Carbon Sequestration in Temperate

Grasslands

The Signpost Series

‘Pointing the way to a low emissions agriculture’

Donal O’Brien

Teagasc,

Crops, Environment & Land Use Centre

Johnstown Castle, Co. Wexford

Outline

EU Green Deal and Climate Action

Carbon Sequestration

Land use & management

Climate Neutral Livestock Farming

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Europe’s Green Deal

A roadmap for sustainable

growth

• Circular Economy:

» “Give back more than it takes away”

- President of the EU Commission

• Restore habitats and biodiversity

• Climate neutral continent

» Net zero greenhouse gas (GHG)

emissions by 2050

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©Fotolia, petovarga

Agriculture and The Green Deal

“Farm to fork” strategy

• Fair return for producers

• Affordable food

• 25% of total farmland organic

Carbon farming initiative

• Curbing climate change

• Payments for increasing C sequestration and GHG reduction

» CAP and/or carbon markets

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Ireland’s Climate Action Plan

Consistent with EU climate neutrality vision

Aims to meet Irish GHG targets for EU effort sharing regulation – 2020 to 2030

• Requires concerted action from all sectors

• Does not compromise food production ambitions

Carbon sequestration allowed reduce ~6% (2.7 Mt CO2/yr) of Irish emissions

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ESR* targets & GHG projections

0

5

10

15

20

25

30

35

40

45

50

2021 2022 2023 2024 2025 2026 2027 2028 2029 2030

Mt

CO

2 e

qu

ivale

nts

National GHG emissions

Agriculture

Other

Transport

AEA_NF*

6

*ESR = EU Effort sharing regulation

*AEA_NF = Annual emission allowance no flexibilities

ESR* targets & GHG projections

0

5

10

15

20

25

30

35

40

45

50

2021 2022 2023 2024 2025 2026 2027 2028 2029 2030

Mt

CO

2 e

qu

ivale

nts

National GHG emissions

Agriculture

Other

Transport

AEA_WF*

7

*ESR = EU Effort sharing regulation

*AEA_WF = Annual emission allowance with flexibilities

Teagasc – GHG mitigation strategy

1. Reduce agricultural greenhouse gas

emissions

2. Displace fossil fuel and improve

energy efficiency

3. Enhance carbon sequestration

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The Carbon Cycle

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Photosynthesis & Assimilation

Soil organic carbon (matter)

Heterotrophic

Respiration

CO2

+

H2O

CO2

Decomposition

CO2

Hydrocarbon (fossil fuel)

CO2

Active carbon

Passive carbon

CO2 + CH4

CO2

Organic

C

Autotrophic

Respiration

CO2

Dissolved carbon

What is Carbon Sequestration?

Carbon sequestration is a biological process part of the carbon cycle

The main steps of the process are:

1. Vegetation absorbs CO2 via photosynthesis

2. Absorbed CO2 is assimilated into organic carbon

3. Organic carbon (C) is respired or transferred to soil or wood for storage

Factors that regulate C sequestration

Climate

Type of soil

Land use

Land management

12

Measurement

Quantifying C Sequestration is Complicated!

Modelling

Mapping

Measuring Soil Organic C (SOC)

Most organic C is in top soil (30cm)

• Labile – easy to breakdown

C content of subsoil is low & stable

• Less turnover & exposure to atmosphere

Deeper soil sampling required for C

• 50cm to 1 metre

C Sequestration verified by long-term sampling

Labile SOC

1-2 years

C/N ratio: 20-30

Recalcitrant SOC

500-5000 years

C/N ratio: 7-10

Organic

C

100cm

30cm

Measuring C Fluxes

Flux tower quantify net C exchange

in agro-ecosystems: Daily & Annually

Measure continuously (every sec)

• Wind speed and CO2 mixing ratio

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Measuring C Fluxes

Flux tower quantify net C exchange in agro-ecosystems: Daily & Annually

Measure continuously (every sec)

• Wind speed and CO2 mixing ratio

Sensitive to effect of weather and management on C

• Indirectly estimates herbage growth

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Dry summer

Net CO2 exchange in agro-ecosystem

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-1500

-1000

-500

0

500

1000

1500

-8

-6

-4

-2

0

2

4

6

8

Cu

mu

lati

ve C

Flu

x (

g C

m-2

)

Da

ily C

Flu

x (

g C

m-2

d-1

)

ΣNEE = -374 g C m-2

Photosynthesis

Respiration

Lanigan et al. 2014

Net C Exchange & Net C Storage

-10

-5

0

5

10

15

20

1 2 3 4 5 6

Net

Carb

on

, t

CO

2/h

a p

er

year

Year

Grassland - Johnstown Castle

Exchange Storage

Positive net exchange =

CO2 uptake

Net C storage includes:

• C inputs

» Organic fertilizer

• C removals

» Cutting and grazing

• C losses

» Erosion, wildfire etc..

