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

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

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

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:

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

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

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

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

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

New Zealand’s environmental emissions reduction

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

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

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

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

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

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

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