Soil Organic Carbon (SOC)

AUS-AKW-AGR-SOC General Moderate confidence

Benchmark Value

No specific value — see range

Range: 1.51 to 1.7 %

Thresholds: Lower: 0.8, Upper: —

Optimal Range: 1.51 to 1.7

Direction: Higher is desirable ↑

Form: OptimalRange

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

The 75th percentile SOC benchmark for Clay Loam soil texture is 1.51 - 1.85%.

Metric Definition:

Soil Organic Carbon (SOC) concentration in the top 0-10 cm soil layer under agricultural cropping on calcareous soils (Calcarosols).

Benchmark Definition:

The reference value represents the 75th percentile of observed SOC in the 0-10 cm layer of cropping systems on calcareous soils (Calcarosols) in the Eyre Peninsula, a robust proxy for the specified biome and land use.

Justification:

This context-specific threshold is more relevant than the generic 2% threshold for arid systems where native SOC is often <1%.

Sources (1)

Preview of Soil carbon monitoring and trends - Department for Environment and Water, accessed August 5, 2025,

Soil carbon monitoring and trends - Department for Environment and Water, accessed August 5, 2025, Government

Common soil types | Environment, land and water - Queensland Government

View Source

Supporting Sources (37)

Additional references from the underlying research that informed this benchmark.

(PDF) Drivers of soil organic carbon storage and vertical distribution in Eastern Australia, accessed July 22, 2025,

Contextual Support Government

Soil respirationdriven CO2 pulses dominate Australia's flux variability

View Source

Preview of Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change - PubMed, accessed July 22, 2025,

Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change - PubMed, accessed July 22, 2025,

Contextual Support Journal

Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change - PubMed Central, accessed July 22, 2025,

View Source

Calcareous Soils Initiative - GRDC, accessed July 22, 2025,

Contextual Support Government

Calcareous Soils Initiative - GRDC, accessed July 24, 2025

View Source

Climate of South Australia - Britannica, accessed July 22, 2025,

Contextual Support GreyLiterature

Mediterranean forests, woodlands and scrubs – Australian Acoustic Observatory | A2O, accessed July 13, 2025

View Source

Discover the Top 6 Benefits of Regenerative Farming in Australia, accessed July 22, 2025,

Contextual Support Government

Regenerative ... - Landscape South Australia - Eyre Peninsula, accessed August 28, 2025,

View Source

Exploring Soil Carbon in the Mallee - Soils Connect, accessed July 6, 2025,

Direct Evidence GreyLiterature

Mallee plants - Australian National Botanic Gardens, accessed July 22, 2025,

View Source

Eyre Peninsula | South Australia | soilquality.org.au, accessed July 22, 2025,

Contextual Support Government

Eyre Peninsula | South Australia | soilquality.org.au, accessed July 27, 2025,

View Source

Farmers take up soil carbon improvements - Landscape SA, accessed July 22, 2025,

Contextual Support Government

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed July 22, 2025,

View Source

Forest Soil Heterogeneity and Soil Sampling Protocols ... - SciSpace, accessed July 22, 2025,

Direct Evidence Journal

Australian Soil Classification edition 3 - CALCAROSOLS, accessed July 22, 2025,

View Source

Full article: Making soil carbon credits work for climate change mitigation, accessed July 22, 2025,

Contextual Support Journal

Full article: Making soil carbon credits work for climate change mitigation, accessed July 22, 2025,

View Source

functions-of-soil-organic-matter-and-the-effect-on-soil-properties.pdf.pdf, accessed July 22, 2025,

Contextual Support Journal

The Rangeland Journal - CSIRO PUBLISHING

View Source

Preview of How much organic carbon could the soil store? The carbon sequestration potential of Australian soil - Rothamsted Repository, accessed July 22, 2025,

How much organic carbon could the soil store? The carbon sequestration potential of Australian soil - Rothamsted Repository, accessed July 22, 2025,

Direct Evidence

How much organic carbon could the soil store? The carbon sequestration potential of Australian soil - Rothamsted Repository, accessed July 22, 2025,

View Source

Joe Jennings map collection | Catalogue | National Library of Australia, accessed July 22, 2025,

