1. How will the Soil Carbon Research Program and other research projects assist carbon trading? Jeff Baldock, Jon Sanderman and Lynne Macdonald (and many others) Carbon Farming Conference, Dubbo, NSW, 27-28 October 2010

2. Soil Carbon Research Program (SCaRP) Australian Government Department of Agriculture, Fisheries and Forestry

3. Introduction Reducing atmospheric CO 2 is important, an urgency to act does exist and soils do represent a potential sink Capturing additional carbon in Australian soils provides advantages to production systems beyond sequestration alone Potential approaches to carbon offset programs and what our science projects are doing to aid development The potential for carbon capture depends on an interaction between soil type, climate and management (past and current) A single solution for all Australian soils does not exist Solutions must be tuned to the location Some regions will have a higher potential than others

4. Potential approaches to soil carbon assessment for offset programs Measurement based (retrospective changes over time) Predicted changes (projections based on proposed management changes) Approaches may sit at a variety of positions between these two extremes Measurements taken at multiple points in time across the entire area of interest, analyse the trend through time No measurement - change in soil C based solely on evidence base of impact of practice Initial measurement + calibrated soil carbon model to estimate impacts of practice change Initial and final measurement with no assessment of inter-annual variation Confidence in the magnitude of soil carbon change decreases Value of carbon decreases or proportion of soil carbon placed in a buffer increases

5. Potential approaches to soil carbon assessment for offset programs Measurement based (retrospective changes over time) Predicted changes (projections based on proposed management changes) Approaches may sit at a variety of positions between these two extremes Measurements taken at multiple points in time across the entire area of interest, analyse the trend through time No measurement - change in soil C based solely on evidence base of impact of practice Initial measurement + calibrated soil carbon model to estimate impacts of practice change Initial and final measurement with no assessment of inter-annual variation Confidence in the magnitude of soil carbon change decreases Value of carbon decreases or proportion of soil carbon placed in a buffer increases

6. Measurements taken at multiple points in time (monitoring program) Time 0 Time 1 Time 2 Time 3 Time X y = 0.84x + 23 R² = 0.7436 0 10 20 30 40 50 60 0510152025 Soil organic carbon (Mg C/ha) Time (years) Sources of variation Management Climate Spatial Things to consider Consistent approach to sampling (depth, time of year, account for variations in bulk density) Sample according to management units and soil type Expensive (sampling and analysis) Confidence in soil carbon change is high Potential exists to place a high proportion of carbon change into an offsets program SCaRP Not a monitoring program – 3 year project 5% of field sites will be treated this way to offer future potential

7. What do we analyse and how? Total soil organic carbon versus soil carbon fractions For carbon sequestration purposes – total soil organic carbon If information regarding the vulnerability of soil carbon to future change is desired – soil carbon fractions Total organic carbon A variety of laboratory methods exist Dry combustion techniques are favoured Some labs report soil organic matter rather than carbon (SOM = 1.72 x SOC) Soil carbon fractions Particulate, humus and resistant (char) forms of organic carbon No commercial service available Currently time consuming and expensive SCaRP is examining the potential of MIR/PLS to provide a rapid/cost effective alternative

8. Relationship between predicted and measured values for SOC

9. Predicting the allocation of SOC to carbon fractions 0 2 4 6 8 10 12 14 16 01020 Measured MIR/PLS predicted POC (g C/kg soil) R 2 = 0.71 Janik et al. (2007) Aust J Soil Res 45:73 R 2 = 0.86 ROC (g C/kg soil) 0 2 4 6 8 10 12 051015 Measured MIR/PLS predicted SCARP program 1.Extension of testing to a wide range of soil types 2.Provision of calibration samples to labs across Australia 3.Assess the confidence associated with using MIR/PLS predictions in a carbon offsets modelling MIR/PLS analysis is providing a rapid and cost effective method of analysis for SOC and allocation to fractions

10. Potential approaches to soil carbon assessment for offset programs Measurement based (retrospective changes over time) Predicted changes (projections based on proposed management changes) Approaches may sit at a variety of positions between these two extremes Measurements taken at multiple points in time across the entire area of interest, analyse the trend through time No measurement - change in soil C defined on evidence base of impact of a defined practice Initial measurement + calibrated soil carbon model to estimate impacts of practice change Initial and final measurement with no assessment of inter-annual variation Confidence in the magnitude of soil carbon change decreases Value of carbon decreases or proportion of soil carbon placed in a buffer increases

