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

Transcription

1 Soil carbon Productivity benefits, methods explained, applicability in South West Queensland and implications Diane Allen, DSITI: Carbon workshop Charleville 15/12/2015

2 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?

3 Source:

4 Raymond (2005) Nature 436,

5 Kaiser et al. 2015, Nature comms Raymond (2005) Nature 436, As some of the soil microbial community produce enzymes to break down organic matter, C and N is lost in the process

6 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

7 SOC: a function of the inputs and outputs Plants & animals Soil surface Decomposable organic residues CO 2 Soil biomass CO 2 CO 2 Courtesy Ram Dalal, DSITI Humus

8 Total Carbon Humus, particulate, resistant carbon pools Total carbon or a sum of its parts Living organisms and roots (labile) < 5% Fresh residues (labile) < 10% Soil health Particulate organic C (labile) 10 50% Nutrient cycling Humus (decadal) 33 50% Char or black carbon/resistant Carbon sequestration (inert) 1 30% Adapted from Skjemstad & Baldock, 2000

9 What are the productivity benefits of managing SOC? Sources: Text (United Nations Environment Program); Photos (Soil Science Society Australia)

10 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

11 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

12 Australia has 14 soil types (Soil Orders), reflecting the arid, stronglyweathered nature of the Australian continent Charleville western Qld: Cracking clay soils Vertosols Massive earths Kandosols Texture contrast soils Sodosols Deep sandy soils - Tenosols

13 Kandosols Vertosols Sodosols Tenosols

14 Soil Depth (cm) 0 Soil organic carbon content (% by weight) Soil 1 Soil 2 Soil 3 Soil 4

15 What affects soil organic carbon levels? Climate: Temperature, rainfall, Vapour Pressure Deficit Vegetation type Soil texture and type of clay and oxides (Parent Material) Topography Time The 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

16 Viscarra Rossel et al. 2014, Global Change Biology

17 SOC % Equilibrium level Land use or management change (Pasture/Forestry) New equilibrium level (cropping) Time

18 Cropping and soil carbon, Queensland Dalal and Meyer Aust. J. Soil. R, 1986 Sanderman and Baldock, S.R.Letters, 2010

19 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

20 Soil (and carbon) loss - erosion Land slip Wind Rill and sheet Tunnel Gully Scald Stream Bank

21 Australian Government workstream: Soil Carbon Soil Carbon Research Program (SCaRP) (Program leader Jeff Baldock, CSIRO) National Soil Carbon Program (NSCP) (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 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, Linkage with DAFF Action on the Ground program which trial and demonstrate a range of on-farm technologies and practices

22 Measurement approach: Australia example Source: Commonwealth of Australia, 2015

23 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?

24 Sampling design and approach: Australia example Sanderman et al Orton et al. 2015

25 Sampling design and approach: Australia example

26 Total Carbon Humus, particulate, resistant carbon pools Total carbon or a sum of its parts Living organisms and roots (labile) < 5% Fresh residues (labile) < 10% Soil health Particulate organic C (labile) 10 50% Nutrient cycling Humus (decadal) 33 50% Char or black carbon/resistant Carbon sequestration (inert) 1 30% Adapted from Skjemstad & Baldock, 2000

27 Total SOC and C fractions sieving & combustion Total SOC: sample usually air-dried and sieved to 2mm particle size POC 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

28 Prediction using infra-red spectroscopy Relies on statistical relationships between infra-red (IR) soil spectra and results from soil C measurements Baldock et al 2013 Soil Research

29 Grazing lands management, northern Australia and SOC Latitude 25 S 20 S 15 S 10 S DARWIN Kidman Springs Toorak 2 BRISBANE 130 E 135 E 140 E 145 E 150 E Longitude Wambiana * 15* 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

30 Pasture grazing - Sheep Latitude 25 S 20 S 15 S 10 S DARWIN Kidman Springs Wambiana 14 Toorak * 13 15* 11 2 BRISBANE 130 E 135 E 140 E 145 E 150 E Longitude 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). Pringle el et al. 2013, Geoderma

31 Latitude 25 S 20 S 15 S 10 S DARWIN Kidman Springs Wambiana 14 Toorak * 13 15* 11 2 BRISBANE 130 E 135 E 140 E 145 E 150 E Longitude Grazing: stocking intensity Beef cattle Trial commenced in 1997 comparing different types of cattle grazing intensity (no grazing, light moderate, heavy) 10 sites ~ 1,000,000m 2 each Soil C stocks showed a strong interaction between grazing pressure x soil type Allen et al 2009; Pringle el et al. 2011

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33 Understanding carbon changes using carbon models Full Carbon Accounting Model (FullCAM) Soil sub model

34 Soil organic carbon (g C kg -1 soil) Understanding carbon changes over time using carbon models Initiate land use Land use change TOC HumC POC ROC less humus C Years 18 y 10 y more POC Courtesy Jeff Baldock, CSIRO

35 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 semiarid rangelands of western NSW The fate of aboveground carbon inputs: a key process that is poorly understood

36 Soil Methods Under ERF agriculture and vegetation sectors^ Agriculture Vegetation management 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 * 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 *methods transitioned from CFI to ERF on 01/07/2015 ^as at 01/12/2015

37 Source: Commonwealth of Australia, 2015 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

38 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

39 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

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41 More info? Qld Globe: farming, planning, soils, vegetation, inland waters

42 Soils globe soil surveys and reports

43 Site observation Soil morphology described Lab test results e.g. ph, electrical conductivity Chloride, organic Carbon, Total N, K, P

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45 international-year-of-soil-2015-activities