farming systems to minimise gfg emissions: interactions and tradeoffs moving from paddocks to whole...
DESCRIPTION
Presentation from the WCCA 2011 conference in Brisbane, Australia.TRANSCRIPT
Farming systems to minimise GHG emissions: interactions and tradeoffs moving from paddocks to whole farms
Robyn Dynes
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
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
NZ GHG EMISSIONS 2007
Source: http://www.mfe.govt.nz/publications/climate/nz-2020-emissions-target/html/index.html
CHALLENGES AND OPPORTUNITIES-LAND-USE CHANGE
Potential
Feed :6 - 9 t DM/ha
ANIMALS:12 ewes +lambs/ha
IRRIGATION + FERTILISER
Source:www.siddc.org.nz
Feed:22 t DM/ha
Animals:4.2 cows/ha
0
50
100
150
200
250
300
350
400
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Fe
rtil
ise
r n
itro
ge
n u
se
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
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
N excess- urine patch, 500-1000 kg N /ha, source of most leaching and gaseous losses
N deficient- pasture N removed to the urine patch, soil OM and legumes supply N
leaching
gaseouslosses
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?
516
128
397
230
0
100
200
300
400
500
600
Urea + Urine (Autumn)
Urea + Urine (Autumn) + DCD
Urea + Urine (Spring)Urea + Urine (Spring) + DCD
Nit
rate
-N leach
ed
(kg
N /
ha .
yr)
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)
Large reduction in
leaching
Smaller reduction in
leaching
DCD TO CONTROL N LEACHING (?)
? ? ? ? ? ? ? ? ? ? ? ?
Year
0 5 10 15 20
% r
ed
uctio
n in
N le
ach
ing
0
20
40
60
80
patch-level experiments
Paddock level (modelled)
paddock-level (inferred from the patch experiments)
HILL COUNTRY SHEEP + BEEF : KING COUNTRY
800ha• breeding ewes• breeding cows• friesian bulls • trading cattle
GHG Emissions EFSt CO2-e/ha kg
CO2-e/kgCWE
$/ha
Current 4.91 14.3 313
+ Breeding ewes- Breeding cows
4.98 14.4 339
GHG Emissions EFSt CO2-e/ha kg
CO2-e/kgCWE
$/ha
Current 4.91 14.3 313
+ Breeding ewes- Breeding cows
4.98 14.4 339
GHG Emissions EFS
t CO2-e/ha kg CO2-e/kgCWE $/ha
Current 4.91 14.3 313
+ Breeding ewes- Breeding cows 4.98 14.4 339
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
Short term Medium term Long termReduce animal numbers1
Manipulate diet
Increase productivity per animal2
Rumen modifiers
Plants with low CH4 yield
Targeted manipulation of rumen ecosystem1
Breed animals with low CH4 yield1
ROUTES FOR GHG MITIGATIONShort term Medium term Long termReduce animal numbers1
Manipulate dietCattle winter management Soil managementType, quantity & timing of N fertiliser applicationsNitrification inhibitors1
Nitrification inhibitors1
Improved plant germplasm
Increase efficiency of N utilisation by ruminants1
Targeted manipulation of soil microbial processes1
Thank you
ROUTES FOR CH4 MITIGATION
Short term Medium term Long termReduce animal numbers1
Manipulate diet
Increase productivity per animal2
Rumen modifiers
Plants with low CH4 yield
Targeted manipulation of rumen ecosystem1
Breed animals with low CH4 yield1
1 Options with high mitigation potential 2 Reduces CH4/kg product, increases emission/animal
100 150 200 250 300 350 4006
7
8
9
10
11
12
13
14
15
Series1
Inte
nsity
of
emis
sion
s kg
CO
2-e/
kgC
WE
EFS $/ha
• opportunity with risk from climate and market
Methane (CH4) Nitrous Oxide (N2O)
Combined
Whole-Farm emissions from 700 ha(tonnes CO2-e)
2,384 1,055 3,439
Per Hectare Emissions(tonnes CO2-e per ha)
3.405 1.508 4.913
Emission intensity (kg CO2-e per kg of meat & fibre) 9.9 4.4 14.3
[1] Calculated using Overseer® ver. 5.4.3.0[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.
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
Methane (CH4) Nitrous Oxide (N2O)
Combined
Whole-Farm emissions from 700 ha(tonnes CO2-e)
2,384 1,055 3,439
Per Hectare Emissions(tonnes CO2-e per ha)
3.405 1.508 4.913
Emission intensity (kg CO2-e per kg of meat & fibre) 9.9 4.4 14.3
[1] Calculated using Overseer® ver. 5.4.3.0[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.
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
Methane (CH4) Nitrous Oxide (N2O) Combined
Whole-Farm emissions (tonnes CO2-e) NA NA NA
Per hectare emissions(tonnes CO2-e per ha)
7.5 4.6 13.5
Emission intensity (kg CO2-e per kg of Milk Solids) 9.9
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
2000 2200 2400 2600 2800 3000 32006
7
8
9
10
11
12
13
14
EFS $/ha
Inte
nsi
ty o
f em
issi
ons
kg C
O2-e
/kg
MS
Current
1990
More ewes-l
ess co
ws
More tr
ading c
attle
Summer fa
llow 3
3.5
4
4.5
5
5.5
6
4.91
5.68
4.98
5.33
4.41
Tota
l GH
G e
mis
sion
s t
CO
2-e/
ha
+ ewes- cows
+ trade cattle
Intensification increases total GHG production
Intensification increases total GHG production
Current
1990
More ewes-l
ess co
ws
More tr
ading c
attle
Summer fa
llow 5
7
9
11
13
15
17
19
14.3
17.8
14.4 14.5
12.9
Series1
+ ewes- cows
+ trade cattle
Inte
nsi
ty o
f em
issi
ons
kg C
O2-e
/kg
CW
E
• opportunity depends on current efficiency
Current 1990 More ewes-less cows
More trading cattle
Summer fallow 0
50
100
150
200
250
300
350
400
313
0
339
373
225
EF
S $
/ha
+ ewes- cows
+ trade cattle
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
Current 50% less N fert Hi BW low SR Hi BW low SR + DCD
10
10.5
11
11.5
12
12.5
13
13.5
13.1
11.3
12.7 12.6
Tota
l GH
G e
mis
sion
s t
CO
2-e/
ha
Current 50% less N fert Hi BW low SR Hi BW low SR + DCD
10
10.5
11
11.5
12
12.5
13
13.5
13.1
11.3
12.7 12.6
Tota
l GH
G e
mis
sion
s t
CO
2-e/
ha
Current 50% less N fert Hi BW low SR Hi BW low SR + DCD
8.4
8.6
8.8
9
9.2
9.4
9.6
9.8
10 9.9
9.3
9.6
9
Inte
nsi
ty o
f em
issi
ons
kg C
O2-e
/kg
MS
Current 50% less N fert Hi BW low SR Hi BW low SR + DCD
0
500
1000
1500
2000
2500
3000
3500
2759
2432
3023 3047
EF
S $
/ha
• can change both intensity and total emissions• depends on current GHG emission efficiency
Win-Win??
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