11. Measurements taken at only two points in time Change in SOC 17 Mg C/ha or 0.84 Mg C/ha/y 2 nd sample taken after 8 years Change in SOC 4.5 Mg C/ha or 0.56 Mg C/ha/y 2 nd sample taken after 10 years Change in SOC 16 Mg C/ha or 1.6 Mg C/ha/y Things to consider Variability in factors other than management practice may be large (e.g. rainfall) Less confident in attributing any observed change in soil carbon solely to management The amount of carbon placed into an offsets program will require discounting (create a bigger buffer) SCaRP Developing measurement capability as described previously Soil sampling of this nature is not occurring

12. Potential approaches to soil carbon assessment for offset programs Measurement based (retrospective changes over time) Predicted changes (projections based on proposed management changes) Approaches may sit at a variety of positions between these two extremes Measurements taken at multiple points in time across the entire area of interest, analyse the trend through time No measurement - change in soil C defined on evidence base of impact of a defined practice Initial measurement + calibrated soil carbon model to estimate impacts of practice change Initial and final measurement with no assessment of inter-annual variation Confidence in the magnitude of soil carbon change decreases Value of carbon decreases or proportion of soil carbon placed in a buffer increases

13. Initial measurement + calibrated soil carbon model ModellingMeasurement + 1.All of the previous comments apply 2.Objectives of the measurements needs to be considered and an appropriate sampling plan put into place The spatial extent of subsequent modelling (single paddock/farm versus regions) Variations in management strategies being considered for implementation 1.Data inputs What is required and how they will be provided 2.Calibration of the model Climate Management etc

14. Measurement component – what is SCaRP doing? The extent of climate by soil type by management practice combinations across Australia is vast Each State project is focussing on specific regions and soil types Variations in management strategies are being handled either randomly or targeted to a series of predefined regimes Objective – collect and analyse soil samples from enough paddocks to build a specific assessments of current carbon stocks and composition on a region/soil/management basis

15. What is a Frequency Distribution Proportion of samples falling in each range Soil organic carbon (Mg C/ha) 20 µ = average σ = standard deviation 3040506070 Becomes a better representation of reality as sample numbers increase

16. Frequency distribution of soil organic carbon from Esperance WA samples 9.332.0 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0102030405060 Relative frequency Soil organic carbon (mg C kg -1 soil) 0-10 cm layer

17. Frequency distribution of soil organic carbon from Midnorth SA soil samples Relative frequency Soil organic carbon (mg C kg -1 soil) 0102030405060 0.00 0.02 0.04 0.06 0.08 0.10 0-10,10-20, and 20-30 cm layers 25 7

18. Defining differences between management practices Soil organic carbon (tC/ha) Frequency distribution The classical comparison of mean values uses a 95% confidence T2T2 µ2µ2 σ2σ2 n2n2 T1T1 µ1µ1 σ1σ1 n1n1 Confidence 0.01 0.05 0.10 0.25 0.50 10.2 6.3 2.1 1.1 0.5  SOC Relationship between level of confidence and the size of the change in soil carbon Management practice 1 Management practice 2

19. Modelling component – what are SCaRP and other projects doing? Collecting archived and current field samples from long term field experiments where adequate data are available (3 in Qld and 3 in Vic) Working with the DCCEE NCAS model objective is to test and improve NCAS if required Soil organic carbon (Mg C/ha) Time (y) Soil organic carbon (Mg C/ha) Time (y) Calibration

20. Linkage of SCaRP to NCAS modelling Soil organic carbon (g C/kg soil) Frequency distribution T1T1 µ1µ1 σ1σ1 T2T2 µ2µ2 σ2σ2 Use the frequency distribution to initialise NCAS Define a modelling scenario and sample the frequency distribution  SOC Cumulative Frequency Management practice 1 Management practice 2

