Soil carbon

Diane Allen, DSITI: Carbon workshop Charleville 15/12/2015

Productivity benefits, methods explained, applicability in South West Queensland and implications

Soil and the carbon cycle

Soil carbon and productivity benefits

Measuring and modelling soil carbon

Soil carbon and the ERF – applicability and implications for south west Qld

Where do I find more info? Who can help?

Source: http://genomicscience.energy.gov

Raymond (2005) Nature 436, 469-470

Raymond (2005) Nature 436, 469-470

Kaiser et al. 2015, Nature comms

As some of the soil microbial community produce enzymes to break down organic

matter, C and N is lost in the process

Soil organic carbon – a part of soil organic matter

Organic matter makes up less than 10% of the soils mass but has a critical role in the physical, chemical and biological function of soils.

About 58% of the mass of organic matter exists as carbon. The content of carbon can be measured to estimate soil organic matter.

Source: WA Government

SOC: a function of the inputs and outputs

Courtesy Ram Dalal, DSITI

Plants & animals

Decomposableorganic residues

Soil biomass

Humus

Soil surface

CO2

CO2

CO2

Fresh residues

(labile) < 10%

Living organisms and roots

(labile) < 5%

Particulate organic C

(labile) 10 – 50%

Humus

(decadal) 33 – 50%

Char or black carbon/resistant

(inert) 1 – 30%

Adapted from Skjemstad & Baldock, 2000

Total carbon or a sum of its parts

Soil health

Nutrient cycling

Carbon sequestration

Tota

l C

arb

on

Hum

us,

part

icula

te, re

sis

tant

carb

on “

pools

”

What are the productivity benefits of managing SOC?

Sources: Text (United Nations Environment Program); Photos (Soil Science Society Australia)

Productivity benefits of soil organic carbon

Improving awareness of soil physical, biological and chemical conditions to maximise pasture production & business capacity to respond to change in weather, climate

Source: UNEP Year Book 2012

Productivity benefits of soil organic carbon

Physical – minimising sodic and erosive soil loss, soil sealing, salinity; maximising infiltration rates, water holding capacity, PAWC

Biological and chemical - enhancing native and sown pasture production; nutrient availability, supply and turnover

Response and Resilience – climate, weather and management interaction

Australia has 14 soil types (Soil Orders), reflecting the arid, strongly-weathered nature of the Australian continent

western Qld:Cracking clay soils – VertosolsMassive earths – KandosolsTexture contrast soils – SodosolsDeep sandy soils - Tenosols

Charleville

Kandosols Vertosols Sodosols Tenosols

0 1 0 1 0 1 2 3 0 2 4 6

Soil 1 Soil 2 Soil 4Soil 3

0

50

100

150

200

So

il D

ep

th (

cm

)

Soil organic carbon content (% by weight)

2

What affects soil organic carbon levels?

Climate: Temperature, rainfall, Vapour Pressure DeficitVegetation typeSoil texture and type of clay and oxides (Parent Material)TopographyTimeThe above 5 factors govern the (natural) soil formation

Management: Land use practices and change Interaction of management and time

Images: Teresa Eyre and Queensland Government

Viscarra Rossel et al. 2014, Global Change Biology

Time

Equilibrium level

(Pasture/Forestry)

(cropping)

SO

C % Land use or

management change

New equilibrium level

Cropping and soil carbon, Queensland

Dalal and Meyer Aust. J. Soil. R, 1986

Sanderman and Baldock, S.R.Letters, 2010

Reducing SOC loss - Building SOC

Crop management• Soil fertility enhancement, better rotation, irrigation, fallow elimination

Conservation tillage• Stubble retention, reduced tillage, no-tillage

Pasture management • Fertilizer management, grazing management, earthworm introduction,

irrigation, improved grass species, legume introduction, sown pasture

Organic amendments• Animal manure, biosolids

Land conversion• Degraded cropland to pasture, bioenergy crop, agroforestry, biochar, land

clearing methods

Soil (and carbon) loss - erosion

Stream Bank

Gully

Tunnel

Land slip Wind

Scald

Rill and sheet

Australian Government workstream: Soil Carbon

• Developing consistent methodology for quantification of soil carbon stocks

• Soil type x land management across climate gradient – cropping and grazing land management

• Special Edition of International Journal Soil Research 2013, 7-8, 561-780.