Irrelevant

Joe Jennings map collection | Catalogue | National Library of Australia, accessed July 22, 2025,

View Source

Preview of Karstic Landscapes Are Foci of Species Diversity in the World's Third-Largest Vertebrate Genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata; Gekkonidae) - MDPI, accessed July 22, 2025,

Karstic Landscapes Are Foci of Species Diversity in the World's Third-Largest Vertebrate Genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata; Gekkonidae) - MDPI, accessed July 22, 2025,

Contextual Support Journal

Karstic Landscapes Are Foci of Species Diversity in the World's Third-Largest Vertebrate Genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata; Gekkonidae) - MDPI, accessed July 22, 2025,

View Source

Managing nutrient deficiencies in crops on calcareous soils - Cherry Times, accessed July 22, 2025,

Direct Evidence Journal

Managing nutrient deficiencies in crops on calcareous soils - Cherry Times, accessed July 22, 2025,

View Source

$Preview of Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 22, 2025,$

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 22, 2025,

Contextual Support Journal

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 22, 2025,

View Source

$Preview of Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 6, 2025,$

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 6, 2025,

Direct Evidence Journal

Pedogenic controls of soil organic carbon stocks and stability beneath montane Norway spruce forests along a precipitation gradient - PMC, accessed March 28, 2026,

View Source

Preview of Measuring organic carbon in Calcarosols: understanding the pitfalls and complications - CSIRO PUBLISHING | Soil Research, accessed July 22, 2025,

Measuring organic carbon in Calcarosols: understanding the pitfalls and complications - CSIRO PUBLISHING | Soil Research, accessed July 22, 2025,

Methodology Source Journal

Measuring organic carbon in Calcarosols: understanding the pitfalls and complications - CSIRO PUBLISHING | Soil Research, accessed July 22, 2025,

View Source

Measuring organic carbon in Calcarosols: understanding the pitfalls and complications, accessed July 22, 2025,

Direct Evidence Journal

Soil Salinity Explained, accessed July 11, 2025,

View Source

Pasture cropping: A regenerative solution from Down Under | Opinions | Al Jazeera, accessed August 4, 2025

Direct Evidence GreyLiterature

An Economic Analysis of No-till Farming on the Upper Eyre Peninsula SA - CABI Digital Library, accessed July 22, 2025,

View Source

Practice Guide: Multispecies Cropping - Soils For Life, accessed August 4, 2025

Direct Evidence GreyLiterature

Plant-based solutions to improve soil performance - Fact sheet ..., accessed July 7, 2025,

View Source

Practice Guide: Multispecies Cropping - Soils For Life, accessed July 22, 2025,

Contextual Support GreyLiterature

Practice Guide: Multispecies Cropping - Soils For Life, accessed July 22, 2025,

View Source

$Preview of Quantifying organic carbon in particulate and mineral-associated fractions of calcareous soils 20 - WUR eDepot, accessed July 22, 2025,$

Quantifying organic carbon in particulate and mineral-associated fractions of calcareous soils 20 - WUR eDepot, accessed July 22, 2025,

Direct Evidence Journal

Quantifying organic carbon in particulate and mineral-associated fractions of calcareous soils 20 - WUR eDepot, accessed July 22, 2025,

View Source

Regenerative Agriculture - Landscape SA, accessed July 6, 2025,

Direct Evidence Government

Regenerative Agriculture - Local Land Services

View Source

Regenerative agriculture in Australia: the changing face of farming - Frontiers, accessed August 4, 2025

Direct Evidence Journal

NCC: Regenerative Agriculture and Soil Health - Wet Tropics Plan, accessed July 27, 2025,

View Source

Preview of Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed August 5, 2025,

Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed August 5, 2025,

Direct Evidence Journal

Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed August 28, 2025,

View Source

Revitalize Dry Land with Regenerative Agriculture Practices, accessed July 6, 2025,

Direct Evidence GreyLiterature

Pasture cropping: A regenerative solution from Down Under | Opinions | Al Jazeera, accessed July 22, 2025,