21. Impact of introducing perennial pasture species on soil carbon 0 5 10 15 20 25 WA Kikuyu SA Kikuyu WA Panic-Rhodes % of SOC derived from new perennial grasses 0 10 20 30 40 50 60 70 WA Kikuyu SA Kikuyu WA Panic-Rhodes annual perennial n = 4 or 5 0-30 cm SOC (Mg C/ha) Providing a C 14 -CO 2 atmosphere Allow plants to capture C 14 Define below ground allocation and stability

22. Why are we taking a regional approach? – the climate factor

23. Why are we taking a regional approach? – the soil type factor 010101230246 Calcarosol Chromosol Ferrosol Vertosol 0 50 100 150 200 Soil Depth (cm) Soil organic carbon content (% by weight) 2 Carbon is typically concentrated near the surface 0-30 cm soil layer Different soils contain different amounts of carbon

24. Why are we taking a regional approach? – the previous management factor 0 10 20 30 40 50 60 70 198220001917200019802000 Brigalow, Qld (cropping) Horsham, Vic (wheat – fallow) Brookton, WA (ceral - lupin - pasture) Total organic carbon (Mg C/ha) Skjemstad and Spouncer. 2003. NCAS Technical Report No. 36.

25. Summary SCaRP is using consistent sampling and analytical protocols. Data collected on past management practice is critical. SCaRP has the potential to deliver into a range of carbon offsetting approaches. However the focus is on the measurement/modelling version. SCaRP was not designed to deal with all aspects of offset methodology (e.g. additionality, leakage, etc) and it was not intended to be comprehensive. SCaRP will provide (region by soil type) assessments of the implications of management practice on soil carbon status. Strong links between SCaRP and DCCEE carbon accounting exist. Science should be viewed as a facilitator for carbon offsets development through provision of data and confidence..

26. Thank you Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: Enquiries@csiro.au Web: www.csiro.au Jeff Baldock Research Scientist CSIRO Land and Water Phone: +61 8 8303 8537 Email: Jeff.Baldock@csiro.au Australian Government Department of Agriculture, Fisheries and Forestry

28. Additional analyses: multivariate analyses Soil organic carbon (g C/kg soil) Frequency distribution T1T1 µ1µ1 σ1σ1 T2T2 µ2µ2 σ2σ2 Multiple gradients Multivariate analyses Multiple regression SOC = a + b(clay) + c(rain) +... R 2 and p-value to evaluate Principal Components Regression Partial Least Squares Principal components Loadings Rain %Pas Clay Sand Scores

29. Size of residual Frequency distribution T2T2 µ2µ2 σ2σ2 T1T1 µ1µ1 σ1σ1 Statistical analyses: removing variability associated with factors other than management Soil organic carbon (tC/ha) Frequency distribution T1T1 µ1µ1 σ1σ1 T2T2 µ2µ2 σ2σ2 Size of residual Frequency distribution T1T1 µ1µ1 σ1σ1 T2T2 µ2µ2 σ2σ2 Rainfall gradient Remove variability associated with other factors (rainfall)

30. Impact of Australian agriculture on soil carbon: relative and absolute rates of change Min 25 th percentile Median Max 75 th percentile All data normalised to the 0-15 cm soil layer Sanderman et al. 2010. Soil Carbon Sequestration Potential: A review for Australian agriculture. CSIRO Technical report Absolute rates of soil C change were found to be less than relative values 1) Cropping systems - -0.1 to -0.3 Mg C ha -1 yr -1 2) Conversion from crop to pasture - +0.3 Mg C ha -1 yr -1 Relative change in SOC (Mg C/ha/y) -0.500.51.51.0

31. Relative impacts of agricultural practice on soil carbon: International evidence Altered fertiliser inputs Manure inputs Cultivated to grassland Forages in rotations Conservation tillage No-till adoption Hutchinson et. al. (2007) Agric. For. Meteorol. 142: 288-302 Improved grassland management Reduced fallow 0.00.40.60.81.01.20.2 Change in soil carbon (Mg C ha -1 yr -1 )

32. Why are we taking a regional approach? – the previous management factor 0-30 cm soil organic carbon (Mg C ha -1 ) Duration of agricultural production (yr) 0 20 40 60 80 100 020406080100 30 Mg C/ha Intensive agricultural practice 50 Mg C/ha “Carbon friendly” Agricultural practice  C<0  C>0

