Presentation from the WCCA 2011 conference in Brisbane, Australia.

1. Farming systems to minimise GHG
emissions: interactions and tradeoffs
moving from paddocks to whole farms
Robyn Dynes

2. LAND-BASED INDUSTRIES
• Export earnings
• $25b
• Employment
• 156 000 people in Ag, forestry & Fishing
• 75 000 in food & beverage manufacture ?
• food exports to world
• NZ feeds 17 million people
[Source: INFOS series http://www.stats.govt.nz/products-and-services/infos/ AgResearch
analysis. http://www.stats.govt.nz/analytical-reports/labour-market-statistics-2008.htm
Food export: AgResearch analysis from: MAF SONZAF (2008), ibid year to 31
March 2008

3. WHY IS NEW ZEALAND SO INTERESTED IN
AGRICULTURAL GHG?
Agriculture responsible for:
• 48% of NZ emissions
• 52% of NZ total merchandise exports
NZ produces:
• 40% of world’s tradable dairy products
• 66% of tradable lamb products
Developed & developing country problem

4. NZ GHG EMISSIONS 2007
Source: http://www.mfe.govt.nz/publications/climate/nz-2020-emissions-target/html/index.html

5. CHALLENGES AND OPPORTUNITIES-
LAND-USE CHANGE
Potential
Feed :
6 - 9 t DM/ha
Animals:
12 ewes +lambs/ha

6. IRRIGATION + FERTILISER
400
350
Fertiliser nitrogen use
300
Feed: 250
200
22 t DM/ha 150
100
50
0
Animals: 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
4.2 cows/ha
Source:www.siddc.org.nz

7. THE CHALLENGE OF AGRICULTURAL
NON-CO2 EMISSIONS
CH4 & N2O
Emissions vary over time –hourly, daily, weekly, monthly & annually
Emissions vary in space – patch, paddock, farm & region
Multiple influences on emissions – environmental, physical, biological
Complex problem and not all processes influencing emissions are fully
understood
Mitigating emissions from grazing animals particularly challenging

8. NITROUS OXIDE MANAGEMENT IN NZ
PASTORAL AGRICULTURE
is the management of urine patches - not fertiliser
• N in a urine patch - 30 x typical fertiliser application

9. N deficient
- pasture N removed to the urine patch,
soil OM and legumes supply N
gaseous
losses
N excess
- urine patch, 500-1000 kg N
/ha, source of most leaching
and gaseous losses
leaching

10. NITRIFICATION INHIBITORS TO
CONTROL N LEACHING (?)
Dicyandiamide (DCD) inhibits nitrification and so N remains as NH4+,
adsorbed to the soil, 60-70% less leaching
more N retained in the system → more growth
→ more grazing → more urine patches → potential leaching
→ more litter return to soil → higher soil OM → less N deficient between
patches → more growth → …
→ higher soil C:N → less immobilisation → more pot. leaching
what are the likely long term effects?

11. Total annual NO3--N leached from lysimeters containing a lismore soil with urea applied
at 200 kg N / ha and urine applied at 1000 kg N / ha (Di & Cameron, 2002)
600
516
500
Nitrate-N leached (kg N / ha . yr)
397 Smaller
400
reduction in
Large leaching
300 reduction in
leaching 230
200
128
100
0
Urea + Urine Urea + Urine Urea + Urine (Spring)Urea + Urine (Spring)
(Autumn) (Autumn) + DCD + DCD

12. DCD TO CONTROL N LEACHING (?)
0
Paddock level
% reduction in N leaching
20 (modelled)
40
paddock-level (inferred from the patch experiments)
60
? ? ? ? ? ? ? ? ? ? ? ?
patch-level experiments
80
0 5 10 15 20
Year

13. HILL COUNTRY SHEEP + BEEF : KING COUNTRY
• breeding ewes
• breeding cows 800ha
• friesian bulls
• trading cattle

14. GHG Emissions EFS
t CO2-e/ha kg CO2- $/ha
e/kgCWE
Current 4.91 14.3 313
+ Breeding ewes 4.98 14.4 339
- Breeding cows

15. GHG Emissions EFS
t CO2-e/ha kg CO2- $/ha
e/kgCWE
Current 4.91 14.3 313
+ Breeding ewes 4.98 14.4 339
- Breeding cows