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Lanigan et al. 2014

Modelling C Sequestration

Soil C levels modelled for unmeasured sites

Models developed from climate, soil C and flux records

Ecosse, DayCent, PaSIM & RothC valid soil C models

• Relatively accurate

• Struggle to predict grass growth

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Model applications Monitor C storage at small & large scale

• From sites to farms, regions, nation

Simulate C sequestration by good farming practices

• Correct soil pH, P and K (0.8 t CO2/ha per year)

• Spread slurry on tillage land (1.1 t CO2/ha per year)

Project impact of climate change on soil C

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Balancing Irish agricultural GHG’s

Bovine herd - Principal driver of agricultural GHG emissions

Irish cattle producers amongst the most GHG efficient in the world

• EU Commission

Further gains in efficiency challenging

• Enhance C sequestration to balance GHG’s

» Climate neutral

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Balancing Irish agricultural GHG’s

Annual GHG’s from

cattle farms

simulated with life

cycle assessment

• On-farm sources

» Cattle, manure, fertilizer,

fuel, soils…

• Off-farm sources

» Electricity, concentrate,

fertilizer, fuel….

Dairy* Beef*

-40%

-20%

0%

20%

40%

60%

80%

100%

GH

G b

ala

nce i

n C

O2 e

qu

ivale

nt

Carbon dioxide Nitrous oxide Methane

21

*Average producer in 2017

1 kg Methane = 25 kg CO2; 1 kg Nitrous oxide = 298 kg CO2

(9 t CO2e/ha) (4 t CO2e/ha)

Suckler beef farms – GHG balance

11.9

10.5

15

0

2

4

6

8

10

12

14

16

NA - 1.4 LU/ha HS - 2.2 LU/ha LS - 0.4 LU/ha

kg

CO

2 e

qu

iv.

per

kg

LW

G

Gross GHG

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Suckler beef farms – GHG balance

11.9

10.5

15

5.5

1.6

12.9

0

2

4

6

8

10

12

14

16

NA - 1.4 LU/ha HS - 2.2 LU/ha LS - 0.4 LU/ha

kg

CO

2 e

qu

iv.

per

kg

LW

G

Gross GHG C Sequestration

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Suckler beef farms – GHG balance

11.9

10.5

15

5.5

1.6

12.9

6.4

8.9

2.1

0

2

4

6

8

10

12

14

16

NA - 1.4 LU/ha HS - 2.2 LU/ha LS - 0.4 LU/ha

kg

CO

2 e

qu

iv.

per

kg

LW

G

Gross GHG C Sequestration "Gross-Net" GHG

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4.2 1.9 2.3

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Gross GHGemission

CSequestrationsoils & hedges

Gross netGHG emission

Me

tric

t C

O2 e

qu

iva

len

t/h

ecta

re

(± 1.0) (± 1.8) (± 3.0)

25

Low GHG Irish Beef Farm

Afforest 1/4 hectare

4.2 1.9 2.3 2.3

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Gross GHGemission

CSequestrationsoils & hedges

Gross netGHG emission

Additional CSequestration

Net net GHGemission

Me

tric

t C

O2 e

qu

iva

len

t/h

ecta

re

(± 1.0) (± 1.8) (± 3.0) (± 0.4)

26

Climate Neutral Irish Beef Farm

Afforest 1/4 hectare

9

1.9

7.1 7.1

0

1

2

3

4

5

6

7

8

9

10

Gross GHGemission

CSequestrationsoils & hedges

Gross netGHG emission

Additional CSequestration

Net net GHGemission

Me

tric

t C

O2 e

qu

iva

len

t/h

ecta

re

(± 2.0)

(± 1.8)

(± 4.0) (± 1.0)

27

Climate Neutral Irish Dairy Farm

Afforest 2/3 hectare

Summary

C sequestration supports the delivery of climate neutral livestock farming

• Reduces GHG’s in grass-based livestock farms

Quantity of GHG’s reduced by C sequestration in grassland variable & uncertain (-1.9 to 5.5 t CO2/ha)

• Aim to monitor larger number of grassland sites

The distance to climate neutrality target is lower on extensive grass-based livestock farms

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Summary

Achieving climate neutrality is difficult on high output efficient grass-based livestock farm

Demo events key to transferring C efficient farming practices

Afforestation & low emission technologies likely to be needed to achieve long-term GHG targets

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3-NOP Seaweed,

Asparagposis spp.

© Getty Images © DSM

Forestry

Helpful Links

EU Farm to fork strategy: https://ec.europa.eu/info/strategy/priorities-2019-2024/european-green-deal/actions-being-taken-eu/farm-fork_en

Climate Action Plan 2019: https://www.dccae.gov.ie/en-ie/climate-action/publications/Pages/Climate-Action-Plan.aspx

Teagasc Daily Online: https://www.teagasc.ie/publications/2020/enhancing-soil-carbon-sequestration-to-contribute-to-carbon-neutrality-on-irish-farms.php

NEFERTITI: https://nefertiti-h2020.eu/

CIRCASA: https://www.circasa-project.eu/

Redmond, 2019. Grassland and carbon sequestration. Teagasc Moorepark 19’ booklet: https://www.teagasc.ie/media/website/publications/2019/Grassland-and-carbon-sequestration.pdf

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Thank you for listening

Questions?

Acknowledgements

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