33. Summary of soil carbon sequestration potential Identify areas (soils) where carbon capture per unit of available resource is not maximised Define whether or not resource use efficiency can be enhanced by management (consider local climate and soil specificity) Maintain current production system Maximise resource use efficiency (e.g. carbon capture per mm water or per kg nutrient) Maximise carbon retention and return to the soil Examples – liming, fertilisation, rotational grazing Shift to alternative production systems Introduction of perennial vegetation where appropriate Alternative crops - lower harvest index Alternative pasture species – increased below ground allocation Green manures

34. Comparison against business as usual – reason for modelling 0-30 cm soil organic carbon (Mg C ha -1 ) Duration of agricultural production (yr) 0 20 40 60 80 100 020406080100 34 Mg C/ha Intensive agricultural practice 14 Mg C/ha “Carbon friendly” Agricultural practice

35. Why increase the amount of carbon captured in soils? - biochemical energy - reservoir of nutrients - increased resilience Biological roles - structural stability - water retention - thermal properties Physical roles Chemical roles - cation exchange - pH buffering - complexes cations The soil productivity perspective Relative importance of the different roles will vary between soils Retention of plant available water: decreases with increasing clay Cation exchange: decreases with increasing clay content Provision of biochemical energy and nutrients: important to all soils

36. Why increase the amount of carbon stored in soils? Potential to sequester C in soil SOC pool size: 1500 Pg Rapid cycling SOC: 500-750 Pg 1% increase in stored SOC/yr: 5 - 7.5 Pg/yr CO 2 -C emissions: 8 Pg/yr Issues Native unmanaged soils Variations in soil properties Permanency of increase Constraints to increasing C inputs to soil (biophysical, economic, social) The carbon sequestration perspective

37. What is required for Australian soils to mitigate net GHG emissions? Australia’s net flux of GHG = 0.15 Pg C y -1 (NGGI, 2009) Australia’s soils are estimated to contain 18.8 Pg C in the 0-30 cm layer (Grace et al. 2006) An annual increase in the storage of carbon of 0.8% across all of Australia’s 769 Mha of soil would mitigate emissions Actively managed agricultural lands account for 6% of land area (~50M ha) Agricultural lands All lands

38. What is required for Australian soils to mitigate net GHG emissions? Soil C change can occur across all agricultural lands including rangelands Scenario 1 Soil C change can only occur on actively managed agricultural lands Scenario 2 Area available (Mha) 46949.6 Annual increase in soil C to offset emissions (Mg C/ha) 0.323.02 50% of the carbon captured by plants and returned to the soil is lost as CO 2 Additional C capture and return to the soil required to offset emissions – without harvest (Mg C/ha) 6.04 0.64

39. Requirements to increase soil carbon: the carbon perspective 0 10 20 30 40 50 60 70 80 90 0.911.11.21.31.41.51.61.7 Bulk density (g/cm3) Amount of carbon in the 0-10 cm layer (Mg C/ ha) 1% SOC 2% SOC 3% SOC 4% SOC 12 24 Amount of C required: 12 Mg C/ha 25 Mg Dry matter (DM)/ha Rate per year 5 Mg DM/ha/y (no losss) 10 Mg DM/ha/y (50% loss) 50% allocation below ground 5 Mg shoot DM/ha/y Additional C capture required by photosynthesis Changing soil carbon from 1% to 2% over 5 years 4.8 Mg C/ha/y

40. Requirements to increase soil carbon: the nitrogen perspective Cleveland and Liptzin (2007) Biogeochemistry, 85:235 (unfertilised, untilled, no intensive agriculture, field fresh) Molar C/N =14.3 ± 0.5 (n=146 soils) Mass C/N = 12.3 ± 0.4 29 soils from southern Australia with total organic carbon contents ranging from 0.8% to 5.7% 0 20 40 60 80 100 120 Surface Residues Buried Residues Particulate OC Humus C/N ratio (mass basis) MinMax SPR19105 BPR1460 POC 1320 Humus 610 Maximum values Minimum values Baldock et al (unpublished)