View Source

Soil 6 the driver of carbon dioxide variability over Australia, accessed July 22, 2025,

Contextual Support Journal

Soil 6 the driver of carbon dioxide variability over Australia, accessed July 22, 2025,

View Source

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed August 5, 2025,

Direct Evidence Journal

Spatial distribution of soil microbial activity and soil properties ..., accessed August 13, 2025,

View Source

Soil Constraints in an Arid Environment—Challenges, Prospects, and Implications - MDPI, accessed July 6, 2025,

Direct Evidence Journal

Soil pH | Environment, land and water - Queensland Government, accessed July 28, 2025

View Source

Soil management - Landscape South Australia - Eyre Peninsula, accessed July 13, 2025

Direct Evidence Government

Soil management - Landscape South Australia - Eyre Peninsula, accessed July 23, 2025

View Source

Soil organic matter in cropping systems - NSW Department of Primary Industries, accessed July 22, 2025,

Direct Evidence Journal

III. WORKING PAPERS - Food and Agriculture Organization of the United Nations, accessed July 26, 2025,

View Source

soil_carbon_guidelines.docx - Department for Environment and Water, accessed July 22, 2025,

Direct Evidence

soil_carbon_guidelines.docx - Department for Environment and Water, accessed July 22, 2025,

View Source

Preview of Some Characteristics of Calcareous soils. A review A.S. Taalab1, G.W. Ageeb2, Hanan S. Siam1 and Safaa A. Mahmoud1 - CURRENT RESEARCH WEB, accessed July 22, 2025,

Some Characteristics of Calcareous soils. A review A.S. Taalab1, G.W. Ageeb2, Hanan S. Siam1 and Safaa A. Mahmoud1 - CURRENT RESEARCH WEB, accessed July 22, 2025,

Methodology Source Journal

Some Characteristics of Calcareous soils. A review A.S. Taalab1, G.W. Ageeb2, Hanan S. Siam1 and Safaa A. Mahmoud1 - CURRENT RESEARCH WEB, accessed July 22, 2025,

View Source

Preview of Time of sowing influences wheat responses to applied phosphorus in alkaline calcareous soils in a temperate climate - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 22, 2025,

Time of sowing influences wheat responses to applied phosphorus in alkaline calcareous soils in a temperate climate - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 22, 2025,

Contextual Support Journal

Overcoming soil constraints in highly calcareous soils - Soil CRC, accessed July 22, 2025,

View Source

Understanding the Impacts of Soil, Climate, and Farming ... - Frontiers, accessed July 6, 2025,

Direct Evidence Journal

Modeling Soil Organic Carbon Change across Australian Wheat Growing Areas, 1960 62010, accessed July 22, 2025,

View Source

Understanding your soil carbon project - simple method guide - Clean Energy Regulator, accessed July 22, 2025,

Contextual Support GreyLiterature

Understanding your soil carbon project - simple method guide - Clean Energy Regulator, accessed July 22, 2025,

View Source

Context

Region Australia
Biome Arid Karstic Woodlands & Shrublands
Land Use Agricultural Crop Production
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 19 Mar 2026

Notes

Lower Critical Threshold: 0.8 %. No upper detrimental threshold — higher values are always better up to natural saturation. Represents the 50th to 75th percentile of observed SOC in well-managed proxy systems. This range is associated with the functional benefits of regenerative agriculture, including improved soil structure, water use efficiency, and resilience to drought. There is no evidence of a detrimental ecological threshold where high SOC becomes harmful. The upper limit is a natural saturation point ("attainable maximum") determined by soil texture (clay+silt content) and climate (biomass inputs), not negative feedback. Agronomic issues like temporary nitrogen drawdown are management challenges related to the C:N ratio of inputs, not a flaw of high carbon stocks. RangeFixup applied 2026-03-21 22:21 UTC: LowerBound: 1.51 → 1.1; OptimalRangeLow: 1.1 → 1.51 [Migration] Original wider evidence range: 1.1 – 1.85 (retained OptimalRange: 1.51 – 1.7)

Related Benchmarks

Other benchmarks in the AUS-AKW-AGR-SOC family.