Soil Organic Carbon (SOC)

AUS-TMI-AGR-SOC General Moderate confidence

Benchmark Value

No specific value — see range

Range: 1.9 to 2.2 %

Thresholds: Lower: 1, Upper: —

Optimal Range: 1.9 to 2.2

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. The scoring engine uses 3 benchmarks together — the OptimalRange form drives the primary score, while 2 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard Point Guard

Evidence & Context

Functional Range Summary: Lower Critical Threshold: Evidence from tropical agroecosystems suggests a critical threshold of 1.0–1.2% SOC. Below this range, soil function, nutrient cycling, and crop response to inputs are significantly compromised. Optimal Range: Research on tropical Ferralsols identifies an optimal range of 1.9–2.2% SOC for achieving high agronomic efficiency and crop yields, representing a state of high soil health and productivity.

Metric Definition:

Soil Organic Carbon (SOC) concentration in the top 0–10 cm of soil.

Benchmark Definition:

Soil Organic Carbon concentration in tropical maritime island agricultural soils representing soil health and productivity, with a lower critical threshold below which soil function is compromised and an optimal range associated with high agronomic efficiency.

Justification:

The benchmark is derived from analogous, well-studied, high-functioning agricultural systems in mainland tropical Australia, which share comparable climatic, pedological, and management characteristics.

Sources (3)

Preview of (PDF) Soil Organic Carbon – Role in Rainfed Farming Systems With ...

(PDF) Soil Organic Carbon – Role in Rainfed Farming Systems With ... GreyLiterature

Soil Organic Carbon – Role in Rainfed Farming Systems With Particular Reference to Australian Conditions - ResearchGate

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Soil | Australia state of the environment 2021

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Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - ResearchGate, accessed July 25, 2025, Journal

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - ResearchGate

Supporting Sources (37)

Additional references from the underlying research that informed this benchmark.

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a comparisonof the soils of tropical latin america ano tropical australia

Contextual Support Journal

A comparison of the soil of tropical latin america and tropical australia

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Australia's bioregions (IBRA) - DCCEEW, accessed July 15, 2025

Contextual Support

Interim Biogeographic Regionalisation for Australia (IBRA), Version 7 (Regions)

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Can best agricultural practices saturate the organic carbon in tropical soils? - ResearchGate

Contextual Support GreyLiterature

Can best agricultural practices saturate the organic carbon in tropical soils? - ResearchGate, accessed July 19, 2025

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Carbon farming | CottonInfo

Contextual Support GreyLiterature

Carbon farming | CottonInfo

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Characteristics and Drivers of Soil Organic Carbon Saturation Deficit in Karst Forests of China - MDPI

Contextual Support Journal

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG

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Climate of Australia - Wikipedia, accessed July 13, 2025

Contextual Support GreyLiterature

Climate of Australia - Wikipedia

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Common soil types | Environment, land and water - Queensland Government, accessed August 9, 2025

Contextual Support Government

Sodic & Alkaline Soil - Soil Quality Knowledge Base

Preview of Common soil types | Environment, land and water | Queensland ...

Common soil types | Environment, land and water | Queensland ...

Contextual Support Government

Phosphorus nutrition of phosphorus-sensitive Australian native ...

Preview of critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

Contextual Support GreyLiterature

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

Preview of critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate, accessed August 3, 2025,

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate, accessed August 3, 2025,

Contextual Support

National Soil Strategy

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Ecological Regions Of Australia - WorldAtlas, accessed July 27, 2025,

Contextual Support GreyLiterature

Ecological Regions Of Australia - WorldAtlas, accessed August 4, 2025,

Preview of Enhancing Organic Carbon Content in Tropical Soils: Strategies for Sustainable Agriculture and Climate Change Mitigation - ResearchGate

Enhancing Organic Carbon Content in Tropical Soils: Strategies for Sustainable Agriculture and Climate Change Mitigation - ResearchGate

Contextual Support Journal

AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT - Norfolk Island Regional Council