41. Requirements to increase soil carbon: the nitrogen perspective Changing soil carbon from 1% to 2% SOC requires 1200 kg of N Annual requirement over a 5 year period = 240 kg N/ha/y @ a C/N ratio of 10 Even if C/N = 20, the annual requirement to build SOC would be 120 kg N/ha/y C/N=10 0 1000 2000 3000 4000 5000 6000 7000 1.01.21.41.6 Bulk density (g/cm 3 ) Amount of N (kg/ha) 1.0% SOC2.0% SOC 3.0% SOC4.0% SOC 1200 2400

42. Net primary productivity (NPP) – NLWRA NPP (Mg C ha -1 y -1 ) 0 - 1 1 - 2 3 - 4 4 - 5 5 - 6 6 - 7 7 - 8 8 - 10 10 - 12 2 - 3 Analysis 1 (spatial extent) All soils – 0.64 Mg C/ha Actively managed – 6.02 Mg C/ha Analysis 2 (change in %C of 1% in 5 years) Rate of C capture - 4.8 Mg C/ha/y

43. Issues to consider: saturation and permanence From Petersen et al 2005 1860 1900 1940 1980 100 80 60 40 20 0 Control (no additions) Manure addition then stopped Manure addition maintained Soil organic carbon (Mg C/ha) Management changes that build soil C must be maintained to maintain soil C Soil C storage capacity is finite and the largest changes happen early Soil C changes take place over long time periods Petersen et al. (2005) Soil Biol Biochem 37: 359

44. Relative versus absolute changes in soil carbon Best practice -1.9 0.1 1.0 040 Soil organic carbon (Mg C ha -1 ) Years of cultivation Conventional -2.9 -0.9 0.0 Absolute differences Comparison against a previously measured value Single point in time comparison between treatments Soil organic carbon (Mg C/ha) Treat 2 Treat 1 50 75 25 Relative differences

45. National Carbon Accounting System: an overview Spatial datasets Climate, Soil properties, veg cover, etc Remote sensing 15 Landsat images from 1972 - 2006 Site specific management and production data Soil carbon cycling model calibrated to measureable fractions of SOC

46. Conclusions: Capturing carbon in Australian Soils Enhancing SOC has benefits beyond the context of C accounting Australian soils do have a place in emission mitigation, but are unlikely to provide the long term solution Capacity is finite and largest changes occur early Relative increases <0.5 Mg C/ha/y Absolute increases - negative for cropping systems and <0.5 Mg C/ha/y for conversion to grasslands Opportunities for additional carbon capture in soils exist where: Inefficiencies in current production systems can be removed or reduced Alternative systems with higher carbon capture per increment of resource use are available There will not be one solution – solutions need to be adapted to specific soil and climate conditions

47. Conclusions: Capturing carbon in Australian Soils Constraints Farmers are paid to remove carbon in products Future liabilities and implications on land values Uncertainty in value of carbon and agricultural products Measurement – spatial variability and degree of confidence A new national project will define the impact of several agricultural management practices at a regional scale and provide data for further NCAS development Australia has taken a Tier 3 approach to soil carbon accounting based on calibration of measurable fractions of soil carbon

48. Inputs of carbon from perennial pastures: 14 C labelling studies 14 C-CO 2 14 C Time

49. Inputs of carbon from perennial pastures: C 3 /C 4 pasture transitions Temperate plants (C 3 ) capture carbon during photosynthesis using a different process than tropical grasses (C 4 ) This provides a basis to differentiate carbon derived from C 3 vegetation from carbon derived from C 4 vegetation  13 C C 3 plants (-27) C 4 plants (-11) 0 -10 -20 -30 -40 Frequency

50. Inputs of carbon from perennial pastures: C 3 /C 4 pasture transitions t0t0 t Soil C old C 3 new C 4 C 3 -  13 C C 4 -  13 C  13 C C 3 veg = -27  13 C C 4 veg = -11  13 C C 3 ref soil = -27  13 C C 3 C 4 soil = -18 Initial results SW WA – kikuyu has added approximately 8 t C ha -1 y -1 (10 years) NW WA – panic/rhoades grass has not altered soil carbon (7 years)