Soil Carbon Research Program (SCaRP) 2009-2012 (Program leader Jeff Baldock, CSIRO)

National Soil Carbon Program (NSCP) 2012-2017 (Program leader Ram Dalal, DSITI)

• Part of DAFF ‘Filling the Research Gap’ program

• Research outcomes underpin development of new abatement methodologies that land managers can use to participate in the Carbon Farming Initiative (CFI).

• Round 1: 15 soil projects, 11 Project Delivery Organisations

• Linkage with DAFF ‘Action on the Ground’ program which trial and demonstrate a range of on-farm technologies and practices

Measurement approach: Australia example

Source: Commonwealth of Australia, 2015

Sampling design and approach: Australia example

Challenge for getting reliable estimates of vegetation and soil carbon -representative sampling of the landscape

Do different scales of sampling require different sampling approaches?

Which sampling designs assess SOC (i) across the paddock, (ii) over different time scales, (iii) both?

Sampling design and approach: Australia example

Sanderman et al. 2011 Orton et al. 2015

Sampling design and approach: Australia example

Fresh residues

(labile) < 10%

Living organisms and roots

(labile) < 5%

Particulate organic C

(labile) 10 – 50%

Humus

(decadal) 33 – 50%

Char or black carbon/resistant

(inert) 1 – 30%

Adapted from Skjemstad & Baldock, 2000

Total carbon or a sum of its parts

Soil health

Nutrient cycling

Carbon sequestration

Tota

l C

arb

on

Hum

us,

part

icula

te, re

sis

tant

carb

on “

pools

”

Total SOC and C fractions – sieving & combustion

Total SOC: sample usually air-dried and sieved to 2mm particle sizePOC and HOC fractions: undertaken by wet-sieving, sorting organic matter on the basis of mesh size. POC (2mm - 53µm), HOC (<53µm). Sample then dried for analysis of carbon content

Prediction using infra-red spectroscopy

Baldock et al 2013 Soil Research

Relies on statistical relationships between infra-red (IR) soil spectra and results from soil C measurements

Grazing lands management, northern Australia and SOC

130 E 135 E 140 E 145 E 150 E

25

S20

S15

S10

S

Longitude

Latitu

de

1

2

3

4

5

6

7

Kidman Springs

8

9

10

11

12

13

14

15*

Toorak

16*

Wambiana

17

BRISBANE

DARWIN

1. Quantify the effect of rainfall, soil type, pasture systems and pasture management on soil organic carbon (SOC) stocks in grazing lands;

2. Estimate the soil carbon pools of total carbon stocks in grazing lands

3. Provide datasets for carbon models to account for pasture management practices under variable rainfall and soil type conditions.

Allen et al. 2013, Soil Research

130 E 135 E 140 E 145 E 150 E

25

S20

S15

S10

S

Longitude

Latitu

de

1

2

3

4

5

6

7

Kidman Springs

8

9

10

11

12

13

14

15*

Toorak

16*

Wambiana

17

BRISBANE

DARWIN

• 26 year trial, different pasture grazing• Soil C stock (0-0.5 m)

largest under 20% pasture utilisation and smallest under 80% pasture utilisation.

• Variability increased with depth.• soil C stocks correlated with an annual

measure of total standing dry matter (correlated with NDVI).

Pasture grazing - Sheep

Pringle el et al. 2013, Geoderma

130 E 135 E 140 E 145 E 150 E

25

S20

S15

S10

S

Longitude

Latitu

de

1

2

3

4

5

6

7

Kidman Springs

8

9

10

11

12

13

14

15*

Toorak

16*

Wambiana

17

BRISBANE

DARWIN

• Trial commenced in 1997 comparing different types of cattle grazing intensity (no grazing, light – moderate, heavy)

• 10 sites ~ 1,000,000m2 each• Soil C stocks showed a strong

interaction between grazing pressure x soil type

Grazing: stocking intensity – Beef cattle

Allen et al 2009; Pringle el et al. 2011

Full Carbon Accounting Model (FullCAM)

