triangulation effect
– The best (and worst) of all models
– Need to be able to control more management
factors between models
– Need to understand the differences and improve
the models

13.
Key points
1. Good general agreement across models
2. The devil is in the ‘smaller’ details
3. Key carbon footprint is: Enteric CH4, Field
N2O and Manure CH4
4. Ensemble modelling offers the next step
beyond model comparison
5. Challenge the sixth sense when looking at
unfamiliar regions, models, and data.