16. GHG Emissions EFS
t CO2-e/ha kg CO2-e/kgCWE $/ha
Current 4.91 14.3 313
+ Breeding ewes
4.98 14.4 339
- Breeding cows

17. SUMMARY
• Some experimental data available at some scales
• Conceptually scaling in time and space has the potential to
affect outcomes at a systems level.
• Nitrification inhibitors: biophysical example of issues with scaling
• Farming enterprise changes– if considered independently do not
match the systems behaviour

18. ROUTES FOR GHG MITIGATION
Short term Medium term Long term
Reduce animal numbers1 Nitrification inhibitors1 Increase efficiency of N
Manipulate diet utilisation by ruminants1
Improved plant germplasm
Cattle winter management Targeted manipulation of
soil microbial processes1
Soil management
Type, quantity & timing of
N fertiliser applications
Nitrification inhibitors1
Short term Medium term Long term
Reduce animal numbers1 Rumen modifiers Targeted manipulation of
rumen ecosystem1
Manipulate diet Plants with low CH4 yield
Breed animals with low
Increase productivity per CH4 yield1
animal2

19. Thank you

20. ROUTES FOR CH4 MITIGATION
Short term Medium term Long term
Reduce animal Rumen modifiers Targeted manipulation
numbers1 of rumen ecosystem1
Plants with low CH4 yield
Manipulate diet Breed animals with low
CH4 yield1
Increase productivity per
animal2
1 Options with high mitigation potential
2 Reduces CH4/kg product, increases emission/animal

22. • opportunity with risk from climate and market
20
Intensity of emissions kg CO2-e/kgCWE
18
16
14
12
10
8
6
100 150 200 250 300 350 400
EFS $/ha
Series1

23. Methane (CH4) Nitrous Oxide Combined
(N2O)
Whole-Farm emissions from 700 ha 2,384 1,055 3,439
(tonnes CO2-e)
Per Hectare Emissions 3.405 1.508 4.913
(tonnes CO2-e per ha)
Emission intensity (kg CO2-e per kg of meat & fibre) 9.9 4.4 14.3
Calculated using Overseer® ver. 5.4.3.0
[1]
[2]
Meat & fibre production is expressed as carcass weight equivalents. All sheep meat and beef production is converted to carcass weight units. Scoured wool weight is
converted to carcass weight on a 1:1 basis.

24. Scenario Whole-Farm emissions from 700 ha Per Hectare Emissions Emission intensity
(tonnes CO2-e) (tonnes CO2-e per ha) (kg CO2-e per kg of meat &
fibre)
CH4 N2O Total
Baseline 2,384 1,055 3,439 4.91 14.3
Nitrification inhibitor 2,384 1,022 3,406 4.86 14.1
More ewes- less cows 2,472 967 3,439 4.91 14.4
Changing flock age structure 2,454 956 3,410 4.87 14.5
Replacing the breeding herd 2,683 1,048 3,731 5.33 14.5
Once-bred heifers 2,120 848 2,968 4.24 16.6
Deer breeding and finishing 2,326 921 3,247 4.64 17.7
Summer fallow 10% 2,218 867 3,085 4.41 12.9
Year-1990 performance based
on 450 ha pastoral 1,839 718 2,557 5.68 17.8

25. Methane (CH4) Nitrous Oxide Combined
(N2O)
Whole-Farm emissions from 700 ha 2,384 1,055 3,439
(tonnes CO2-e)
Per Hectare Emissions 3.405 1.508 4.913
(tonnes CO2-e per ha)
Emission intensity (kg CO2-e per kg of meat & fibre) 9.9 4.4 14.3
Calculated using Overseer® ver. 5.4.3.0
[1]
[2]
Meat & fibre production is expressed as carcass weight equivalents. All sheep meat and beef production is converted to carcass weight units. Scoured wool weight is
converted to carcass weight on a 1:1 basis.