Understanding carbon changes using carbon models

Soil sub model

Years

Soil

org

anic

car

bo

n

(g C

kg-1

soil)

0 10 20 30 40 50 60 70

TOC

Land use change

Initiate land use

0

5

10

15

20

25

30

3315 43

HumC

ROCPOC

18 y 10 y

less humus C

more POC

Courtesy Jeff Baldock, CSIRO

Understanding carbon changes over time using carbon models

NSCP projects that have application for FullCAM

Soil carbon increase through rangeland restoration by facilitating native forest regrowth

Environmental plantings for soil carbon sequestration on farms

Native perennial vegetation: building stable soil carbon and farm resilience

Soil carbon benefits through reforestation in sub-tropical and tropical

Quantifying temporal variability of soil carbon

Understanding the influence of grazing pressure changes on soil organic carbon in the semi-arid rangelands of western NSW

The fate of aboveground carbon inputs: a key process that is poorly understood

Soil Methods Under ERF agriculture and vegetation sectors^

^as at 01/12/2015

Agriculture

•Beef cattle herd management •Destruction of methane from piggeries using engineered biodigesters *•Destruction of methane generated from dairy manure in covered anaerobic ponds *•Destruction of methane generated from manure in piggeries 1.1 *•Estimating sequestration of carbon in soil using default values•Fertiliser use efficiency in irrigated cotton•Reducing greenhouse gas emissions in beef cattle through feeding nitrate containing supplements *•Reducing greenhouse gas emissions in milking cows through feeding dietary additives *•Sequestering carbon in soils in grazing systems *

*methods transitioned from CFI to ERF on 01/07/2015

Vegetationmanagement

•Avoided clearing of native regrowth•Avoided Deforestation 1.1•Designated Verified Carbon Standard projects•Human-induced regeneration of a permanent even-aged native forest 1.1 *•Measurement based methods for new farm forestry plantations *•Native forest from managed regrowth *•Reforestation and Afforestation 2.0•Reforestation by Environmental or Mallee Plantings - FullCAM *•Savanna fire management

Defines the carbon estimation area (CEAs) and eligible project activities:• Increasing biomass yields (sustainable intensification) on crop or pasture areas by

optimising fertiliser, applying lime, introducing irrigation, or pasture renovation .• Converting land under crops to pasture (conversion to pasture).• Retaining crop residue in field rather than burning or baling it (stubble retention).

Provides CFI mapping tool and nominated permanence of 25 or 100y

Monitoring of soil and emission sources required - CEAs must also be monitored every six months to ensure that vegetation ground cover is maintained.

Specifies requirements for undertaking projects, reporting and auditing

Source: Commonwealth of Australia, 2015

Sequestering Carbon in Soils in Grazing Systems Determination (transitioned from CFI to ERF) - direct measurement method

• Activities : crop to permanent pasture, rejuvenating pasture, changing grazing • Resources provided re how and when to sample, where to analyse

Variable landscapes Sampling design Sampling in the field

Soil carbon in northern grazing lands: reflections from NSCP

• From 100y to 25y timeframes

• teasing apart climate and management; soil C management within whole GHG balance; financial forecasting at individual and aggregated scales; – streamlining determination eligibility

• If moving towards FullCAM approach, what are ‘missing gaps’ in rangelands for SOC? Including: biomass inputs, litter decomposition and turnover rates, SOC in relation to land type, quantifying grazing intensity and duration (BoS Management classes)

• Benefit of research: spatially-referenced data , link to existing and long-term data, ongoing monitoring

https://www.environment.gov.au/climate-change/emissions-reduction-fund/methods/method-development

More info? www.qld.gov.au

Qld Globe: farming, planning, soils, vegetation, inland waters

https://data.qld.gov.au/maps-geospatial/qld-globe

Soils globe – soil surveys and reports

https://data.qld.gov.au/maps-geospatial/qld-globe

Site observationSoil morphology describedLab test results e.g. pH, electrical conductivityChloride, organic Carbon, Total N, K, P

https://www.qld.gov.au/environment/land/soil/

international-year-of-soil-2015-activities

http://www.fao.org/soils-2015/

http://www.soilscienceaustralia.com.au/