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