New Zealand's dairy sector aims to significantly reduce greenhouse gas (GHG) emissions, with targets to decrease methane emissions by 24-47% and maintain levels of nitrous oxide and carbon dioxide by 2050. Key mitigation strategies include enhancing animal production efficiency, integrating trees on farms, and utilizing low-emission feeds, alongside regulatory frameworks to manage nitrogen leaching. The focus on immediate GHG reduction practices reflects New Zealand's commitment to sustainability and environmental stewardship in agriculture.

1. New Zealand dairy sector greenhouse
gas emissions: current and future
reductions
Stewart Ledgard
AgResearch, New Zealand

2. New Zealand is world’s largest
exporter of dairy products
• Cows outdoors all year
• Perennial grass/clover pastures
• Over 80% feed from grazing pastures
• Average  15% feed brought-in

3. Outline of talk
1. New Zealand’s GHG reduction targets
2. Current dairy GHG emissions
3. GHG mitigation practices – current and
future
4. Current environmental mitigation focus

4. 2%
Other
44 %
Carbon dioxide
(CO2)
43%
Methane
(CH4)
11%
Nitrous Oxide
(N2O)
Other Energy
Transport
Agriculture Other Energy
Transport
Agriculture
New Zealand Emissions (%) Typical developed country (%)
11 40 49 9 80 11
New Zealand’s GHG emission profile:

5. New Zealand’s domestic GHG reduction target
Reduce gross
CH4
emissions by
24-47%
by 2050

6. New Zealand’s domestic GHG reduction target
Reduce net
N2O & CO2
emissions
0%
by 2050

7. New Zealand’s Emissions Trading Scheme
- Cost on C emissions, including agriculture
- Delayed for agriculture provided:
- All dairy farms have used a tool to benchmark their GHG
emissions by 2022
- They have a farm plan with GHG reduction options defined
- After 2025, they will be charged for their GHG emissions

8. National
GHG
inventory
On-farm
accounting
Carbon
footprint
GHG accounting & Carbon footprinting

9. Enteric Methane
Manure Methane
N2O from animals
N2O - other
Fuel
Electricity
Fertiliser production
Pesticide
Refrigerant
Replacements
Other Brought-in feed Top 4 contributors:
1. Enteric methane produced
in the rumen 67%
2. N2O from animals’ urine
and faeces 11%
3. Brought-in feed 10%
4. Fertiliser production 5%
GHG sources for NZ average dairy farm

10. New Zealand’s environmental emissions reduction

11. Carbon footprint of different feeds in NZ
*
*
*
*
* After allocation of GHG to main products
*Palm kernel expeller

12. Summary of GHG mitigation options
Discovery or Proof of concept
Available >5 years
Pilot studies
Available 2-5 years
Best practice
Available now
CH4 inhibitors/vaccines
Low GHG cows Low GHG sheep
Higher breeding value cows
+ lower stocking rate
Reduce replacement rate
Plants or pasture mixes with
low GHG traits
Low GHG feed options e.g.
Plantain, Fodder beet
Improve feed quality (ME)
Replace N fertiliser with
low-N feed
Alternative nitrification inhibitors? Urease inhibitors
Stand cows off pasture when
wet soils

13. 0
0.2
0.4
0.6
0.8
1
1.2
Intensive
housing
Low-C feed Base Low-C feed No N fertiliser Strategic cow
housing
Carbon
footprint
of milk
(kg CO2 eq
per kg FPCM)
CH4
N2O
CO2
------------------ New Zealand--------------------
Source:
Ledgard S F, Wei S, Wang X, Falconer S, Zhang N, Zhang X and Ma L 2019.
Nitrogen and carbon footprints of dairy farm systems in China and New
Zealand, as influenced by productivity, feed sources and mitigations.
Agricultural Water Management 213: 155-163
Carbon footprint of milk: Effects of some GHG mitigation options

14. 0
0.2
0.4
0.6
0.8
1
1.2
Intensive
housing
Low-C feed Base Low-C feed No N fertiliser Strategic cow
housing
Carbon
footprint
of milk
(kg CO2 eq
per kg FPCM)
CH4
N2O
CO2
------------------ New Zealand----------------------------China----------
Source:
Ledgard S F, Wei S, Wang X, Falconer S, Zhang N, Zhang X and Ma L 2019.
Nitrogen and carbon footprints of dairy farm systems in China and New
Zealand, as influenced by productivity, feed sources and mitigations.
Agricultural Water Management 213: 155-163
Carbon footprint of milk: Effects of some GHG mitigation options

15. Potential to reduce absolute agricultural emissions
Mitigation options applicable to dairy, beef and sheep farms
Existing
practices
Emerging
practices
Novel/new
practices
Emission reductions shown are relative to MPI business as usual emission projections for agriculture.
*
*
novel plants

16. Current environmental mitigation:
- driven by regulation reducing nitrogen leaching to
waterways, as calculated using the OVERSEER model:
- Management to increase pasture quality & animal efficiency
- Limits on nitrogen fertiliser use
- Using only low-N supplementary feeds

17. Summary:
• NZ dairying relies on low-cost unsubsidised year-round
grazing of perennial pastures
• Water quality regulations mean farmers are used to a
tool to meet N leaching limits – this will extend to GHGs
• Large GHG reduction targets will be achieved via a cost
on farm GHG emissions
Key mitigations will include:
- increased animal production efficiency
- increased nitrogen efficiency
- integrating trees on farm
- future options of methane inhibitor/vaccine
& low-emission feeds