26. Scenario Whole-Farm emissions from 700 ha Per Hectare Emissions Emission intensity
(tonnes CO2-e) (tonnes CO2-e per ha) (kg CO2-e per kg of meat &
fibre)
CH4 N2O Total
Baseline 2,384 1,055 3,439 4.91 14.3
Nitrification inhibitor 2,384 1,022 3,406 4.86 14.1
More ewes- less cows 2,472 967 3,439 4.91 14.4
Changing flock age structure 2,454 956 3,410 4.87 14.5
Replacing the breeding herd 2,683 1,048 3,731 5.33 14.5
Once-bred heifers 2,120 848 2,968 4.24 16.6
Deer breeding and finishing 2,326 921 3,247 4.64 17.7
Summer fallow 10% 2,218 867 3,085 4.41 12.9
Year-1990 performance based
on 450 ha pastoral 1,839 718 2,557 5.68 17.8

27. Methane (CH4) Nitrous Oxide (N2O) Combined
Whole-Farm emissions (tonnes CO2-e) NA NA NA
Per hectare emissions 7.5 4.6 13.5
(tonnes CO2-e per ha)
Emission intensity (kg CO2-e per kg of Milk Solids) 9.9

28. GHG CH4 N2O Emissions Emission cost Emission cost
N leaching emissions emissions emissions intensity no off-set 90% off-set
Scenario description kg N/ha t CO2 eq/ha t CO2 eq/ha t CO2 eq/ha * $/ha** $/ha**
Base 45 13.5 7.5 4.6 9.9 338 33.84
Half N 30 11.8 6.9 3.7 9.3 295 29.47
High BW cows, lower SR 42 13.0 7.1 4.4 9.4 326 32.57
Base + DCD 39 13.4 7.7 4.1 9.3 334 33.40
High BW cows, lower SR + DCD 38 12.9 7.4 4.0 8.8 323 32.32
* = kg CO2 equivalents / kg ms
** At $25/t CO2 -equivalents

29. Intensity of emissions kg CO2-e/kg MS
14
13
12
11
10
9
8
7
6
2000 2200 2400 2600 2800 3000 3200
EFS $/ha

30. Intensification increases total GHG production
6
5.68
Total GHG emissions t CO2-e/ha
5.5 5.33
4.91 4.98
5
4.5 4.41
4
3.5
3
Current 1990 + ewes + trade
More ewes- More trading Summer
- less cows
cows cattle
cattle fallow

31. Intensification increases total GHG production

33. • opportunity depends on current efficiency
Intensity of emissions kg CO2-e/kgCWE
19
17.8
17
15 14.3 14.4 14.5
12.9
13
11
9
7
5
Current 1990 + ewes + trade
More ewes- More trading Summer
- less cows
cows cattle
cattle fallow

34. 400
373
350 339
313
300
250
225
EFS $/ha
200
150
100
50
0
0
Current 1990 More ewes-less tradetrading Summer fallow
+ ewes + More cattle
cows
- cows cattle

35. Mid Canterbury Dairy Farm
• 3.8 cows/ha
• 0.7t/cow supplements bought-in
• 206 kg/ha N
• 344 KgMS/cow = 1320 kgMS/ha
• feed consumed = 15.6 t DM/ha

36. 13.5
13.1
13
Total GHG emissions t CO2-e/ha
12.7
12.6
12.5
12
11.5 11.3
11
10.5
10
Current 50% less N fert Hi BW low SR Hi BW low SR +
DCD

37. 13.5
13.1
13
Total GHG emissions t CO2-e/ha
12.7
12.6
12.5
12
11.5 11.3
11
10.5
10
Current 50% less N fert Hi BW low SR Hi BW low SR +
DCD

38. 10 9.9
Intensity of emissions kg CO2-e/kg MS
9.8
9.6
9.6
9.4 9.3
9.2
9
9
8.8
8.6
8.4
Current 50% less N fert Hi BW low SR Hi BW low SR +
DCD

39. 3500
3023 3047
3000 2759
2500 2432
EFS $/ha
2000
1500
1000
500
0
Current 50% less N fert Hi BW low SR Hi BW low SR +
DCD

40. Win-Win??
• can change both intensity and total emissions
• depends on current GHG emission efficiency
Sheep + Beef Dairy
• total pasture production • cow stocking rate
• seasonal pasture production • genetic merit
• feed utilisation • feed utilisation
• nutrients, temp, rainfall • imported feed
• Willingness and ability to change system