soil carbon and emission trading scheme mike beare nziahs forum (22 aug. 2012)

Soil Carbon and Emission Trading Scheme

Mike Beare

NZIAHS Forum (22 Aug. 2012)

The New Zealand Institute for Plant & Food Research Limited

Why do we have an Emission Trading Scheme?

Under the Kyoto Protocol, NZ agreed to reduce its GHG emissions back to 1990 levels by 2012 or pay for any excess.

Government chose the ETS as least-cost way of putting a price on emissions and creating an incentive for all of us – especially businesses and consumers – to change behavior.

ETS moves the cost of emissions onto those who cause them. Creates a market around reducing emissions.

28 other countries have an ETS (incl. Australian & US states).

Creates incentive to reduce emissions, invest in clean technology and renewable power generation and store C (e.g. planting trees).

ETS was reviewed in 2011 to assess how it is working and what our trading partners are doing about climate change.


What is included under ETS and When? What sectors are included under the ETS

• Forestry – entered Jan 2008 • Energy, Industry & Transport – entered July 2010• Agriculture – soon!

Proposed obligations under Agriculture

• participants initially meat & dairy processors, fertiliser manufacturers & importers, egg producers & live animal exporters.

• obligation to surrender NZUs for agricultural emission activities.

• Govt may move point of obligation to farm level in future, subject to practical issues, ability to verify emissions & enforce compliance.

• Agriculture emissions refers to non-CO2 GHG emissions from agricultural production – includes CH4 from livestock (~ 2/3), and N2O from animal excreta and use of N fertiliser (~ 1/3). Excludes soil C.

• Reporting was to begin Jan 2012, full obligations by Jan 2015.

• Recently, Govt deferred the start date to surrender obligations for biological emissions from agriculture – pending a review in 2015.


CH4

CH4

2010 Agric. emissions CH4 = 6.3 Mt CO2-Ce N2O = 2.7 Mt CO2-Ce

NZ Soil C stock = 2562 Mt C

What are the losses and gains?How do they impact on NZ’s net emissions?

z

Where do soils feature in the Global C Cycle ?Carbon (C) units:

1 t C = 1 Mg C

1 Gg C = 1000 t C

1 Mt C = 1000 Gg C

1 Pg C = 1000 Mt C


Why are we interested in Soil C?

Soil C – product of organic matter input from plants and animal excreta and organic matter decomposition.

These have important implications for the global C balance.

Agricultural soil C is not currently included in the ETS but is included in international GHG accounting protocols.

Global basis – total soil C pool is large (small changes could be important).

There is growing international interest in soil C as a source and sink for atmospheric CO2.

We don’t know how (i.e. point of obligation) or if soil C will be traded in the future and when.

Soil C is also linked to many important ecosystem services.

Supply of plant available nutrients, filtering, soil structure, biodiversity.


How do we measure Soil Carbon?Important considerations

Sample depth» Chemical fertility testing (0-15 cm samples), not adequate for soil C» Sampling to a fixed depth and known volume is essential» International C accounting/trading based on 0–30 cm» NZ data based on different depths of sampling, different protocols » Need for a standard, universally accepted protocol for NZ

Number of samples» SOM and C can be very spatially variable» Large number of samples required (15-25 for avg paddock)» Composite sample OK, but separate samples better

Corrections for soil bulk density are important

Comparing C in equivalent masses of soil is best


What is equivalent mass and why is it important?


What are implications of different methods?

Soil C content based 0-15 cm samples

Pasture Cropping (ploughed 20 cm)

Depth (cm)

BDg / cm3 C (%)

t C / ha

BDg / cm3 C (%)

t C / ha

0 - 7.5 1.20 3.2 28.8 1.10 2.1 17.3

7.5 - 15 1.30 2.4 23.4 1.15 2.2 19.0

Total (Avg)

(2.8) 52.2 (2.1) 36.3

C Loss -15.9


Determining the C content of soils(based on 0-25 cm samples)


Depth (cm)

BDg / cm3 C (%)

t C / ha

BDg / cm3 C (%)

t C / ha

0 - 7.5 1.20 3.2 28.8 1.10 2.1 17.3

7.5 - 15 1.30 2.4 23.4 1.15 2.2 19.0

15 - 25 1.35 1.8 24.3 1.35 2.6 35.1

Total (Avg)

(2.3) 76.5 (2.1) 71.4

C Loss - 5.1


Determining the C content of soils(based on equivalent soil mass)


Depth (cm)

BDg / cm3 C (%)

t C / ha

BDg / cm3 C (%)

t C / ha

0 - 7.5 1.20 3.2 28.8 1.10 2.1 17.3

900 825

7.5 - 15 1.30 2.4 23.4 1.15 2.2 19.0

975 863

15 - 25 1.35 1.8 24.3 1.35 2.6 35.1

1350 1350

Total 3225 76.5 3038 71.4

Equiv. mass

3225 76.5 3225 74.7

C loss - 1.8

Values in red are t soil / ha (i.e. the mass of soil at each depth)


Soil C stocks differ across land uses

Cropland - annual

Cropland - perennial

Grassland - high prod

Grassland - low prod

Grassland - + woody biomass

Natural forest

Post-1989 fo

rest

Pre-1990 planted forests

Wetlands

Soi

l C S

tock

s (t

C h

a-1 ,

0-3

0 cm

)

0

20

40

60

80

100

120

Jones et al. 2012


Soil C stocks differ across major soil orders

Allophanic

BrownGley

Granular

Melanic

OrganicPallic

Podzol

PumiceRecent

Ultic

Soi

l C S

tock

s (t

C h

a-1 ,

0-3

0 cm

)

0

50

100

150

200

250

Jones et al. 2012


NZ’s total soil C stocks by land use and change in soil C stocks due to land use change (1990-2010)

Source: NZ Greenhouse Gas Inventory 1990-2010 (Ministry for the Environment)Excludes data for wetlands, settlements and “other” land.