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Growing soil organic carbon in dryland agricultural systems - CSIRO Publishing, accessed July 6, 2025,

Contextual Support Journal

Regenerative agriculture in Australia: the changing face of farming - Frontiers, accessed July 8, 2025

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HOW TO MEASURE AND INTERPRET RESULTS IN RELATION TO SOIL ORGANIC CARBON - Grains Research and Development Corporation (GRDC), accessed August 5, 2025,

Methodology Source Journal

(PDF) Soil organic carbon stocks in saline and sodic landscapes

Preview of Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

Contextual Support Journal

Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

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Lord Howe Island Palms

Contextual Support GreyLiterature

Lord Howe Island supports a once-contiguous population of palm trees. Two soil types emerged on the - Chegg

Preview of Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

Contextual Support Journal

Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

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

Contextual Support Journal

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Contextual Support Journal

soils - of the australian alps

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Norfolk Island Plant Communities - Jerry Coleby-Williams

Contextual Support Journal

Norfolk Island Plant Communities - Jerry Coleby-Williams

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Regenerative agriculture in Australia: the changing face of farming - Frontiers

Contextual Support GreyLiterature

Regenerative agriculture in Australia: the changing face of farming - Frontiers

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

Contextual Support Journal

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Responses to controlled release potassium fertilisers in agriculture following phosphate mining - CSIRO PUBLISHING | Soil Research, accessed July 30, 2025,

Contextual Support Journal

Cocos nucifera L. - Forest Service, accessed July 30, 2025

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Soil carbon | Environment, land and water - Queensland Government

Direct Evidence Journal

Soil carbon | Environment, land and water - Queensland Government

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Soil carbon saturation: Linking concept and measurable carbon pools

Contextual Support Journal

Soil carbon saturation: Linking concept and measurable carbon pools, accessed July 19, 2025

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Soil Carbon Saturation: What Do We Really Know? - PMC - PubMed Central

Contextual Support Journal

Soil Carbon Saturation: What Do We Really Know? - PMC - PubMed Central

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

Contextual Support GreyLiterature

Coexistence of shrubs and grass in a semi-arid landscape: a case study of mulga (Acacia aneura, Mimosaceae) shrublands embedded in fire-prone spinifex (Triodia pungens, Poaceae) hummock grasslands - CSIRO PUBLISHING | Australian Journal of Botany

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Soil Carbon Snapshot - Agriculture Victoria, accessed August 5, 2025,

Contextual Support Journal

Soil Carbon Snapshot - Agriculture Victoria

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Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland - ResearchGate

Direct Evidence Journal

Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland

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Soil organic carbon is at risk in a large part of European agricultural land - EU Science Hub

Contextual Support Government

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Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - JRC Publications Repository, accessed August 3, 2025,

Direct Evidence GreyLiterature

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - JRC Publications Repository, accessed August 3, 2025

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Soil organic matter in dryland systems – management and opportunities - GRDC

Contextual Support Government

Soil Respiration and Carbon Balance Under Cover Crop in a no-Till Tropical Fruit Orchard - Frontiers

Preview of The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets

The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets

Contextual Support Government

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The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets, accessed July 25, 2025,

Contextual Support GreyLiterature

Geology - Norfolk Island Flora & Fauna Society

Preview of Too Much Organic Matter - Maine Organic Farmers and Gardeners Association

Too Much Organic Matter - Maine Organic Farmers and Gardeners Association

Contextual Support GreyLiterature

Too Much Organic Matter - Maine Organic Farmers and Gardeners Association

Preview of Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Contextual Support GreyLiterature

Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Agricultural Crop Production
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 4 Jun 2026

Notes

Lower Critical Threshold: 1 %; No upper detrimental threshold — higher values are always better up to natural saturation. The lower critical threshold range of 1.0–1.2% SOC indicates compromised soil function and productivity below this level. The optimal range of 1.9–2.2% SOC is associated with high agronomic efficiency and crop yields.

Related Benchmarks

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