Land use Land area (ha)

Soil C stocks (Mt C)

1990-2010∆ soil C (Mt C)

Forest

Natural forest 8,084,403 749 0

Pre-1990 planted forest 1,441,894 134 - 2.44

Post-1989 forest 593,821 55 - 5.37

Grassland

High producing 5,795,395 679 + 2.49

Low producing 7,674,138 810 - 0.30

With woody material 1,134,031 105 - 0.82

Cropland

Annual 334,865 20 - 1.90

Perennial 102,901 10 - 0.68


Soils respond differently to changes in land use or management

Land use

LT Pasture STP/STA LT Arable

Soi

l Org

anic

car

bon

(t h

a-1 )

40

45

50

55

60

65

Brown (n = 67)Gley (n = 23)Pallic (n = 114)

- 5.3 t C/ha

- 13.6 t C/ha

- 10.5 t C/ha

Lawrence-Smith et al 2006


Are we losing or gaining soil C on our pastoral lands?

Land form Land use 0-30 cm 0-90 cm

n Avg. ∆C n Avg. ∆C

Flatland Drystock 27 -0.14 (0.15) 22 -0.31 (0.27)

Flatland Dairy 29 -0.73 (0.16) 25 -1.21 (0.25)

NI hill Drystock 15 0.52 (0.18) 12 1.00 (0.37)

SI tussock Drystock 12 0.00 (0.13) 3 -0.35 (0.08)

Change in total soil C (t C ha-1 yr-1) under different pastoral land uses

Dairy Sheep/beef Bull/beef

Soi

l C S

tock

s (t

C h

a-1 ,

0-3

0 cm

)

0

20

40

60

80

100

120

140

n = 169 n = 88 n = 18

Schipper et al. 2010

Losses of soil C are also associated with release of mineral N that contributes to higher N2O emission under international accounting rules.

Lawrence-Smith & Beare 2012


Soil Carbon Sequestration

Black/Biochar C

•Biomass pyrolysis•Soil amendments

Deep Placement•Deep roots•Bioturbation•Recalcitrant compounds

Lifting Prod’n on Degraded

Soils• INM

•Irrigation ?•Increase crop

cover (min fallow)

Increasing C Input into Soil•Residue mgt & reduced tillage

•Drip sub irrigation•N management

•Biosolids

Lal & Follett 2009 SSSAJ Spec Publication 57

Opportunities to sequester (store) soil C and reduce losses

NZAGRC Research to increase soil C storage:

•stocks & upper limits of soil C storage •mechanisms of soil C stabilisation. •use of Biochar to sequester C•introduce deep burrowing earthworms to bury soil C•mixed pasture swards with deep rooted species

Other Research•Rates of soil C loss under LUC•Reduced tillage systems to conserve soil C (cropping & pasture renewal)•Irrigation effects on soil C stocks•Measurement and modelling of functional pools


CHALLENGES TO SOC SEQUESTRATION

Competing uses

of biomass

Fodder

Fuel

Industrial material

Construction material

Human

dimensions

Land tenure

Mindset

Gender issues

Farming system

Immediate vs. long-term

needs

Non-availability

of input

Specific mechanisms

Herbicides

Fertilisers

Improved varieties

Weak institutions

Soil factors

Texture

Clay minerals

Drainage

Topography

Climate

parameters

Temperature

Precipitation

ET

Rainfall distribution

Pedosphere/

atmosphere interaction

The Human Dimension Biophysical Factors

Lal & Follett 2009 SSSAJ Spec Publication 57


Ecosystem Services &

Soil Organic Carbon

Sequestration

Erosion Control

•Reduction in nonpoint source pollution

•Decline in sedimentation

Desertification Control

•Decline in susceptibility to desertification

•Land saving technologies

Increase in Biodiversity

•Soil fauna and flora

•Avoiding deforestation

Purification of Water

•Bioremediation

•Denaturing of pollutants

improvement in soil structure

storehouse of germplasm

soil as a biomembrane

Soil/ecosystem restoration

Lal & Follett 2009

… and there are many other benefits of soil C


Conclusions

NZ Soil C stock is relatively large compared to annual emissions of CH4 and N2O from agriculture.

Annual changes in soil C appear small, but what are implications of changes in land uses?

Are we losing or gaining soil C from intensification of existing land uses?

How we measure soil C stocks and changes is important (Paddock & Nationally)

Soil C stocks differ substantially by land use, soil class and climate

Potential to increase soil C storage appears to be small (more research needed)

Given our stocks of C are high, risk of soil C losses is biggest concern.

• Pastoral land and selected soils (e.g. peats, Allophanics etc)

Beyond soil C accounting, important that we account for the full range of ecosystem services provided by soil C.

Thank you for your attention

soil carbon and emission trading scheme mike beare nziahs forum (22 aug. 2012)

Documents

agricultural soil c

store c

mt c slide

c e nz soil c stock

global c balance

carbon c units

global c cycle

soil carbon